642 



NATURE 



[January 13, 192 1 



issued at tjuartfrly intervals. It will give the full 

 titles of books, pamphlets, theses, original articles in 

 journals, and transactions of medical and scientific 

 societies. In the case of contributions printed in the 

 lesser-known l;inguages, their titles will be rendered 

 into English. Kach number will contain a gi'neral 

 table of contents, and as soon as possible after the 

 completion of each volume an "Annual Inde.x of 

 .Vuthors " will be issued. Subscriptions to the work 

 should be sent direct to the Carnegie Institution of 

 Washington, Washington, D.C., U.S..^. 



\ USEFUL catalogue (No. 86) of second-hand books 

 and journals relating to zoological subjects has just 

 been received from Messrs. Dulau and Co., Ltd., 

 34 Margaret Street, W.i. It contains upwards of 

 iioo titles, .\mong the works listed we notice a first 



edition of "The Origin of Species," "The British 

 Museum Catalogue of Birds" (27 vols.), Dresser's 

 "A History of the Birds of Europe," and Reeve and 

 Sowerby's "Conchologia Iconica"; also complete sets 

 of the Zoologist and the Entomologists' Record and 

 Journal of Variation. Copies of the catalogue can 

 be obtained from the publishers. 



The latest catalogue (No. 361) of secondhand books 

 and periodicals issued by Messrs. Bernard Quaritch, 

 Ltd., II Grafton Street, W. 1, is mainly of a general 

 character, but lengthy sections devoted to botany, 

 natural history, and Oriental literature make it worthy 

 of the attention of readers of a scientific journal such 

 as Nature. As is usual with catalogues circulated by 

 Messrs. Quaritch, many rare volumes are offered for 

 sale. 



Our Astronomical Column. 



Skjellerup's Comet. — It appears that this comet 

 was first detected by Mr. C. J. Taylor at the Cape 

 on December 8, Mr. Skjellerup finding it indepen- 

 dently on December 11. It should, therefore, be called 

 "Tavlor-Skjellerup." Mr. R. L. Waterfield observed 

 the comet at Hereford with a 4-in. refractor. His 

 positions are not micrometrical, but eye-estimations 

 from adjacent B.D. stars. : 



These agree within some 5' with Mr. VV'ood's 

 ephemeris, which is continued below (for Greenwich 

 midnight) : 



R.A. N. Decl. X-og r Log A 



h. ir. s. o , 



Jan. 16 It 041 3324 01093 95783 



20 II 7 17 3622 01192 96095 



24 II 12 3 3851 01293 96406 

 28 II 15 II 4056 01398 9-6715. 



Feb. I II 1648 4240 01506 97024 



5 II 17 28 44 3 0-1615 97328 



9 II 1654 45 9 0172b 97626 



13 " 15 52 45 55 "•1837 97920 



17 II 14 16 4628 01948 9-8210 



21 II II 10 4653 02055 98486 

 History of the Chronometer. — Lt.-Comdr. R. T. 



Gould read a paper on this subject at the meeting of 

 the Royal Geographical Society on December 13 

 which presents very vividly the tremendous revolution 

 in navigation which this invention implied. He 

 recalls .'\nson's disastrous voyage in 1741, when a 

 mistake in the longitude caused such delay in making 

 port that half the crew died of scurvy, .\fter describ- 

 ing earlier abortive attempts, he proceeds to the 

 famous prize of 20,000!. offered by the British Govern- 

 ment in 1713, and won fifty years later by John 

 Harrison, though he had undeniably earned the reward 

 long before — a delay which reflected great discredit 

 on the Government. The paper dwells on the inven- 

 tive genius and constructive skill which Harrison con- 

 tinued to display ; indeed, the performance of his 

 various machines would be creditable at the present 

 day. It is pointed out that his invention of the main- 

 taining spring has never been superseded, and that 

 the " remontoir " device for equalising the force on 

 the escape-wheel, though no longer required on 

 chronometers, has been introduced into the Riefler 



NO. 2672, VOL. 106] 



clock. Several anecdotes are given of Harrison's, 

 voyages, in which he frequently corrected the reckon- 

 ing of the captain and officers ; on one occasion he 

 saved the ship from missing the Island of Madeira, 

 to the great relief of the crew, who were short of 

 beer. 



Capt. Cook used a duplicate of Harrison's watch 

 made by Kendall, and noted that "our longitudes can 

 never be erroneous while we have so good a guide." 

 The paper goes on to describe the work of Mudge, 

 Le Roy, Berthoud, .Arnold, and Earnshaw, and con- 

 cludes by referring to the recent introduction of wire- 

 less telegraphy for time-distribution and direction- 

 finding. The latter have effected a revolution in 

 navigation almost as far-reaching as the invention of 

 the chronometer. 



Thf, Pi.a.netesimal Hypothesis. — This hypothesis, 

 enunciated by Profs. Moulton and Chamberlin, has 

 been favourably received by a number of writers, 

 including Dr. Jeans in his recent work on cosmo- 

 gony. The Scientific Monthly for last May contains 

 an interesting critique on the theory bv Prof. 

 Reginald .\. Daly, of Harvard Iniversity. Prof. Dalv 

 suggests some amendments to Chamberlin's views 

 on the later stages in the earth's development. 

 Chamberlin concluded that the earth's temperature 

 was never very high, that its mass has slowly in- 

 creased through the impact of planetesimal dustj and 

 that oceans existed when it had onlv one-third of its 

 present mass. Prof. Daly argues (i) that the matter 

 composing the different planets is likely to be the 

 same in the main, and (2) that the low density of the 

 giant planets, combined with the phenomena ob- 

 served on their surfaces, gives conclusive evidence of 

 high temperature. He thinks that the earth was 

 molten, if not gaseous, during its early history. An 

 argument is also drawn from the moon ; ascribing 

 the numerous pits either to the fall of planetesimals 

 or to volcanic action, there could scarcely fail to be 

 considerable traces of similar formations on the earth 

 unless the surface had been more or less molten. 

 The remaining arguments are geological rather than 

 astronomical, but one may be mentioned. The 

 amount of salt in the ocean has led to an estimate 

 of about 100.000,000 years for the period during which 

 rivers have been flowintj into it. This time-estimate 

 would be much too small if we accepted Chamberlin's 

 view of the early stage in the earth's history at which 

 the oceans appeared. 



