Page 2
Minima of Variable Stars of the Algol Type (continued).
R-CANIS MAJ. 39+ 8 LIBRÆ 88 *.
U CORONA 89 * (continued). (2d 7h 51m)
(continued). Sept. Nov.
Jan. June.
March, July. dhm d hm dh m dhm
dhm
d hm I 12 I 2013 I 14 30 4 5
5 II 25 7 18 4 4 21 49 5 6 o 6 6 12
I2 9 8
14 15 46 8 7 36 8 15 48 10 21 55
19
6 21 13 28 II 17 24 12 I 35 15 13 38 18 4 9
28 II 10 15 15 II 22
20
5 21
22 19 52 18 12 58 18 21 10
3 27 II 35
April. August. 21 22 45 22 6 57
29 12 46 25 8 33 25 16 44
2 14
4 8 53 28 18 20
Feb. July 29
8 23 56 II 6 35 2 3 4 29
3 17
15 21 38
18 4 17 Oct. Dec.
o 7 20 12
22 19 20 25 I 59 II 10 43 12 II 55
29 17 3 31 23 41 2 4 7 2 12 19
16 2 26
17 5 13 55
3 37
May.
21 1920 20 18 8
Sept. 8 23 42 9 7 53
25 9 51 I 2 9 29
3 12 17 41
7 21 23
30 I 34 13 12 27 15 19 17 16 3 28
March.
20 10 9
14 19 5 19 5 4 19 13 15
21 16 48
August. 27 7 51 22 14 51
22 23 3
28 14 30 3 2 46 26 o 38 26 8 50
3 17 17 June. 7 18 28 29 18 37
Dec. I2 10 II
13 O 42
3 5 33 17
IO 17 16 25
3 15 21 17 37
17 8 8
o 58 22
13 13 13
23 22 40 20 10 55 S CANCRI 52.
31 31 15 33 30 20 22
27 8 38 Jan. June. April.
Sept.
U OPHIUCHI 1177. dhm d hm 4 16 45
5 4
i=od 20 gm 4 40 4 22 44
8 28 9 9 22 59
2=1 16 16 14 10 22 14 ото
14 14 41 23 3 56
3=2 12 22 19 6 24 23 7 36
Feb. 23 22 7
April. Feb. Sept. 27 23 19
28 13 50 dh m
dh m I 15 34 7 19 2
I May.
3 30
2 12 42 II 3 II
Dec. 17 6 40
4 12
5 21 12 20 14 49 2 15 I 2 17 48
7 20 31
5 43 7 6 44 7 9 31
II 5 2
12 14 14 March. Oct. II 22 27
12
14 13 32
15 22 44 16 14 10
17 22
3 19 7 15 2 2 27
21 5 52 21 8 39 21 6 34 22 15 46 II 14 5 15 17 33
25 21 35 26 o 22 24 15 4
26
21 25 5 11
5 27 23 35 29 8 47 30 13 20
Nov. U CORONÆ 89 *
March. May. April. 3 16 48
8 (3d 10h 51m.)
3 6 o 58
2 17 17 9
4 26 13
6 16 36
6 18 12 36
Jan. 4
I 48 Feb.
IO 28
7 9 10 19 o 13
dh m d hm Dec.
13 9 38
12 18 50 2 8 6 5 20 37
16 18 8 May.
16 320 2 3 42 9 5 48
12 18 19 20 2 39 19 II 51 7 11 51 II 15 19
16 3 30
23 II 10
21
Page 3
Minima of Variable Stars of the Algol Type (continued). U OPHIUCHI 117 $
Y CYGNI 152
S ANTLIÆ 56 § (continued). (continued).
(continued). June. August. April. August. Feb. June. dh m dhm
d hm dhm
db m 1 21 54
18 I 39 3 II 54
19 7 46
I 21 44
I 20 20 5 6 24
21 10
9 9 II 44 25 7 35 5 3 32 5
8 8 14 55 24 18 40 15 II 33 31 7 24
8 9 20
8
7 56 II 23 26 28 3 II 21 II 22
II 15
8
II 13 44 15 7 56 31 II 41
27 II II
Sept.
14 20 56 18 16 27
14 19 32 18
2 44 18 1 20 2 0 58 Sept.
21 May.
21 8 32
7 8 25 9 28
12 7 3 3 20 12
24 14 20 24 12 56 II O 18
8
27 18 44 7 4 43
24
9 10 50 10 13 13 July.
15 10 39 30
6 13 21 44
30 21 10 28
March. Oct. 17 6 15
27 10 17 5 II O 20 14 45
Oct. 3 I 56 3
o 44 8 19 31
6 6 20
6 7 44 12 4 1 27 7 46 June.
9 13 32
9 12 20 12
6 15 12 32 30 16 17
9
12 18 8 2 IO
12 19 20 6
18 5 58 18 21 3
16 I 8
15 23 56 8 22 5 33 Oct. 9 56 24 5 47
19 6 56 19 5 44 14 9 45 25 14 4
30 5 36 22 12 44
22 II 32 4 o 48 20 9 34
25 18 32
25 17 20 7 919 Nov.
8 O 20
29 IO 17 49 August. 14 2 20
July.
I
7 5 17 10 50
II 5 15 April.
Nov. 4 15 36 20 19 21
9 12 17 5 4 8 7 24 3 52 8
9 23 4 53
I 6 8 II 27 12 22 14 8 51 29 4 42 4 11 56
4 10 44 14 17
8 30 20 53 20 8 40
7 17 44
7 16 32 Dec. 10 23 32
IO 22 20 Y CYGNI 152 I.
14 5 20 14
4 8 5 4 32
8 17 9 56 August. i=id 11h 57m
II 4 21 20 16 56
20 15 44 2=2 23 55
8 18 17 4 10 23 22 44
23 21 32 3=4 II 52
7 8 8 23 3 59 27 4 32
27 3 20 Jan. Feb. 13 7 57
29 348 30 10 20 30 9 8 d hm 3 14 36 20 13 10
May.
Dec. 26 12 59 S ANTLIÆ 56 §.
3 16 8 15 14 15
3 14 56 March. 21 14 4
Jan.
6 21 56
Jan. 27 13 53
3 44 IO
2 32 4 12 48 dh m
13 9 32 13
8 20 Feb. 10 12 38 O 11 44
16 15 20 15 14 8 16 12 27 3 17 32 19 22 32
8
19 19 56 2 13 42 22 12 16
23 20
23 4 20 2 56 23 28 12
5 1ο 5 8
26 10 8
26
7 32 14 13 2 1
13 10 56 29 15 56 29 14 32
29 13 20 Every fourth minimum only. $ Every tenth minimum only, the others may be found by adding the multiples of period in the following table :
Page 4
point, that on a fine night we lose the opportunity of making observations.
Mr. Turner. I oppose the amendment for many reasons. I agree with Mr. Freeman that there is a distinct advantage in attending the Meeting, and I do not think any of us dispute it; but we have to ascertain which of two parties we shall favour. No doubt by adopting Mr. Chambers's motion we shall exclude a certain number of members from attending regularly who now attend, but, at the same time, we admit others who do not attend. The only question is which of these parties we shall favour. Now the form in which the original motion is cast is superior to that of the amendment, as it gives us the opportunity of making the experiment for a year, which I think would be extremely valuable.
The President. We cannot alter a bye-law for a limited time.
The Astronomer Royal. If the original motion is ruled out of order the amendment takes its place, and, therefore, we can speak
The President. The question is, shall these words be erased from the resolution or not?
The Astronomer Royal. If the original resolution is out of order, the amendment is out of place.
Mr. Knobel. The rule is that the Fellows of the Society shall give permission for the amendment to be put.
The Astronomer Royal. Would it not be better to put it?
Mr. Ranyard. I propose that the amendment be not put, because, if it be put and carried, the question will be discussed at an afternoon meeting, and those who cannot attend an afternoon meeting will not be able to come, because our future meetings will be in the afternoon.
Mr. Knobel. If the amendment is carried, we then have a substantive motion before us.
The President. The question is, shall the words “for the period of one year” be struck out of the motion ?
The Astronomer Royal. I do not think you have to vote on that point yet, the question is whether this amendment is to take the place of the substantive motion. The substantive motion is out of order. What we want to have is something in its place to discuss.
Mr. Mitchiner. I beg to submit that the Astronomer Royal is out of order. If the original resolution is out of order, you cannot put an amendment, except to put to the Meeting that the words be left out, but no amendment can be put to the resolution so long as you rule it is out of order.
Mr. Chambers. I beg to withdraw the words you have ruled out of order.
The President. Will the seconder agree to that ?
[Leave was then given to withdraw the words “ for the period of one year.”]
The President. Now we have this resolution without the limit.
Page 5
Mr. Bryant. But it would allow each Member to vote by post.
The President. We tried it, and the result was endless confusion. I think the simplest way will be to put the Astronomer Royal's motion.
Mr. Roberts. I know one gentleman who does not attend these Meetings because he could not get home at night. If you made it 4.30 he could, but if it was made 5 o'clock he could not.
The voting then took place, when the President declared that 19 voted for 5 o'clock, and 17 for 4.30. The resolution was then amended to 5 o'clock.
