The Astronomical Register..

No. 176.

AUGUST.

1877.

THE ROYAL ASTRONOMICAL SOCIETY.

serious a

No one can regret more than we do that there should be serious disagreements among the Fellows of the Royal Astronomical Society, but we cannot for a moment doubt that in so question as that of altering the Bye-laws of one of the oldest of the so-called learned societies, it was both undignified and unwise that there should have been even the appearance of haste. It seems strange that it was expected by the most sanguine and intrepid of the proposers of the strong measure laid before the last meeting, that it was in any way possible to pass it in an hour or so; in other words, without discussion. There seems to have been a curious exhibition of impatience on the part of some members of the Council, which was hardly justified by the merits of the case. Of course, if the Council of the Astronomical Society is to be considered the Society itself, and if the Fellows are to be so many puppets to nod their heads as the Council bids them, and to pass without consideration or discussion what has seemed good to the "Patres conscripti," then of course they merited the ire of some of those who have had to do with these proposed alterations. But if the general body of Fellows has any respect for itself, it must have a real voice in so serious a matter concerning the well-being of the Society. There cannot be the slightest question in our minds that the Royal Astronomical Society should never have been called upon to pass sweeping alterations in their Bye-laws without being able

to

propose even verbal alterations. The whole affair bears on its

face too much the appearance of the Council trying to ride the high horse over the other Fellows. "Take them all or you shall not have them at all; we have decided that these alterations are absolutely necessary, and that the form in which we propose them is the best which could possibly be made." Now this seems to us a very unwise and very unfair way of treating the subject. who doubt the wisdom of any change, and there

There are many

VOL. XV.

is much to be said on their side. These might of course have voted without discussion against the alterations, but there are probably still more who think that some change, if not necessary, is still likely to conduce to the advantage of the Society. It was simply absurd to suppose that, if they could help it, the Fellows would consent to pass alterations in which they had no voice, unless they entirely agreed with them.

If the Council are placed in an unpleasant position, it is surely their own fault. It must have been a most unbusinesslike proceeding even to attempt to force these resolutions, the result only of a compromise, upon the general body of Fellows. It was unbusinesslike, because it was unfair, and we may add foolish; for however well the subject might have been considered, surely it was most unwise to preclude the possibility of making the slightest even verbal alteration. The Council must consider themselves to be very wise indeed, if in a matter, not of astronomical, but of ordinary business, they did not expect to gain any advantage from the advice of one single Fellow not a member of the Council. In matters of pure astronomy we are ready to admit that the ordinary Fellows are not always competent to form an opinion. If this were not so we should not, as we occasionally do, excite the astonishment of outsiders at some of the gentlemen we elect as our Council, and at our rejection of others of whom any Society out of England might be proud. This however is merely a matter of transacting business, and there are very many Fellows with only a general interest in matters astronomical, who are far more competent to give a valuable opinion upon it, than the most careful and admirable of observers or the best mathematicians and computers of the body. We should have thought that the Council would not only have been willing, but have desired, that their acts and propositions should be discussed by the Fellows in the fullest and freest way possible.

Lord Lindsay showed simply very good sense in moving that the consideration of the question should be deferred to a time when it might be fully and thoroughly discussed. If he had not done so, we happen to know that there are others who would; but the proposal could not have fallen into better hands. We shall be glad to receive communications from the Fellows upon the subject.

The observations inade on the companion of Sirius, discovered in 1862, are now rather numerous and extend over an arc

extensive enough to allow us to examine whether this companion follows strictly the orbit obtained by theory.

It will be remembered that the periodical irregularities observed in the proper motion of Sirius, even as far back as 1844, led Bessel to suppose that there was in the vicinity of this brilliant star an invisible disturbing body, to whose influence these irregularities might be attributed. They especially are remarkable in right ascension: the difference between the mean right ascension and the actual right ascension according to observations has been from+0,0588. in 1842, and of 0,1338. in 1850. In 1851 Peters, following the hypothesis of Bessel, calculated the theoretical orbit which would agree with the observed perturbations, and found:

Passage through the inferior apsis

Mean annual motion

Period

Eccentricity

1791'431
7°, 1865.

