March 22, 1900J 



NA TURE 



4S7 



Miiepoix, found a planet in December 1804 and observed 



I', for three weeks, without its identity with Ceres being 



ticed either by him or by Lalande, who christened the 



V planet by the name of the discoverer, and sent the 



ervations to Germany. Already, in 1802, Gauss sent 



bers a sketch of his new method of computing elliptic 



nients, and after being more than once urged to bring 



a detailed account, he began to work at the "Theoria 



.otus Corporum Ccelestium " early in 1806, and had it 



nearly finished in March 1807, when the discovery of 



\ esta gave him a welcome opportunity to apply his 



method once more, and particularly to compute an orbit 



of small inclination from four observations. 



As comets were the favourite celestial objects of 

 Olbers, observations and computations on them were 

 on every occasion exchanged by the two correspondents. 

 In 1806 we find Gauss pointing out that Olbers' method 

 of finding a parabolic orbit fails when the direction of 

 the apparent motion of the comet nearly passes through 

 the place of the sun, a fact which Olbers had, however, 

 already noticed, having had his attention drawn to it by 

 a remark of La Place, which had reached him through 

 liurckhardt, and apparently in a mutilated forrn. 



Unlike most great mathematicians, Gauss was exceed- 

 ingly fond of observatory work, and before his appoint- 

 ment to the Gdttingen professorship (in 1807) he re- 

 peatedly expressed the wish to become attached to some 

 large observatory, and be relieved from teaching and 

 lecturing, for which he felt no taste. Owing to the dis- 

 turbed times, the building of the new observatory at 

 Gottingen made very little progress for some years, and 

 Gauss had only the old instruments of Tobias Mayer's 

 Observatory at his disposal. He made diligent use of 

 a small refractor furnished with an annular micrometer ; 

 and in January 1808, shortly before Bessel published his 

 paper on this subject. Gauss communicated to Olbers 

 very convenient formula? for correcting observations with 

 this micrometer for the effect of refraction, based on the 

 idea that within the ring there is visible a part of the 

 sky which may be considered as an ellipse with the major 

 axis vertical. He never published anything on this sub- 

 ject ; but in 1830 C. A. F. Peters gave formula? based 

 on the same idea, though this is not explicitly stated. 

 Again, in 1874, Dr. C. Schrader, in an inaugural disser- 

 tation issued at Gottingen, developed similar formulas 

 without alluding to Gauss, whose ideas on this, as on other 

 methods of reducing observations, have doubtless not 

 been forgotten at the Gottingen Observatory. In a re- 

 view of this paper {Vierfeljahrschri/t, x. p. 214), Prof. 

 Schonfeld, however, called attention to Gauss' method, 

 with which he had become acquainted through MS. 

 notes of one of Gauss' lectures. The tardy publication 

 of the method in the present volume is most welcome. 

 We notice also some interesting remarks about a small 

 heliometer by Fraunhofer and Reichenbach, received in 

 1814, and an instructive comparison between it and the 

 old so-called object glass micrometers. This heliometer 

 was in 1874 and 1882 still capable of doing good work 

 in connection with the transits of Venus. 



Towards the end of the volume we find Gauss very 



much occupied with the three new meridian instruments 



mounted in 181S and 1819, of which the Repsold transit 



circle of seven feet focal length and four inches aperture, 



NO. 1586, VOL. 61] 



with a circle read by two microscopes, deserves special 

 mention as the first modern instrument of its kind. It 

 banished mural quadrants and mural circles from the 

 Continent ; but, unfortunately, English astronomers 

 thought it necessary to wait a good many years yet 

 before adopting the idea put forward by Romer towards 

 the end of the seventeenth century. In 1817 Gauss 

 expresses the hope that a circle of this kind may soon 

 be established at the Cape, an idea warmly taken up 

 by Olbers, and which bore fruit a few years later when 

 the Royal Observatory at the Cape of Good Hope was 

 established. The Gottingen instruments were almost 

 immediately put to good use in the continuation of the 

 Danish geodetic survey through Hanover, which occupied 

 Gauss (perhaps far too much, as a smaller mind could have 

 done most of the work equally well) for a number of years. 

 The political events of the time are not infrequently 

 alluded to, though with a certain caution, as it was 

 doubtless not safe to be too outspoken even in private 

 letters. In 1807, we learn, the Leipzig Academy pro- 

 posed to make a Napoleon constellation of the central 

 part of Orion, and Gauss remarks that this chopping up 

 of old star groups would fitly correspond to the state of 

 things on the earth at that moment. Gottingen formed 

 part of the ephemeral kingdom of Westphalia ; while 

 Bremen was, in December 1810, annexed to the French 

 Empire, and formed part of the Department des Bouches 

 du Weser, to the great grief of Olbers, who clung to the 

 old institutions of the free town. He askes Gauss, in 

 August 181 1, to tell him as many astronomical news as 

 possible, as scientific and medical journals (except 

 French ones) are strictly forbidden in Bremen. As a 

 member of the Legislative Corps, he had to pay two 

 lengthy visits to Paris in 18 12 and 181 3, whence he 

 wrote some interesting letters about the meetings of the 

 Academy and the Bureau des Longitudes. 



The editor has confined himself to seeing the letters 

 through the press, and appears to have performed this 

 task well ; we have only noticed a curious error on p. 504, 

 Bredebour for Lerebours. But he has not given any 

 bibliographical or other references, for which the contents 

 of the letters offer many opportunities, but has only in 

 footnotes given some references to Gauss' collected works 

 and the correspondence between Olbers and Bessel. In 

 one of his few footnotes he makes a mistake, which looks 

 strange in a German book (p. 522) ; it was in April 18 13, 

 during the war of liberation, that Schroter's Observatory 

 was destroyed, and not in December 1812, when every- 

 thing was quiet throughout Germany. As an example 

 of a place where a footnote ought to have been inserted, 

 we may mention p. 337. Gauss here states that a star 

 occuring in the Histoire Celeste is missing, and suggests 

 that it may have been Vesta. This star (LL46570) is not 

 missing, its place is quite correct, and so far no variability 

 seems to have been detected. 



For nearly fifty years the correspondence between 

 Olbers and Bessel has been an astronomical classic, sup- 

 plemented in 1880 by the publication of that of Bessel and 

 Gauss. The chain is now being completed by the corre- 

 spondence between Olbers and Gauss, the promised 

 second half of which will no doubt give much valuable 

 information about Gauss' geodetic and magnetic work. 



J. L. E. Drryer. 