Mr. Knobel. The Resolution is now :- That henceforth the Meetings of the Society be held at 5 o'clock P.m., and that Bye-law 44 be altered accordingly.”
On a vote being taken, 18 voted for and 30 against, and the Resolution was lost.
Mr. Chambers. Now I beg to demand a poll of the entire body of Fellows, and I would suggest that that should be taken by postcard. [Cries of“No!”] I would point out that it is the universal law of every Company and Society in England, that whenever a motion is rejected or carried on a show of hands, the minority are, by the common law of England, entitled to demand a poll.
The President. Not in this Society; there is nothing in our statutes or bye-laws for such a course. Can you show me a precedent?
Mr. Chambers. The common law of England, 700 years old.
The President. There is no precedent in the Minutes of the Society. Mr. Ranyard. The bye-laws are directly to the contrary. It is
-. said the bye-laws sball not be altered except by vote of General Meeting, or Special Meeting duly called. A canvass by postcard would not be an alteration of bye-laws in the way proposed by the bye-laws of the Society.
Mr. Chambers. Then, if I am debarred the opportunity of learning the wishes of the 500 absent Fellows, I shall take the opportunity of re-opening this question at the Annual Meeting in February next.
The following Candidates were proposed for election as Fellows of the Society :
G. P. B. Hallowes, Surveyor of the Post Office, 77 Lansdowne Road, Didsbury, Manchester (proposed by E. J. Spitta); Shin Hirayama, Astronomer at Tokyo Observatory, Japan (proposed by W. H. M. Christie); R. J. Pearce, M.A., D.C.L., Professor of Mathematics in Durham University (proposed by Rev. T. E. Espin); J. M. Stone, St. John's College, Cambridge (proposed by Dr. A. Wrigley).
Rev. John Mitchell, B.D., 57 Parkgate Road, Chester, was duly elected a Fellow.
Page 6
MEETING OF THE LIVERPOOL ASTRONOMICAL
SOCIETY. The third ordinary Meeting was held on Monday, December 1, at half-past seven o'clock, in the Royal Institution, Colquitt Street.
W. B. Hutchinson, Esq., F.R.A.S., President, in the Chair.
The Rev. Fred. F. Grensted, M.A., gave a lecture on the “ Airless and Waterless Condition of the Moon,” the first part of which was illustrated by numerous views exhibited by means of the lime-light. Equal areas of the Earth's and Moon's surface were shown by means of photographs, of Nasmyth's plaster cast of the lunar surface, and of an albo-relievo map of Asia, and the striking contrast of their configurations dwelt upon.
The Earth's surface being diversified by mountain-ranges and river-systems of drainage, exhibiting clearly marks of denudation and fluviatile erosion, the mountain upheavals having been subject to great lateral pressure. On the Moon's surface, on the other hand, there is nothing that really corresponds to our mountainranges or river-systems, and no evidence of denudation or fluviatile erosion, the most superficial investigation of the lunar surface pointing in the direction of an airless and waterless condition of the Moon throughout its entire history.
The whole problem finds its solution in the difference of size which regulates the rate of cooling, and hence determines chemical differentiation—the greater mass retaining free oxygen, which forms our water and air, the lesser mass using it all up in oxidizing its crust, none being left free, and therefore no water and no air can be formed, assuming the Moon to be composed of similar material and on precisely the same type as the Earth. The Moon being, ronghly speaking, only one fourth of the Earth’s diameter and one eightieth of its bulk, it has therefore a very much greater surface in proportion to its bulk, and would cool with a corresponding degree of quickness. By the pressure of gravitation a pure
metallic nucleus would be formed, possibly of iron, when the heat was still above the point of dissociation—that is, the point admitting of oxidation; hence the nucleus would be pure metal with an outer crust of oxidized metal, which would form as the temperature was reduced and prevent any further oxidation inwards. The Earth having a density of 52 that of water, while its surface rocks only equal about 21, must have a nucleus of 78 times the density of water, and have an oxidized crust one sixth of its radius in depth ; while the Moon having a density of 33 times that of water must be oxidized to nearly a half of its radius from the surface and so have used up all its oxygen, so that none is left free to form water or air.
A vote of thanks having been accorded to the lecturer, an interesting discussion followed.
Several papers were taken as read and will appear in the third number of the Journal.
Page 7
traced past the blue band into the violet, apparently as far as the eye could be expected to follow it.” Although in many parts irregularly encroached upon by absorptive, as well as intensified by emissive effects, it showed, to the most attentive scrutiny, no brightening at the place of the chief nebular ray. Enquiries as to the existence of nebulosity about the stars had similarly a negative upshot. To the practised eyes of Messrs. Burnbam and Barnard, of the Lick Observatory, they seemed quite sharp; and their strong impressions upon a plate exposed by Mr. Roberts for two hours on November ist, 1890, are purely stellar.
Their nearest analogues are found, nevertheless, in planetary nebulæ. The closeness of the affinity has been rendered especially manifest through photographs taken in connection with the Draper Memorial, of fifteen nebular, and all the stellar spectra of this type hitherto discovered. No details of the comparison have yet been published; but it is stated that most of the nebulæ show the stellar blue band, and in the approximate position (1 470) corresponding, it can be inferred, to their simultaneous display of hydrogen-lines. This peculiar quality of radiation, first observed in the annular nebula, Gen. Cat. 4964, by Dr. Huggins in 1864*, was measured, a few years later, as of À 469 with the Harvard College fifteen-inch refractor t, and came out, from Dr. Copeland's determination of it in 1880, in the Stephen-Webb Cygnus planetary, as of 1 469-41. The alternative, more refrangible band at 1 464 has so far not been identified in any nebula. Hence the three stars Lalande 13412, Cygnus Nos. 4001 and 3821 would appear, by the possibly connected circumstances of the low position of the typical blue effulgence, and the emergence in their spectra of hydrogen-lines, to approach planetary nebulæ more closely than the other members of their species. The suggested inference that the order of resemblance traces a line of slow migration, is a plausible conjecture; but it is nothing more. Facts of distribution have to be taken into account. About twentyseven stars of the Wolf-Rayet type are now known $; they all, without exception, occur in the densest parts of the Milky Way. But planetary nebulæ, although strongly preferring, are not limited to the Milky Way. Nor do these share the remarkable clustering tendency of the stars, of which seven are collected in a space of about three degrees square in Cygnus, five are similarly grouped in Scorpio, and two close pairs are met with respectively near y and
Argûs. This associative tendency sets them in a measure apart, and throws them, as it were, off the line of the great highway of development.
A. M. CLERKE.
* Phil. Trans. vol. cliv. p. 440. + Harvard · Annals,' vol. xiii. pt. i. pp. 72, 81. I Copernicus,” vol. i. p. 2.
I take this opportunity of rectifying the erroneous classification of o Muscæ as of the Wolf-Rayet type in the Appendix to my recently-published book . The System of the Stars. All that is yet known of the spectrum of this star is that it includes a bright F, photographically registered at Chosica.
VOL. XIV.
Page 8
ditions which increase or diminish. the chances of cometary discovery, by discussing the connection between the heliocentric longitude of the perihelia of comets and the heliocentric longitude of the Earth at the time that the comets pass through their respective perihelia. This is a problem that he has previously treated in some detail in his paper on the direction of the major axes of cometary orbits; but two causes have contributed to destroy the accuracy of the conclusions to which that discussion led. One is that the solar longitudes were grouped roughly in periods of calendar months, and therefore each group did not contain an equal arc of longitude. The second is that the longitudes of the cometary perihelia were referred to the common equinox of 1850, and therefore the effect of precession in the case of ancient comets had been neglected.
These two sources of uncertainty have induced Dr. Holetschek to abandon the method of grouping, and to draw up a table in which is exhibited for every known comet (omitting some suggested early returns of Halley’s comet) the value of the arc
(1-L+180°), where l and L+180° are respectively the heliocentric longitudes of the comet's perihelion and that of the Earth. The contention is, that since a comet will be at its brightest when its proximity to the Earth occurs simultaneously with its approach to the Sun, and consequently most favourable for detection and observation, thereore a majority of instances this arc (1–L+180°) should be small. The case of comets with small perihelion distances (9) is, however, peculiar, since these comets cannot be seen at perihelion on account of their small elongation, but only as they approach to, or recede from, the Sun; and for those comets in which (9) is less than o'30, the table exhibits the value of (1–L), which, according to the theory here enunciated, ought also to be a small
The choice of the limit, q<0·30, corresponding as it does approximately with the perihelion of Mercury, is, of course, arbitrarily selected, and may operate adversely to the theory is the case of some comets when (9) lies between 0-3 and 0-5, even tending to produce a secondary maximum about 180°.
The study of this table is instructive. It is at once seen that the angular distances between the longitude of the Earth and that of the perihelia are most frequently less than +60°, and that such distances as fall between +120° and +180° occur less frequently than between +60° and +120°, and so far support the theory which Dr. Holetschek advocates. Another feature is the uniformity with which the elliptic comets of short period conform to the rule. Though these comets appear in the table only at the times at which they have been accidentally discovered, yet, on account of their elliptic motion, they can present themselves at one of their many returns in a favourable position for detection, and would therefore unduly tend to swell the number of instances
Page 9
seen from the Earth in January 1891. The satellite nearest the Earth is named first. Apparent distances from the centre of Jupiter are given in multiples of his equatorial radius. E. and W. mark the positions of the Satellites relative to Jupiter.