50 years, 01.

0,7994.

Eleven years later, on the 31st of January, 1862, Alvan Clarke found out the companion as he turned upon Sirius his new objective of 47 centimetres. The satellite was plunged in the rays of the brilliant star, but, nevertheless, was easily perceptible. It is a star of ninth mag. Since then it has been carefully observed every year.

It was to be found almost exactly at the east, and its position agreed pretty well with the theoretical position. In 1864 Auwers made a new calculation of the orbit according to the whole of the observations of the proper motion, and found the following elements, which do not differ much from the first, and

confirm them:

Passing by the inferior apsis

Mean annual motion

Period
Eccentricity.

1793 890.
7°,28475.
49 years, 418.
0,6010.

The last orbit calculated by Auwers, put in the form of orbits of double stars (see Nature of 30th March, 1876), and offered as definitive, is the following one:

1843,275 61° 57''8 18 549

P = 49 years '399

According to these elements the limits of distance should have been 2", 31, at 302, 5, in 1841, 84 and 11", 23, at 71°,7 in 1870, 13 and the ephemeris is

Now, here is the series of micrometrical measurements which I have collected and inserted in my Catalogue of double stars in motion. 85± 10± AC. 1866,24 78,6 10,34 Tu.

AC., Alvan Clark; Bo., Bond; Ru., Rutherfurd; Ls., Lassell; Se., Secchi; 2, O. Struve; Mr., Marth; Da., Dawes; Wi., Winnecke; Fo.,

Förster Ti., Tietjen; En., Engelmann; Kn., Knott; Bh., Bruhns; Fa., Eatsman; Ha., Hall; Nw., Newcomb; Tu., Tuttle; Vo., Vogel; Br., Brunnow; Du., Dunér; Pe., Peters; Ws., Wilson & Seabroke; Ho., Holden.

If we compare the observations with the ephemeris we see that the angle diminishes more quickly than it had been announced, while the distance has kept on increasing from 1870 instead of having reached the maximum in that year, as was indicated by the calculations of the orbit. This is very easily proved by a single glance at the drawing which I have made, on the exaggerated scale of one centimetre for one second. observed apparent orbit crosses from 1869 the calculated apparent orbit, and projects outside, following a quite different course which will be more extended and less eccentric.

The

The

observed companion certainly belongs to Sirius, and does not form with the brilliant star a mere group perspective; for, if it were so, Sirius would have gone from it in the direction indicated by the arrow, which represents its proper motion (A.R.-0"503 [-os.,035 x 15 x cos D.]; D.P. + 1,23; result out=1",33). The mean angular motion is only 2°15 and can be considered as having been regular,* taking into consideration the rather sensible errors of observation in this pair so difficult of measurement. If that were the mean general motion, the revolution of the satellite would be much longer than it ought to be (totally) to agree with disturbers, it would be increased to about 167 years. But the arc passed over is still too small for us to decide anything on that point, and as the irregularities of motion require the period to be 49 years, we are led to conclude, either that the observed companion will accelerate its motion and will be found at the west in 1892, or that there is another disturbing body not yet discovered, which is nearer and more rapid.

the

proper

We must reserve any conclusion on the existence of one or more satellites as well as on any difference of period between the observed orbit and the calculated one; but the undeniable fact to be deduced is, that the observed positions do not agree with those of the ephemeris, and that the orbit which results differs from that

calculated.

THE GERMAN ASTROPHYSICAL OBSERVATORY

NEAR POTSDAM.

This observatory is being erected at some distance to the south of the town of Potsdam, on a wooded eminence, which is called the Telegraphenberg (Telegraph Hill). There could hardly be *Yet we notice a rather striking tardation from 1866 to 1869, and an acceleration from 1869 to 1871.