870 



SCIENCE 



[N. S. Vol. XXV. No. 648 



GEEENWICH CLOCK 



Mean Meau 



Daily Bate Deviation 



1905 s. 3. 



Feb. 1-4 — .243 .016 



6-12 .225 .002 



12-21 .225 .002 



21-Marcli 1 .258 .031 



March 2-12 .228 .001 



12-18 .220 .007 



18-24 .200 .027 



24-Apr. 1 .217 .010 



April 1- 8 .222 .005 



8-16 .222 .005 



16-23 .178 .049 



23-May 1 .232 .005 



May 1- 6 .248 .021 



6-12 — .274 .047 



Mean — .227 ± .018 



Range 0».096. 



Thomas Lewis 

 Time Depaktment, 

 RoTAL Obseevatoet, Geeenwich 



REASONS FOR BELIEVING IN AN ETHER 



Several weeks ago an article with this title 

 appeared in Science. In it were mentioned 

 two reasons for the belief in an ether; but 

 what seems to me the most powerful of all 

 arguments was not mentioned, nor is it often 

 referred to elsewhere. It is alluded to by 

 Maxwell in his article ' Ether," where we find 

 these words : 



In the next place, this energy is not transmitted 

 instantaneously from the radiating body to the 

 absorbing body, but exists for a time in the me- 

 dium. 



The ether was originally invented to avoid 

 the assumption of action at a distance; but 

 there are no insuperable objections to action 

 at a distance provided it he instantaneous. 

 Herein lies the point of the argument. We 

 have replaced the old question : " Can a body 

 act where it is not ? " by the far more search- 

 ing question: "Can a body act when it is 

 not ? " 



The energy sent out by the sun, for in- 

 stance, reaches the earth after a lapse of some 

 eight minutes. What of the energy during 



'Eneyc. Brit., ninth edition, Vol. VIII., p. 570. 



that time? The principle of the conservation 

 of energy forbids our supposing that it is an- 

 nihilated and recreated eight minutes later; 

 and it will hardly be urged, I think, that it 

 exists as a sort of disembodied spirit during 

 that interval. There must be some medium 

 in which it may reside during its finite time 

 of passage from place to place. 



The ether stands or falls with the principle 

 of the conservation of energy. 



Paul E. Heyl 



the FIRST SPECIES RULE 



The article by Professor John B. Smith in 

 the May 10 number of Science under the 

 above title, in which exception is taken to 

 the operation of the first species rule in the 

 case of the lepidopterous genus Bhynchagrotis 

 Smith, can hardly be considered as an argu- 

 ment against the use of this method of type 

 fixing. His objection is against the selection 

 of a doubtfully referred species as the type of 

 a genus, a matter which is fully covered in 

 most, if not all, codes and is entirely inde- 

 pendent of the method of selecting types, 

 whether by elimination or first species rule. 



In the specific case mentioned by Professor 

 Smith we fail to see that the species chardinyi 

 selected as the type by Sir George Hampson 

 was ' questionably referred,' as in the original 

 description Professor Smith says : " The group, 

 though placed with, and certainly very closely 

 allied to cupida, yet shows so many peculiar 

 characteristics that' it would seem possible to 

 separate it by a distinct generic term. The 

 two species rufipectus and hrunneicollis are, 

 however, somewhat intermediate and as the 

 species (chardinyi) can hardly be referred to 

 Triphwna, I prefer to leave it here." Eegard- 

 ing this Professor Smith states in his recent 

 article : " my reason for placing it there being 

 that I believed it would prove to be properly 

 referable to an exotic genus to which I did 

 not care to risk making a synonym." 



James A. G. Eehn 

 Academy of Natural Sciences, 

 Philadelphia, Pa., 

 May 17, 1907 