* shows that the planet is above the horizon of Greenwich ; † that the satellites are moving in the same direction with relatively slow motion; I denotes a very close approach to a conjunction. d hm
dhm I 16 III. II. 94
I. II.
W.** 2 12 47
III. I.
1-25 W. Il 18 43 I. II.
Et 2 16 32 III. IV. 3*2 W. 12 11 14
IV. III.
94 W. 2 17 19 II. IV. 30
W. 12 18 23
I. III.
5'9 W. 3 III. II.
7'0 W.I* 13 16 38 I. III. 5.8 E. 4 14 29
I. II. 4:5 15 9
I. II. 5*77 E.T 5 14 15 I. III. 506 W. 16 14 58
II. III. 205 E. 6 9 9 I. III. 4:5 E.I 17 13 57
III. II.
94 Wt. 8 I. II. 2'25 E.** III, IV. 14:8
W. 8 20 45 III. II.
982 E.
I. II.
1°7
W. 9 18 51 III. II.
91
W.7 As so few of these phenomena are visible within the limits of the British Isles comprising 48only of Longitude from E. to W., I have endeavoured to secure ampler opportunities for observation by sending manuscript copies of this list to the observatories of Madras and Washington, distant 5" 21"
East and 5h 8m West, respectively, by recent mails.
Faithfully yours, Murston Rectory, Sittingbourne,
A. FREEMAN. 1890, Dec. 15.
The early History of the Red Spot on Jupiter. GENTLEMEN
In connection with Mr. Ryle's letter in the December number of the • Observatory,'I trust that I shall not be considered egotistical if I refer your correspondent to a paper by myself, read before the Royal Astronomical Society in 1887. It will be found on p. 515 of Vol. xlvii. of the R. A. S. •Monthly Notices.'
Faithfully yours, Forest Lodge, Maresfield, Uckfield,
WILLIAM NOBLE. 1890, Dec. 5.
Periodical Comets due in 1891. GENTLEMEN,
Our old friend Encke's comet may be confidently expected to turn up again next autumn, as it has been seen at every return since Encke determined its period at the appearance in 1818-19, besides having been observed on three previous occasions, in 1786, 1795, and 1805. We have reason to be grateful to this comet for affording the means of the earliest determination of the mass of the planet Mercury ; but it has other problems yet to solve. Encke's theory respecting the cause of the diminution of the length of its periodic time could not be held (at any rate in its original shape) when it was found that that diminution was not constant in amount. Mr. Monck, I believe, was the first to suggest the retardation produced by traversing or passing near meteoric streams as a cause, and on this we may hope that further light will soon be thrown.
Page 10
The rest of December was warm, and January, with a few exceptions, was also warm.
In 1870-71 the early part of December was cold and the middle portion warm. On December 21 cold set in, lasting, with a few exceptions, until February 2, =44 days: the m.t. of the period was 31o2, or 5°9 below the average; on
10 days the m.d.t. was more than 10° below the average, the g.d. being – 17°•0 on December 25. The rest of February, with one or two exceptions, was warm.
In 1874-75 a cold period set in on December 9, lasting till January 1, =24 days: the m.t. of the period was 31°1, or 7°:9 below the average ; on 6 days the m.d.t. was more than 10° below the average, the g.d. being — 16°4 on December 31. Followed by a very warm January.
In 1878–79, after a somewhat cold period, one of greater cold set in on November 26, lasting till December 25, = 30 days; the m.t. of the period was 32°:1, or 9°•1 below the average; on 12 days the m.d.t. was more than 10° below the average, being for 8 days, December 8 to 15, continuously more than that amount below the average, the g.d. being – 17°•3 on December 24. Then, after 7 days of warm weather, there followed a very cold January.
In 1879-80, after a variable period, cold set in on November 20, lasting till December 27, =38 days: the m.t. of the period was 31°3, or 90.8 below the average ; on 15 days the m.d.t. was more than 10° below the average, being for 8 days, November 30 to December 7, continuously more than that amount below the average, the g.d. being – 19°:2 on December 7. Then, after 8 days warm, followed a very cold January. Great similarity with the previous winter.
A few notes on the winter of 1854-55 (the Crimean winter) may not be out of place. After a variable period, until the middle of January, cold set in on January 14, lasting till February 24, = 42 days: the m.t. of the period was 28°•4, or 9°:4 below the average ; on 18 days the m.d.t. was more than 10° below the average, on 5 of these days being more than 150 below, and on 10 days, February 13 to 22, was continuously more than 10° below, the g.d. being - 1800 on February 18.
As regards absolute low temperature in the months of November and December last, the lowest recorded in November was 18o-3 on the afternoon of November 28 between 4 and 5" P.M., the lowest previously recorded in November since the year 1841 being 1994 on 1856 November 30. The lowest temperature in December was 13°4 on December 22, temperatures lower than which have been recorded only three times in December since 1841: they occurred 1860, December 25=80; 1870, December 25=90-8; and 1878, December 25=12°•2.
W. E.
There is a Greenwich proverb that it is “ never clear when the snow lies ; " and the following figures will show how far the recent severe weather has confirmed this dictum. They give the number of transit observations made during December. The constancy of the watch kept at Greenwich is perhaps too well known to need comment, and it may fairly be said that the following observations were all that were possible during the month.
Page 11
the deduced angular velocity, and in the fourth the mean P.M. ; the ratio of these in the fifth column is seen to be vearly con- stant: No. of
Ang. Mean Stars. A.R. Mec.
vel. P.M. Ratio. Group I.
551 2870:4 +420.0
0":140 o":23 II. 340 279 7 +40 '5 o *295
o 43 III.
+31 '9 o '608
0.85 14 IV.
58 285 2 +30 4 2057
Herr Stumpe remarks that since the mean magnitude of each group is about the same (6:0, 67, 6:1, 6-5), it would appear that the P.M. is a much more satisfactory criterion for the distance of a star than its brightness.
The linear magnitude of the velocity of the Solar system is accordingly left undetermined. We must probably depend on spectroscopic results for this information.
DISTANT COMEts.—The great Lick refractor has to reckon another achievement in opening up the possibilities of following comets for a much longer period than before. Mr. Barnard has been active in this direction, and hopes to follow the Comet 1889 I. for one or two years longer, while another, a faint Comet (1889 b), bas already been followed for a year and a half.
THE REFRANGIBILITY OF THE LIGHT OF Mars. “ Theoretically owing to the deficiency of blue rays in the light of Mars, it should suffer a less refraction than do the stars; and if the difference be sensible it has an important bearing on the solar parallax determinations from Mars.” Accordingly Dr. Elkin has made some experiments on the subject with the Yale heliometer, but he finds that “it is not easy to draw any conclusion as to the relative refrangibility of the light of Mars and a star, beyond that the difference cannot be very large.” (See Astr. Journal,' No. 229).
BRITISH ASTRONOMICAL ASSOCIATION.—We are pleased to see that the B. A. A. is being taken up in the Colonies. The · Cape Times' of Nov. 27 gives a summary of the steps leading up to, and an account of the first meeting. Mr. Cox, of the Observatory at the Cape, seems to be a S. African agent; if astronomers in other colonies will act in the same manner, we shall expect soon to hear of several colonial branches.
Tycho's STAR.--Mr. Burnham has examined the region about the place given by D'Arrest for Tycho's star with the 36-inch. None of the faint stars near the place presented any peculiarity worthy of remark, but three double stars were found.
DOUBLE STARS.—The Transactions of the Royal Irish Academy,' vol. xxix. part 13, contains a collection of double-star measures The great
made by Dr. Doberck during the period 1875-86. There are in all 7969 measures of position-angle and 2656 distances of 366 different couples. Most of these have already been published at different times, so that the value of the present Catalogue lies more in the coinpact form in which it is issued. majority of the measures were made with the Cauchoix equatorial at Markree, which has an aperture of 13'2 inches. The later measures were made at Hong Kong with the Lee equatorial. The tables in connection with the evaluation of the micrometerscrew are not very explicit, and form a great contrast with the catalogue itself, which is everything one could wish. The epoch of 2114 (p. 415) ought to be 77.44.
AMERICAN OBSERVATORIES.—Mr. W. C. Winlock has written an interesting article on Observatories in the U. S. for an Encyclopædia, from which we glean that there are about 60 observatories, exclusive of those of amateurs possessing telescopes of 4 inches or less aperture. A list of observatories with their instruments, and special remarks, is given, and a brief history of Harvard and Lick.
