July 22, 1909] 



NATURE 



10: 



that the recently discovered retrograde satellites com- 

 plicate the centrifugal hypothesis is no serious argu- 

 ment against this hypothesis. They can be made to 

 fit into a general modified scheme. With regard to 

 the earth-moon system, the criticism based upon the 

 irregularity of present-day ocean tides seems irrelevant 

 to the main issue. In the past, at any rate, we must 

 look to regular body tides in the earth as the main 

 factor in tidal evolution; of these tides, as mathe- 

 matical analysis shows us, a natural result is a 

 retardation of rotation. There are several further 

 criticisms of interest in the paper, notably the reminder 

 that the moon, if brought down to the surface of the 

 earth (assumed to be of its present size), would be 

 inside the limit given by Roche's criterion of stability, 

 and would split into fragments. This point has 

 already been considered by Sir G. Darwin (N.ature, 

 18S6). In his discussion of it he abandons any idea 

 that his theory explains the actual method of genesis 

 of the moon, while he claims that it is of importance 

 in dealing with the moon's later history. 



The dynamical arguments of the paper are rein- j 

 forced by geological arguments. It is shown that 

 there is no geological evidence supporting the view 

 that in earlier times the earth's rotation was much 

 more rapid, and consequently the earth itself much 

 more oblate than at present. The greater part of the 

 changes must have taken place before the earth had 

 solidified and its surface had become a book for the 

 geologist to read. Only on such terms will the 

 geologist accept the tidal theory, and on this par- 

 ticular point he has the support of Kelvin. In view 

 of recent discoveries of unsuspected sources of heat 

 and energy, it seems that the necessary extension of 

 time involved in this requirement of the geologist 

 may be granted by the physicist, and that the theory 

 need not be abandoned by the mathematician at the 

 bidding of the geologist. 



Prof. Moulton's line of attack is quite distinct from 

 that of his colleague. By considerations of energy 

 and momenta alone he traces back the earth-moon 

 system under various simplifying assumptions to the 

 time when day and month were equal. He obtains 

 in all cases a distance between the centres of the two 

 bodies of more than 9000 miles. This result is very 

 much the same as that originally found by Sir G. 

 Darwin, but the latter suggested, without examining 

 the point very closely, that a consideration of the 

 sun's tidal effect would greatly diminish this distance. 

 Prof. Moulton proves that the actual difference due to 

 this cause is very slight, and his conclusion strongly 

 reinforces the view that fission must have taken place, 

 if at all, at a time when the earth was much less 

 dense than at present. The further contention that 

 the fission could not have been the result of increased 

 rotation alone has already been recognised as valid by 

 Sir G. Darwin. The latter's suggestion that the 

 coincidence of a solar tide with a free period of 

 oscillation of the earth might have led to a condition 

 of instability has been examined by Prof. Love (Phil. 

 Mag., March, 1S89), who showed the idea to be quite 

 feasible. 



Of the remaining papers in the volume, which deal 

 mainly with special points discussed by Chamberlin 

 or Moulton in relation to the wider problem, the 

 most interesting is an examination by Dr. Lunn of 

 the heat which would be developed in the building up 

 of a planet according to the planetesimal theory. A 

 general qualitative agreement with the known require- 

 ments of facts is reached. More could, perhaps, 

 hardlv be looked for. Perhaps the following general 

 criticism of the planetesimal theory may be made at its 

 present stage of development. In many respects it gives 

 a general qualitative agreement with observed facts, 



NO. 2073, VOL. 81] 



while its supporters are criticising older theories on 

 the ground that they lack at times a close quantitative 

 agreement with observed facts. It remains to be seen 

 whether the newer theory will come up to the standard 

 by which the older theories are being judged. 



F. Stratton. 



PROF. SIMON NEWCOMB. 



BY the death of Prof. Simon Newcomb science has 

 sustained one of the most severe blows of recent 

 years. America has lost her most eminent man of 

 science, and not since the death of Adams has the 

 world been deprived of so illustrious an investigator 

 in theoretical astronomy. Newcomb's career up to 

 1899 was described by Loewy in the article on 

 " Scientific Worthies " in Nature, vol. Ix., p. i, and 

 his activity and marvellous powers of work continued 

 up to the date of the illness that has just terminated 

 fatally. Since 1899 he has given us his interesting 

 book entitled " The Reminiscences of an Astronomer " 

 (1903), in which he described the early incidents 

 of his life and related the extraordinary circumstances 

 by which his steps were guided into the career which 

 led him to such eminence. 



Newcomb commenced his reminiscences with the 

 words : — " I date my birth into the world of sweet- 

 ness and light on one frosty morning in January, 

 1857, when I took my seat between two well-known 

 mathematicians (Winlock and Runkle) before a blaz- 

 ing fire in the office of the ' Nautical Almanac ' at 

 Cambridge, Mass." 



Though born at Wallace, in Nova Scotia, March 12, 

 1S35, Simon Newcomb was of almost pure New 

 England descent. His father was, he tells us, the 

 most rational and the most dispassionate of men, 

 who, when he had reached the age of twenty-five, 

 set forth to search for a wife who possessed the 

 qualities most suitable in a helpmeet. His search 

 had extended nearly a hundred miles before, in the 

 village of Moncton, he found in Emily Prince what 

 he desired, and his son says the marriage was " in 

 all respects a happy one, so far as congeniality of 

 nature and mutual regard could go." ..." My 

 mother was the most profoundly and sincerely re- 

 ligious woman with whom I was ever intimately 

 acquainted, and my father always entertained and 

 expressed the highest admiration for her mental gifts, 

 to which he attributed whatever talents his children 

 might have possessed. The unfitness of her environ- 

 ment to her constitution is the saddest memory of 

 my childhood. More I do not trust myself to say 

 to the public, nor will the reader expect more of me." 



How Newcomb's early years were passed may 

 perhaps be conjectured from the fact that the auto- 

 biographical chapter in which he records them bears 

 the title of " The World of Cold and Darkness." He 

 had, however, from his earliest years a keen desire 

 for knowledge, and read whatever books were avail- 

 able. His first introduction to the intellectual career 

 he desired was not promising. In those days there 

 was a so-called physician. Dr. Foshay, living near 

 Moncton, who was reputed to have effected cures 

 of sick persons given up by other doctors. As 

 Newcomb says, " Diomeds of the medical profes- 

 sion before whose shafts all forms of disease had 

 to fall were then very generally supposed to be 

 realities." By the intervention of an aunt, young 

 Newcomb agreed to live with the doctor, render- 

 ing him all assistance in preparing medicines, while 

 the doctor, on his part, undertook to supply New- 

 comb's bodily needs and teach him " the botanic system 

 of medicine." .'Vfter a little experience it began to dawn 

 upon Newcomb that Dr. Foshay, notwithstanding his 



