340 



SCIENCE 



[N. S. Vol. XXX. No. 767 



direction of motion of the satellite nucleus that 

 in this case its motion around M will be acceler- 

 ated by its collision with m. . . . The effect of the 

 accelerations by the scattered material is to en- 

 large the orbit of the satellite nucleus, and to 

 prevent its being drawn down upon the growing 

 planetary nucleus. 



Now the speeds of the larger planets and of 

 their satellites are as follows : 



On the very face of the table it will be seen 

 that six satellites contradict the book. When 

 we get into it deeper we find they all do. Thus 

 if we suppose the colliding particles to be 

 equally distributed in space we have for those 

 within the planet's orbit : 







for their mean velocity at the point of col- 

 lision ; a being the semi-major axis of any par- 

 ticle. 



This equals 0.Y9 of the planet's orbital speed. 

 A result substantially similar is got for any 

 other possible distribution. 



From this it appears that all the large satel- 

 lites of all the large planets have spatial 

 speeds which would cause them to be retarded 

 by such impacts or exactly the opposite of 



what the book states. So that the supposed 

 proof by this of the planetesimal hypothesis 

 turns out to be a disproof of it. 



From what we have said it will be seen that 

 the hypothesis expounded will not work. 



Percival Lowell 



the nomenclature question 

 To THE Editor of Science: May I add a 

 few words to the excellent letters by Mr. F. 

 N. Balch' and Dr. W. H. DaUf 



It is necessary first to assume that zoolo- 

 gists in general accept or wish to accept the 

 rules drawn up by the Nomenclature Com- 

 mittee of the International Zoological Con- 

 gress. The assumption may be a ridiculous 

 one, but it will at any rate be admitted that 

 until those rules are generally accepted fur- 

 ther discussion is premature. 



I agree with Dr. Dall that most cases can 

 be settled by a rigid application of the code. 

 There are a few in which the interpretation 

 or application of the code may be obscure. 

 These must be remedied either by greater 

 precision in the rules or by the decisions of a 

 court in the manner described by Mr. Balch. 

 There are other cases in which the conse- 

 quences of the rules are perfectly clear, but 

 at the same time exceedingly unfortunate — so 

 unfortunate indeed are some of them that a 

 great many zoologists are beginning to say 

 " So much the worse for the rules."^ A phrase 

 has often been used that we should accept the 

 principle of priority " tempered with common 

 sense." This would be all very well if there 

 were such a thing as common sense, but it is 

 notorious that in these matters quot homines, 

 tot sententicB. In a recent paper' I have 

 therefore ventured to repeat an old proposal, 

 for which the time now seems to be more ripe, 

 and as that paper may not be very widely seen, 

 I ask you to print the following extracts : 



' Science, June 25, pp. 998-1000. 



' Science, July 30, pp. 147-149. 



^ See, for instance, a letter to Nature for August 

 27, 1908, pp. 394-395, signed by many leading 

 British zoologists. 



' " Some Common Crinoid Names, and the Fixa- 

 tion of Nomenclature," Ann. Mag. Nat. Hist. (8), 

 IV., pp. 37-42, July, 1909. 