The University of North Carolina appears to have been the astronomical pioneer of the States, for in 1824, Dr. Caldwell, the President, purchased in London the following instruments :transit and a zenith telescope (Simms), equatorial (Dollond), sextant (Wilkinson), reflecting circle (Harris), quadrant (Hadley), and clock (Molyneux). They were erected in the University Building and 7 years later the first observatory was built for their reception, and Caldwell, Elisha Mitchell, and James Phillips observed with them. In 1838 the building was partially destroyed by a fire, which seems also to have enveloped the records and the zeal of the observers, as it closed the astronomical history of the institution. The Hopkins Observatory of Williams College, which celebrated its jubilee a few years back, came next, having been established in 1836, and others followed at sbort intervals, until 1843, when Harvard was founded. It is worthy of note that in 1815 there was some idea of establishing an Observatory at Cambridge, but no action was taken until 1827, when the Dana house was purchased to serve as a temporary building, in which were mounted a 24-inch transit (Troughton and Simms), an equatorial of 5 feet focus (Short), and magnetical and meteorological instruments. Money accumulated, and the present site was purchased in 1841 ; but Harvard
proper dates from the appearance of Donati's comet, which caused much excitement and sufficient enthusiasm to result in the sum of 25,730 dollars being subscribed to furnish Cambridge with a telescope of the largest size. Thus the foundation of the Harvard of to-day was laid. Of the history of Harvard it is needless to speak in the Observatory,' for its enterprise and energy are known to all our readers. The Lick Observatory is fully dealt with, but that, like the modern Harvard, needs no remark here.
One cannot but admire the interest taken in astronomy not only by the heads of colleges, but by the wealthy citizens of the United States, as evidenced by their establishment and endowment of observatories. Mr. Winlock's short article shows that America may be proud of her astronomical institutions, for it displays a record of rapid progress such as can shown by no other country.
The same mail brought us the article on American Telescopes by Mr. Winlock, but this subject was referred to in No. 143, p. 394.
COMETS ZONA AND SPITALER.–The former comet was discovered at Palermo by M. Zona on November 15, and the telegram conveying the news of the discovery reached Vienna about half-past two on the morning of November 17. M. Spitaler at once directed the 27-inch refractor to that part of the sky, and at the first glance saw a faint object in the field. Not being satisfied, as the object
. was much fainter than indicated in the telegram, he searched further and detected the comet Zona. On returning to the first object be found that it had moved in the interval. He was unable to see the comets again till Dec. 4. On Dec. 6 the faint coinet (Spitaler) was observed at Copenhagen, and since then there are several observations, so that no doubt of its nature remains. The elements, however, of the two comets show no relation to each other, Zona having a parabolic and Spitaler an elliptic orbit.
THE ZODIACAL LIGHT.-Prof. C. M. Smith read to the R.S.E. on April 7, some interesting notes of bis observations on the zodiacal light. He has observed the spectrum on many occasions for the last fifteen years in India ?), and for the last eight years with a specially designed spectroscope ; and in all the observations the spectrum has appeared continuous and free from bright lines except during the spring of 1883, and “ ereu then the lines were not seen with sufficient distinctness to make their existence certain.” The most strongly suspected line was about W.L. 558, very near the auroral line at 556-7, which indeed was observed by Angström, in 1867, in the zodiacal light, though Prof. Smith is inclined to think it really belonged to the aurora, whose spectrum at Upsala can often be seen in almost all parts of the sky. Prof. Smith calls attention to the fact that more · accurate information is needed as to the position of the axis of the light, the results of different observers being discordant.
SATURN AND ITS RING.-An interesting monograph on Saturn, the result of fourteen years' work, is contributed by Prof. Asaph Hall as Appendix [I. to the Washington Observations, 1885. The characteristic of this memoir is great caution; and the three drawings of the planet, where a few scanty markings represent all that Prof. Hall can certainly see with a fine telescope, should reassure those who have been dissatisfied with their modest instruments because they could not therewith recognize the elaborate detail described by more imaginative observers. To quote the author's own words :-" The appearance of Saturn in our 26-inch refractor undergoes great changes from night to night, and sometimes even from hour to hour during the same night. Probably these changes are due to variations in our own atmosphere and in the action of the objective, and they do not therefore indicate real changes in the planet. Whenever we have a steady and transparent atmosphere, the outlines of the planet, the faint belts and markings on the Ball, the shadow of the Ball on the Ring, the dusky Ring, and the Cassini division are clear and distinct, and the abnormal phenomena sometimes seen are not visible. Without exception, my experience is that on good nights the planet always has this natural appearance. But on poor nights, when the image is blazing and unsteady, one can see and can imagine many strange things about this wonderful object.”
Prof. Hall finds for the rotation period of the planet, from observations of the white spot (1876 Dec. 7 to 1877 Jan. 2), 10" 14" 238.8 + 28-3 mean time (see Ast. Nach. No. 2146). Careful discussions are also given of the position and dimensions of the Ring.
The notch in the outline of the shadow was never seen at Washington, either by Prof. Hall or his assistant. ture of the outline of the shadow presented an anomaly in 1876 when the convexity appeared to be turned towards the Ball, contrary to what we should expect from geometrical considerations. The notes show that something of this kind was seen after the reappearance of the Ring in 1878. . . . After the Ring was well opened, the curvature of the outline always appeared natural or turned away
from the Ball."
MINOR PLANETS.—The following have been named by M. Charlois :-No. 283, Emma; No. 284, Amelia; No. 285, Regina ; No. 289, Nenetta; No. 293, Brasilia ; No. 294, Felicia.
IN · Engineering' for 1890, Dec. 19, there is a description, with four excellent illustrations, of the photo-telescope for Melbourne, made by Sir H. Grubb, which may be taken as representative of all the English telescopes (Greenwich, the Cape, Oxford, Melbourne, and Sydney) which will take part in the international scheme for charting the heavens.
We notice that Dr. Watts’s “ Index of Spectra” has just been published. It is a work which should prove of the greatest use.
Lieut.-Gen. J. F. TENNANT, C.I.E., R.E., F.R.S.,
President, in the Chair.
Secretaries : E. B. KNOBEL and A. M. W. DOWNING, M.A.
THE Minutes of the previous Meeting were read and confirmed.
Mr. Downing. Fifty-eight presents have been received since the last Meeting ; among those calling for special mention are : • The Scientific Papers of J. Clerk-Maxwell,' 2 vols., presented by the Clerk-Maxwell Memorial Committee; The History of Harvard College Observatory,' by D. W. Baker, presented by the Observatory ; Manuscript Observations of Shooting - Stars, 1873-89,' by W. F. Denning, presented by the Author ; a Bichromate Battery and Ruhmkorff Coil, presented by J. E. II. Peyton, Esq. The thanks of the Meeting were voted for the presents.
Mr. Knobel read a paper by Mr. S. W. Burnham, of the Lick Observatory, on the Proper Motion of H 1968. The faint star was observed and measured by Herschel in 1830 or 1831, the exact date of observation being unknown; but Mr. Burnham has made a series of measures of it during recent years, and finds a regular rate of movement, from which it seems probable that Herschel's observation was made in 1831. Argelander gave the proper motion of the star as o":635 per annum, but this has been shown by Struve to be an over-estimation. Mr. Burnham finds that this proper motion entirely fails to account for the motion of the small star that he has observed, and concludes either that the proper
motion is in error, or the smaller star has a proper motion of its own. No orbital motion can account for the changes in position.
À vote of thanks was accorded for the paper, VOL. XIV.
Page 12
Mr. Fowler. Yes; that seems possible. I only hope we shall learn something from the photographs, if it be only a source of error not suspected before.
Mr. Gregory. I might throw out a suggestion as to the probable cause of error in Mr. Fowler's photographs-one that I thought he would mention. At Kensington a lot of students use the Observatory, and they may have shifted the swing-back of the camera, and it is possible that this caused the duplicity of the lines. I saw Mr. Fowler investigating the photographs previous to his communication. He was as dubious about making it as any one could be, but in some of the photographs the lines were so sharp, and in others the doubling was so obvious, that the duplex character of the star seemed beyond doubt. It is very probable, however, that there is some source of error, and I think it is probably a movement of the swing-back of the camera.
Mr. Fowler. I may say that I never took a photograph without checking the position of the swing-back and of the focussingscrews.
Mr. Knobel, In this negative I fail to see any indication at all of duplicity.
Mr. Fowler, It is very difficult to see anything on the negative in gas-light except under the microscope, and considerable experience is necessary to make out the details.
A Fellow. I may make a suggestion that the doubling is due to halation—the reflection from the back surface of the glass plate.
The President. Then there would be two false lines-one on either side of the original line. The fine lines are said to be double here and the others are comparatively fuzzy, but they are broader. In any case halation would treble the line.
A vote of thanks was passed to Prof. Vogel for his paper.
Mr. Isaac Roberts then read a paper on “ Photographic Evidence of Variability in the Nucleus of the Great Nebula in Andromeda.” The paper was illustrated by means of the lantern.
The photographs may be briefly summarized as follows:-1885, August 30, exposure 30 minutes, the nebula showed no stellar nucleus, and the nova was near the centre; 1886, October 24, exposure 73 minutes, faint stellar nucleus; 1887, October 10, exposure 3 hours, very faint stellar nucleus ; 1887, November 15, exposure 2 hours 35 minutes, no trace of stellar nucleus ; 1888, October 1, exposure 2 hours, no stellar nucleus ; 1888, October 2, exposure 2 hours 32 minutes, no stellar nucleus ; 1888, December 29, exposure 4 hours, no stellar nucleus ; 1890, October 12, exposure 3 hours 5 minutes, no stellar nucleus ; 1890, November 1,
Page 13
of uncertainty. The other paper is on spectroscopic results for the motions of stars in the line of sight, and the results generally show accordance with the previous determinations.
There are, as usual, certain discrepancies which may be due to some remarkable orbital motion in stars, such as have been indicated recently, or they may be due to errors of observation. I should not like to pronounce any definite opinion upon this point. In particular cases I think there is a mixture of two causes of discordance. With reference to these, we hope in a short time to have the 28inch refractor substituted for the 13-inch, and then we shall be able to carry on these observations more effectively and get more accordant results. I have had a letter from Sir IIoward Grubb to say that he has so far figured the 28-inch object-glass that the figuring appears to be perfect so far as 26 inches, and he hopes to be able very soon to get the outside inch of the circumference into good figure; and I think we may look forward to having that object-glass mounted and at work in the present year, and then I trust we may be able to get more satisfactory results.
A vote of thanks was passed for the papers.
Mr. Knobel read a short note from a paper by Mr. Marth entitled “A list of published Lunar Sketches and Photographs arranged according to the Sun's position.”
A vote of thanks was passed to Mr. Marth for his paper. The following papers were announced :-
Prof. H. C. Vogel. “Remarks on Mr. Fowler's note on the duplicity of a Lyræ."
а A. A. Rambaut. - Observations on the Planets Victoria and Sappho made with the Meridian Circle at Dunsink.”
S. W. Burnham. “ The Proper Motion of H 1968.”
Isaac Roberts. “ Photographic evidence of Variability in the Nucleus of the Great Nebula in Andromeda."
Isaac Roberts. “ Mr. Roberts’s new Observatory on Crowborough Hill, Sussex.”
A. Marth. "A List of published Lunar Sketches and Photographs arranged according to the Sun's position.”
Royal Observatory, Greenwich. “Spectroscopic Observations of the Motions of Stars in the Line of Sight made during the Year 1890."
Royal Observatory, Greenwich. “Observations of Occultations of Stars by the Moon, and of Phenomena of Jupiter's Satellites, made during the Year 1890.”
H. H. Turner.“ Note on the recent determination of the Longitude of Paris."
E. J. Stone. “ A comparison between the Greenwich Observations, 1887, and Hansen's Tables as corrected by Prof. Newcomb and Mr. Stone."
Professor Bhuban Mohan Bandyopadhyay, B.A., F.R.H ist.Soc., Christian College, Lucknow, India; Joseph Brooks, Trigonometrical
Page 14
Williams of a dark transit of Satellite No. I on July 26, when the shadow of the satellite appeared double.
The President remarked that the observers at the Lick Observatory thought that they had observed this satellite double or else that it was crossed by a very dark band.
Mr. Sadler believed that Sir James South had observed duplicate shadows of No. 1 Satellite.
Mr. Green then delivered a lecture on the Canals of Mars, illustrated by lantern reproductions of drawings by Schiaparelli
, Boeddicker, Maunder, and himself. Mr. Green doubted the accuracy of Schiaparelli's canal-like markings, and pointed out that it was one thing to be able to see an object and another to be able to draw it correctly and artistically. He illustrated his point by presenting lantern-views of three of Schiaparelli's drawings of the Kaiser Sea made respectively in 1877, 1879, and 1882, and for comparison with them drawings of the same object made in the same years by Boeddicker, Maunder, and himself, and pointed out that, contrary to what might have been reasonably expected, the three drawings by the three different observers resembled each other much more closely than the three by Schiaparelli himself. The same point, he said, could have been established from the drawings of De la Rue, Lockyer, Trouvelot, Terby, Knobel, Neisten, and Kaiser, all of whom had drawn this region practically in the same way: He concluded by repeating that his criticism of Schiaparelli applied, not to his competency as an observer, but to his skill as a draughtsman and an artist.
The President remarked that he had never observed anything at all resembling Schiaparelli's canals on Mars.
Mr. Sadler urged that Schiaparelli was a very gifted astronomer, and in particular a first-class double-star observer, and suggested that possibly atmospheric changes, such as clouds and snowstorms, might account for the altered appearances.
Mr. Lawson remarked that geological changes of seas and continents might be taking place on Mars as they had done on our Earth.
Mr. Maunder (in reply to a question) stated that he had observed a few of the canals as delicate faint shaded lines, but never double; he added that the Kaiser Sea was indicated in drawings by Hooke and Huyghens more than 200 years ago.
Tke following papers were announced :-Two papers by Herr J. Plassmann—the first on Algol,” the second on 66, Tauri;" Mr. Espin on Three new Red Stars ;” Mr. Monck on “ The Connection between Meteors and Comets ;” Mr. J. Webb on “ The Observatory of the late Mr. James Nasmyth.” Two papers, “ Observations of the Spectra of the Sun-spots,” by the Rev. A. L. Cortie, and “ Some Notes on the Solar Prominences of 1890," by Mr. J. Evershed, Jun., were postponed to the next meeting.
Page 15
& Scorpii - 1998.. 0'0768 Doberck. 42 Comæ Ber.- 1728 0:480 O. Struve. 221(B)Ophiuchi-£2173 0·1349 Dunér. i Ophiuchi-£2055 094930
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0139
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Berberich. u? Herculis—A.C. 17
0506 Glasenapp. 2220 Oʻ14853 Celoria. 298
0:51 Dolgorukow. 8 Eqnulci- 2777
O'2011 Wrublewsky. a Centauri-H, 6047 05332 Doberck. 12 Lyncis-9948 0'229
Gore. Σ 228
0:5311
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0-5360 Doberck. u? Herculis - 2220.. 0'3023
Doberck. n Cassiopeiæ-260 05763 Doberck. Σ 1819
o'3052 Casey. ΟΣ 298
0-5836 Celoria. 0-30863 Celoria.
0-5870 Doberck. • Cygni — 2579
0-327 Gore. re? Boötis- 1938. 0-5974
Doberck. Castor-E1110...
0°3292 Doberck. OΣ 41 3-λ Cygni
0.602
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0°3475 Gore.
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0:35 Schaeberle. Sirius...
0:6148 Auwers. B Delphini— 2704 0-3567 Dubiago.
0.6233 Casey. 0:3629 Gore.
$ Aquarii— 2909 0:6518 Doberck. $ Cancri— 1196 0-365 Seeliger. 36 Andromedæ- 73 06537 Doberck. 6 Eridani-H, 612 0°378 Doberck. Σ 2107
0.6688 Casey. 2107 0-3867 Berberich. y Cor. Australis
0:6989 Schiaparelli. y Cor. Bor.- 1967. 0-387 Doberck. & Boötis-1888
097081 Doberck. ΟΣ 20... 0 416 Glasenapp. 44 Boötis- 1909 O'71
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0*7352
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0.896 Thiele,
much like our Sun, and that the component stars of a system are always relatively of the same order of mass. The planets, on the contrary, are of an entirely different order of mass from that of our Sun; and, as Prof. G. H. Darwin has shown, tidal friction has not been of the first importance in the evolution of the planetary system. But the independent investigation above mentioned, wherein the writer has followed methods somewhat analogous to, but also considerably different from, those of Prof. Darwin, seems to show beyond doubt that the secular action of tidal friction has been of the highest importance in the history of binary systems. From this research it appears most highly probable that a binary star was formerly a single nebula, that it split up into a double nebula, and that finally the double nebula separated into two comparable masses, whence by the continual operation of tidal friction the components were wound off to a great mean distance, where they continue to revolve in an orbit greatly enlarged and made very excentric by the action of tidal friction in the bodies of the stars. It is remarkable that if the separation has taken place
Page 16
CORRESPONDENCE.
To the Editors of The Observatory.'
U and T Tauri. GENTLEMEN,-
Reference is made in Miss Clerke's charmingly written volume • The System of the Stars' (p. 183) to a star which his observations in 1862 led the late Mr. Baxendell to regard as variable with a range of rather more than a magnitude, and which was lettered by him U Tauri. The star in question is D.M. + 19°•705, 9*4 mag., its place for 1855'0 being R.A. 4" 13" 208.9, Decl. + 19° 28'•1. The star was first observed by me on Nov. 30, 1863, when I thought it to be of about 9 magnitude. After observing it occasionally in the several following years as a single star, I found it on Dec. 4, 1867, to be a moderately close double, the components equal or nearly so, and measures with the filar micrometer on Dec. 5, 1867, and Feb. 6, 1868, gave P=22°•10 or 202° 10 and D=3":10, the measured distances being larger than my estimates had led me to expect. From a note on p. 3 of Schönfeld's • Zweiter Catalog von veränderlichen Sternen,' the star appears to have been seen double by D’Arrest in the same year, 1867, and observations by Prof. Schönfeld, and Dr. Tietjen with the Berlin refractor on March 21, 1871, gave an estimated distance for the components of 41", with position-angle 190°, the southern star being slightly the fainter of the two.
I have had the star under occasional observation up to the present year, and have generally noted the magnitude of the components, viewed with a low power as one star, about 9:4, occasionally a few tenths brighter. There is no decided colour, with the exception of an observation on Oct. 19, 167, when I have the note" slightly ruddy.” The components have generally
6 appeared to be very nearly equal in magnitude, though the s.p. star has on many occasions been rated as slightly the larger. On two occasions only, Oct. 15 and Dec. 2, 1879, has the n.f. component appeared slightly the brighter of the two.
On Dec. 12, 1888, the s.p. star was noted “ slightly ruddy.” Assuming 94 as the combined magnitude of the pair, the magnitude of each component would be about 10*2. So far as my own observations are concerned there would appear to be no decided evidence of change in the magnitude of the star, and I believe that the late Mr. Baxendell was inclined to doubt whether there may not have been some error in his earlier observations. I bope, however, to keep it under occasional observation.
About 17' to the south of U Tauri, 10% f. lies Hind's remarkable variable T Tauri, D.M. +190706, closely associated with a variable nebula, some interesting observations of which made by Mr. Burnhain with the 36-inch refractor of the Lick Observatory are printed ia the December number of the · Monthly Notices.' T Tauri has a magnitude range of from 9'4 to 13.5 or
Page 17
A.D. 599.
“Cometa hoc anno apparuit.” No comet mentioned even in Williams's Chinese list from A.D. 594 to a.d. 607.
A.D. 1505. “ Cometæ bini annotantur hoc anno; primus apparuit 12 Aprilis, alter mense Augusto." Chambers mentions one in Aries this year, but here we have mention made of two.
To these might be added “the star of marvellous size with one single ray,” described by Matthew, of Westminster, as seen in our land in A.D. 497. [See Journal of British Astr. Assoc.,'Nov. 1890,
Faithfully yours, Melplash Vicarage, Dorset,
S. J. JOHNSON. 1891, Jan. 8.
OBSERVATORIES. STONYHURST.-An interesting paper by Father Cortie on Sunspot Observations made at Stonyhurst in the years 1888-89 appears in the last number of the · Monthly Notices.' The last important contribution to Astronomy which came from this Observatory was the late Father Perry's memoir on photographs and drawings of the Sun (Mem. R. A. S. vol. xlix.), in which he showed so well how there is room for new workers in an apparently well-occupied field. We may remark in passing that a meeting of the Father Perry Memorial Committee will be held on Feb. 13, before the Annual General Meeting of the R. A. S.
Father Cortie's work has been thorough and painstaking. He sums up his conclusions under 20 heads, and it seems scarcely necessary to reproduce them here.
RIO DE JANEIRO.-Volume IV. of the “Annales' has been published in two parts, dated 1889, though we have only lately received them. The second contains meteorological observations only. The first, of 126 pages quarto, contains three sections, viz. : (1) an essay on the distribution of asteroids, written in 1879, in which it is argued that these bodies may be the fragments of a a planet split up, not by one, but by several catastrophes at different points of its orbit-these catastrophes being cometary encounters, of which there is evidence in the distribution of the orbits ; (2) an account of the observations of the transit of Mercury in 1878, previously published; (3) micrometric measures of double stars.
Observations of southern doubles are not very numerous, so that it was with some pleasure we found that M. Cruls bad devoted a considerable time in the years 1879-80 to their measurement with his o":25 refractor. Alas! not more than 5 per cent. of the measures are of permanent value. It is, we believe, generally recognized that measures of new doubles over 30" apart are of very small value. W. Struve limited the distance to 32', and 0. Struve still further reduced it to 16". Other observers have certain
Page 18
Mr. Perigal seconded the motion. The Resolution was agreed to. The President. The special business of this meeting is Mr. Chambers's proposition “ that henceforth the Meetings of the Society be held at 5 P.M., aud that Bye-law 44 be altered accord
Mr. Chambers. I should not have troubled the Society with another motion on this subject so soon after the last, if you
had not refused facilities for a poll of the members on the main question. It is the undoubted right of every Englishman and every lawfully corporate body to bave a poll of absent members.
Mr. Turner. Sir, is this gentleman in order in questioning your ruling?
The President. I think Mr. Chambers is not in order in the the matter; besides that, I will point out, as a matter of fact, that it cannot possibly refer to a case like this. A poll could not be had at this Society, except by means which were unknown to the common law to which
you
refer. Mr. Chambers. I don't wish to discuss that, but I referred to it to explain why I bring the motion up again. I have a perfect right to refer to it as a matter of fact.
Mr. Chambers then proceeded to state the arguments he made use of on previous occasions, quoting as precedents for the change the Royal Society and the British Astronomical Association. meetings are attended by 50 or 60 members out of 600, and if the experiment of alteration to five o'clock meetings results in our attendance falling off very much, I shall be the first to acquiesce to the restoration of the old order of things.”
Rev. A. Freeman. I beg leave to second Mr. Chambers's proposition. I do not care to appear in the character of a stormy petrel, but there is no reason why we should not try this change for a year, and it would certainly remove a good deal of objection on the part of those who feel that the evening meeting is highly inconvenient to them. Our Treasurer made a most important observation at the last discussion of this question, when he pointed out that to observing astronomers it was certainly a consideration to meet in the afternoon rather than the evening. A great number of our older members do not find it advisable to attend evening meetings and go home late, and I notice that at this afternoon - meeting a good many are here who do not attend the evening meetings. Country members naturally feel that if they attend afternoon meetings they are able to go home the same night, whereas after the evening meetings they are not able to get home until 11 or 12 o'clock next day, and a half-day's work, especially on Saturdays, is a serious thing for them.
I think afternoon meetings would induce a more regular attendance of serious working astronomers. I do not mean the amateurs ; I thought we were not a society of amateurs, but a society of professed astronomers. Do not consider only the interests of the
Page 19
want to ask whether the motion to-day is not vexatious, and whether, if it is lost, Mr. Chambers will give notice to bring it forward in two months' time, and so on, every two months ? A word is required to relieve us from anxiety on that point. Another point is, Mr. Freeman said we are not a Society of Amateurs. When I said we are a Society of Amateurs
Mr. Freeman. I was not alluding to you, Mr. Knobel, but to some other Fellow of the Society.
Mr. Knobel. I beg your pardon. I had used the word, I believe, in its proper etymological meaning—that we are a Society who devote ourselves to Astronomy apart from any other consideration than the love of the science itself. I think the
proper
order is that permission should be given to Dr. Schuster to propose his amendinent before it can be submitted and discussed.
The Astronomer Royal. It is quite permissible for any two Fellows to propose and second an amendment without asking permission or putting it to the vote.
Mr. Knobel. The question was first raised when Lord Crawford was in the chair; and the practice was then instituted that an amendment could not be accepted without the Meeting gave permission. That principle was acted upon by Dr. Glaisher when he was in the chair, by the Astronomer Royal, and by our present President.
Mr. Turner. Are you not confusing discussing the question with putting it ?
The President. I must say I am surprised at this objection. I should never have hesitated about it myself. It seems to me as plain as possible that an amendment rising out of a resolution can be made of right and without permission.
Mr. Ranyard. I think the usage is that the leave of the Meeting should be taken that the amendment become the substantive resolution; and if it is proposed to make it the substantive resolution, leave of the Meeting should be asked.
The President. I do not understand that is intended at present. If the amendment is carried the resolution will be abandoned, but not until then.
Mr. Chambers. Then I am willing to withdraw my resolution in favour of Dr. Schuster’s amendment. With regard to what Mr. Knobel has said, I may explain that I brought forward this motion to-day because the President suggested that it was a much more proper one for discussion at an annual meeting than at an ordinary meeting.
A Member. I understand it is impossible for Mr. Chambers to withdraw according to Parliamentary practice. We are called here to discuss this particular question; and I do not see how an amendment concludes the discussion of the original motion.
The President. The original proposition cannot be withdrawn as a matter of right, but only by permission of the Meeting. An amendment can be made as a matter of right.
Page 20
same difficulties, but must in addition explain how the smaller swarm would escape disintegration under the action of the chief
For the smaller swarm would enter on an orbit highly elliptic or hyperbolic. In case the orbit is elliptic, the disintegrating action of the larger swarm, in a comparatively short time, will scatter the meteorites of the smaller swarm along the whole length of its orbit-reduce it (as the Sun reducts a comet) to a train of meteoric dust. Moreover, the observed excentricities of the stellar orbits are in general hardly sufficiently high to support this hypothesis.
Again, it has been suggested that an explosion in the process of separation has rendered the orbit of the detached body so highly excentric. This suggestion of explosions is purely an hypothesis, and we are not able to affirm that such phenomena really take place, except probably in our Sun. But granting that they really take place in nebulæ, it seems very difficult to see how such explosive action could divide a nebula into two nearly equal
It seems more probable that the meteorites of a nebula under such conditions would inerely be scattered in every direction, and that the parts would almost immediately fall back together. But even should the detached parts not immediately reunite to the largest remaining body they would revolve around it as meteoric swarms in excentric orbits, and it is impossible to conceive how, under the disintegrating action of the chief mass, they could ever be gathered into individual small bodies; much less could they be agglomerated into a second large mass.
All the foregoing hypotheses seem, therefore, to encounter fatal objections. I will now venture an hypothesis which demands nothing extraordinary, and rests, moreover, on a dynamical basis.
A homogeneous fluid sphere devoid of rotation is always in equilibrium, however its particles may be arranged with respect to one another. If this sphere be endowed with a slow rotation about any axis, it becomes a spheroid ; here again we may suppose the particles exchanged with one another without any disturbance of the equilibrium. We may regard this homogeneous spheroid as made up of successive infinitely thin layers, all having the same ellipticity. If the rotation of the spheroid is quickened its ellipticity increases, and the ellipticities of all the strata increase with equal rapidity. The particles of a heterogeneous fluid sphere devoid of rotation are in stable equilibrium when, and only when, they are so arranged that the density decreases from the centre to the surface. Such a sphere is composed of successive infinitely thin layers of a uniform density, but the layers decrease in density from the centre to the surface. If now the sphere be endowed with a slow rotation, it passes into a spheroid, and all its layers become spheroidal. But in this case of heterogeneity, the layers do not, as in the case of homogeneity, retain the same ellipticity in passing from the centre to the surface. The ellipticities increase, as is mathematically established by Laplace in the second
Page 21
matical investigation I have profited by a study of Prof. Darwin's extensive tidal researches ; and therefore I should be ungracious, if not indeed in some measure unjust, if I did not acknowledge my special indebtedness to Prof. Darwin for some methods of research employed in his very able papers.
T. J. J. SEE. University, Berlin, Prussia, 1891, Feb. 7.
On the 24th of this month, 115 years will have elapsed since John Harrison departed this life, at the advanced age of 83 ; and although the centenary of his death was not noticed in scientific circles, it certainly was of sufficient importance to have been thus distinguished. There is thus the more
reason for recalling some of the more interesting facts about him on the present
occasion, when several of his productions are about to be forwarded from the Royal Observatory to the approaching Royal Naval Exhibition at Chelsea. It is not my intention to attempt to give anything like a biography of Harrison, but to confine myself to the history and performance of the celebrated instrument, for which he received the Government premium of £20,000 offered in the year 1714.
Often as this instrument has been written about, it has never yet been quite correctly described, from the fact that most writers have not seen it, and others have not had the opportunity of closely inspecting it. Having recently had it entrusted by the present Astronomer Royal to my care for the purpose of cleaning and examination, I feel in a position to write with some confidence on the subject, and also think that I can explain to a considerable extent the reason of the very great unpleasantness which took place between Harrison, the Board of Longitude, and the Astronomer Royal of the time.
The instrument is known as Harrison's fourth timekeeper (some writers have erroneously styled it the third); it is the first which he made in a portable form, the others being more in the form of clocks, in cases some 2 feet square. It is contained in a double silver case 6 inches in diameter, and, although popularly styled a “ chronometer,” is really only a verge watch. The seconds' hand is in the centre, and, from the construction of the escapement, moves in a tremulous manner, which is not convenient for observation. Modern chronometers beat half-seconds.
The three chief features in the instrument are the going fusee, the compensation curb, and the remontoire train. The importance of the first two cannot be over estimated, but the value of the last is doubtful, although it appears to have been the leading idea in Harrison's mind.
Looking back on his work, we consider in these days that his eztapement was on a wrong principle, and that he started from a bad foundation in using it, apart from the difliculty of making it properly. It is affected, more than any other, by inequalities in the power of the mainspring, so he added the secondary force of the remontoire, in order to communicate a constant impetus to the escapement at intervals of seven and a half seconds. The ingenuity displayed in the arrangement is simply marvellous, but so much extra friction is introduced by the addition of the remon-; toire train that it is doubtful whether the extra force (which is imparted by the alternate coiling and uncoiling of a spring) more than counterbalances it. All the acting parts of the instrument are closely concealed by ornamental brass work, so that it is impossible to examine them without partly taking it to pieces, and I venture to assume that this was one cause why the Board of Longitude were prejudiced against the instrument when it first came before them. I must not omit to state, however, that the workmanship is perfect throughout, the wheels and pinions are beautifully cut, and the steel has been hardened and tempered in the most scientific manner possible, otherwise the pivots and springs would not stand the manipulation which is necessary to get them in their places. High polish has not been aimed at, but everything has been done with a view to utility. plate is engraved “ John Harrison & Son, 1759."
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stated by several writers that this copy, by Larcum Kendall, was used by Captain Cook on his second and third voyages, the fact being that it has never seen actual service like the original. Captain Cook's--made by Larcum Kendall in 1771–is constructed on much simpler principles, and has no remontoire action. I was entrusted with the task of cleaning it at the end of 1889 by the Council of the Royal United Service Institution. Unfortunately, the escapement is worn out. But to return to Harrison's. On the 5th of May, 1766, it was handed over by the Lords of the Admiralty to the custody of the Astronomer Royal, for the purpose of being tested at the Royal Observatory for a period of ten months, viz., to March 4, 1767. It fully sustained the reputation which it had gained on the West India voyages, as its rate in ordinary temperatures was exceedingly uniform—the first day of rating it gained 17:6, and the last 18-7; but when the temperature fell to 26° it gained nothing, which, unfortunately for Harrison, was the opposite to what he said it would do. It is a proof, however, that he had so far mastered the principles of compensation as to actually reverse the usual effects of cold on the going of a watch. The Astronomer Royal finally reported on the instrument as follows :- “ That Mr. Harrison's watch cannot be depended upon to keep the longitude within a degree in a West Ludia
voyage of 6 weeks, nor to keep the longitude within half a degree for more than a fortnight, and then it must be kept in a place where the thermometer is always some degrees
above freezing: that in case the cold amounts to freezing, the watch cannot be depended upon to keep the longitude within half a degree for more than a few days, and perbaps not so long, if the cold be very intense : nevertheless, that it is a useful invention, and, in conjunction with the observations of the distance of the moon from the sun and the fixed stars, may be of considerable advantage to Navigation.” The Astronomer Royal also took exception to the great increase of rate since the voyage; in the interval the instrument had been cleaned, and he considered that the former rate should have been maintained. Harrison was requested by the Board of Longitude to make two similar instruments for testing at the Royal Observatory, but it does not appear that this condition was complied with. He made one for the King, which after ten weeks' trial at his private observatory at Richmond, is said to have varied only 42 seconds. It is currently believed that His Majesty personally interested himself on Harrison's behalf, and that the remainder of the reward was paid over in consequence of his intervention. As a matter of fact, the instruments had become obsolete before they were paid for. Mudge, Arnold, and Earnshaw were all in the field, appropriating Harrison's and each other's improvements indiscriminately.
When Captain Cook sailed on his second expedition in 1772, he had three of Arnold's with him, in addition to the historic one of Kendall's already mentioned. Two of these are in the possession
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number of Australian Meteorological Stations reporting by telegraph, as the telegraphic authorities may find the necessary work too burdensome. This is a fine opportunity for some one to make disparaging remarks about Meteorology.
WASHINGTON.-The U.S. Naval Observatory is apparently suffering from a dearth of workers. Naval Officers have recently not been spared in sufficient quantities, and consequently the work is behind. Thus the transit-circle work for 1885 is in print; the reductions for 1886 are nearly finished, and the apparent place reductions for 1887 are more than half completed : but those for 1888, 1889, and 1890 have not been commenced. Prof. Asaph Hall has been at work with the Equatorial on the satellites of Saturn and Mars, and on double stars, but here, again, computing help is wanted. Mr. Paul has chiefly worked at his own variable s Antliæ, whose period he finds to be 7h 46m 48*0 within a fraction of a seco
econd, barely a third of that of the next shortest, U Ophiuchi. The report of Mr. Harkness rather takes away our breath, and we append it in full, for the benefit of those who like this sensation :
“SIR, -I have the honour to report that during the year ending June 30, 1890, I had no assistants, and nearly all my time was devoted to investigations and computations connected with my work on the solar parallax and its related constants.
“ As is well known, there exists a vast mass of astronomical, geodetic, gravitational, and tidal observations which have hitherto been discussed piece-meal, and have therefore yielded only isolated results. My object has been to deal with these observations as a whole, and to derive from them a homogeneous system of constants satisfying all the conditions imposed by our present theoretical knowledge. For that purpose recourse was had to the method of least squares, and a suitable system of simultaneous conditional equations was formed. The constants involved in these equations were the size of the Earth, the lengths of the seconds pendulum, the sidereal month and the sidereal year, the ratio of the mean motions of the Earth and Moon, the eccentricities of the orbits of the Earth and Moon, the inclination of the Moon's orbit, the rate of regression of its node, and certain co-efficients occurring in the lunar theory, and the first step was to ascertain the best values of these quantities. The observed quantities to be corrected by the least-square adjustment were the solar and lunar parallaxes, the constants of precession and nutation, the parallactic inequality of the Moon's motion, the lunar inequality of the Earth's motion, the constant of aberration, the light equation, the velocity of light, the flattening of the Earth, the masses of the Earth and Moon, and, indirectly, the masses of Mercury and Venus. In order to obtain proper values of these quantities for use in the conditional equations it was necessary to collect and discuss all the available astronomical, geodetic, gravitational, and tidal data ; and, as this discussion in
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Mr. Knobel read a paper by Mr. A. A. Rimbaut “ On the determination of Double-Star Orbits from Spectroscopic Observations of the velocity in the Line of Sight.”
Since the beautiful results of Professor Pickering at Harvard on B Auriga and ( Ursa Majoris, and Prof. Vogel at Potsdam on Algol and a Virginis, I have been examining the problem' of determination of the orbit of a binary star from spectroscopic observations alone. The curve given in Prof. Pickering's report on the Henry Draper Memorial shows that with 3 Aurigæ there is a periodic displacement occurring in about four days. In drawing the curve of velocities from the data given there are two conditions that must be fulfilled. After giving these conditions Mr. Rambaut demonstrates his inethod of determination of the form of the orbit, and tests his elements with the data given for B Aurigæ, the errors being well within those of measurement.
One point which the examination of the question seems to indicate very clearly is that observations should be taken, not so much at equal intervals of time, but so that the points derived from them may be as far as possible equally thick along all parts of the curve of velocities, or, in other words, so that all parts of the curve may
be determined with equal accuracy It is important to fix the exact time of coincidence, as well as the epoch at which the velocity is the arithmetical mean between its two extreme values. With stars of the Algol type, where only one component is bright, displacement is measured by comparison with an artificial line; the whole velocity is composed of the orbital motion as well as absolute motion in line of sight. With sufficient and accurate observations it will be possible to separate orbital from absolute motion ; but the materials at present available for Algol are almost ludicrously inadequate. The observations on which the curve of velocities for Algol depend are so few that the figures are little better than mere guesses. A vote of thanks was accorded Mr. Rambaut for his
paper. Mr. Knobel read a paper by Mr. S. W. Burnham on “The Companions of Aldebaran.
The nearest companion discovered by Mr. Burnham with the 18.2-inch Chicago refractor in 1877 is shown by later measures with the Lick 36-inch to have the same proper motion as the principal star, for both distance and position-angle are unchanged. The more distant Herschel companion has been observed for more than a hundred years, and its changes in position were ascribed solely to proper motion of the principal star; but Flammarion has shown that this will not wholly account for the changes, and that the fainter star has a proper motion of its own in a different direction. In 1888 the Herschel companion was found to be double with the 36-inch refractor, the distance between the stars being 2". From the measures given it appears
that the proper
motion is common to both these stars; but more observations are required to settle this.
Mr. Knobel read another paper by Mr. S. W. Burnham on the Orbit of a Pegasi.
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that the change was in the same direction, but perhaps greater in extent.
Mr. Plummer. I think it would be interesting to know whether, in the opinions of the expert astronomers at Greenwich, there is any real evidence of a change in the latitude. The evidence I have seen does not seem conclusive to my mind, owing to its being mixed up with the question of the constant of aberration.
Mr. Turner. I believe the measures M. Bakhuyzen uses to deduce his results are first corrected to the new aberration.
Mr. Downing. But the correction is very small. Some years ago a proposal was made by some astronomer that to detect an annual period for this change of latitude, if it really exists, observations should be made at different parts of the year at observatories having the same latitude but of different longitude. I believe a programme of this kind was drawn up and a proposal made that three observatories in Europe and three in America should cooperate. That seems the most satisfactory way of arriving at a conclusion upon this matter, but I am sorry to say that so far as I know nothing has been done to carry out this much desired work.
Mr. Stone. I am afraid in questions of this kind there is a difficulty in arriving at any definite results. If you have your thermometers in the observatory a considerable distance from each other you cannot be sure you have them in positions that will give you the right refraction when you are dealing with such small quantities as those involved here. The real difliculty is the question of temperature, and there can be no doubt that this introduces uncertainties when you come to these small quantities, the uncertainties probably depending upon the exposure of the thermometer. I do not know of any method of deciding what is the proper exposure to give to a thermometer.
Mr. Turner. It is only fair to M. Bakhuyzen to say that he entered upon the discussion of the changes of latitude after a careful consideration and discussion of temperature, and after making every possible consideration for the thermometers exposed in different directions.
The President. I suppose there will always be a difference of opinion upon these small points until we find some perfect mode of providing for temperature, and there will probably always be some doubt as to which is the proper way of measuring that. In the meanwhile we may express our thanks to M. Bakhuyzen for the very interesting paper
he has sent us. The Astronomer Royal then read his paper entitled “Notes on the Preparations for the Work of the Astrophotographic Chart.” I thought it might be interesting to Fellows to know, as we are now at Greenwich beginning operations for the Astrophotographic Chart, what the state of affairs is, and how far we have got, because it is a matter in which one must proceed tentatively, and there is a great deal to be worked out. With Mr. Turner's assistance this paper has been drawn up on the subject, and has been divided into different heads. The first important matter was to have a catalogue of guiding-stars, by means of which the telescope might be fixed with the centre of the plate in a definite position, so that we should have the centre of each plate in the selected position in the heavens, and thus be able to form a map. That is a matter which is not so simple as it appears at first. Prof. Bakhuyzen went into the question, and from his trials on a particular zone he came to the conclusion that if he went as far as 22' from the centre, he would be able to get a sufficiently bright guiding-star within that distance in almost all cases; but we found there would be a great advantage in extending that distance from the centre. Mr. Hollis, who has had charge of this work, has tried the two plans, and finds there is a distinct advantage in taking 30' as the limiting distance-that is to say, we are not obliged to take such faint stars. With the Greenwich 13-inch Equatorial there is a 10-inch guiding-telescope, and it is proposed to take, when possible, a star not fainter than 9th mag.; but in some cases it is necessary to go down to 9], using, in such cases, the star of brighter magnitude which is nearest to the centre as an alternative guiding-star. In the paper which has been drawn up the numbers of guiding-stars are given of the different magnitudes, according as you take 22' radius or 30' radius. In the zone with wbich we are concerned there will be go stars of the g} mag. of Argelander (which really means anything down to roth mag.) with 22' as limiting radius, and there are only 28 of these stars with 30' radius, so there is an obvious advantage in extending the distance from the centre. There is another point that has to be borne in mind, and which is obvious as soon as we begin to think of it, and that is that in order to get the position of the centre of the plate accurately, we must allow for the effect of the projection of the sphere on the tangent plane of the plate in taking the rectangular co-ordinates of the guiding-stars. The next is the réseau which is to be printed on the plate. Two very fine réseaux on glass have been received from Prof. Vogel, and one has been mounted. This work has proceeded slowly owing to the necessity of testing things after each step, and each particular step bas taken some time to properly arrange. The réseau consists of two sets of lines, ruled at right angles to each other on the silvered surface of a glass plate, the lines being 5 millimetres apart. The lines are cut through the silver on the glass plate; and the sensitive plate is put nearly in contact with the réseau and placed in front of the object-glass of the photographic telescope. By means of an incandescent electric lamp placed in the focus of the object-glass the réseau is printed on the sensitive plate, but is not developed until the plate has been exposed on the stars, the stars and the lines of the réseau being developed at the same time. The réseau thus serves to give reference lines for the stars, and also for the determination of any distortion of the film. There can be no doubt, from our experiments, that this method is perfectly successful, very beautiful
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The Astronomer Royal. A disk of 2" diameter would be given for a 14th mag. star with 12 minutes exposure according to our results, but in our notes we say 25 to 30 minutes will probably be required to give satisfactory disks.
Mr. Plummer. The conclusion I have come to is that go minutes are necessary for a 14th mag. star on an average night.
The Astronomer Royal. That exposure is impracticable.
Mr. Ranyard. What plates have you been using ?
Mr. Plummer. The same as the Astronomer Roval. The illness of Prof. Pritchard, in which we all sympathize with him [hear, hear], has prevented me from putting our notes fully before the Society.
Mr. Knobel. Can you give us any idea of the probable error of gradation of the réseau ? that would be interesting.
The Astronomer Royal. We had a micrometer, used for measuring the Transit of Venus photographs, altered for this work, so that our measurements must not be considered as absolute or final.
The millimetre scale of the instrument is not absolutely accurate, but, as far as the errors of this are known, we find the réseau errors are too small for us to detect with absolute certainty ; they are about the same as the prubable errors of the determination.
Mr. Plummer. Do the Greenwich authorities find that the same magnitude is impressed in the same time all over the plate ? I found a decided want of smaller stars as I passed from the centre of the plate, and this at 50' or 60' became more emphasized and accentuated.
The Astronomer Royal. This would entirely depend upon the position of the plane of the plate with regard to the focal plane of the telescope. At Greenwich and at Paris the plate is put well within the focus for centre of field so as to equalize the error from curvature of the field. With this precaution you will get satisfactory results for a region 50' or 60' from the centre of the field. I should like to know the exact position of the plate with regard to the focal plane at Oxford, as if it is inside the focal plane I do not think the objection raised by Mr. Plummer is valid. On several plates taken at Greenwich, which were specially compared with Argelander's charts, the images of the fainter stars in Argelander were distinctly visible up to the edge of the plate.
Mr. Ranyard. Plates differ with different instruments. I bave been examining plates taken by Mr. Russell at Sydney, and in those the falling-off in number is exaggerated owing to the larger field. This falling-off must depend upon the correction of the photographic object-glasses.
The Astronomer Royal. I was speaking of what we may call a perfect object-glass for photographic purposes—that is, one that will give a lateral image that is symmetrical, not only with reference to the radial plane, but to the transverse plave.
The President. Has the Astronomer Royal heard of an objectglass by Steinheil, who claims that it gives circular images ?