THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



MAY 1841. 



LIV. Remarks on Professor Challis's Reply to Mr. Airy's Ob- 

 jections to the Investigation of the Resistance of the Atmo- 

 sphere to an Oscillating Sphere. By George Biddell 

 Airy, Esq., M.A., F.R.S., Astronomer Royal. 



To the Editors of the Philosophical Magazijie and Journal. 

 Gentlemen, 



T HAVE not had leisure earlier to notice the remarks of 

 ■*• Professor Challis in your February Number, upon my ob- 

 jection to his investigation of the resistance to a spherical 

 body oscillating in an elastic medium. I beg to express my 

 sense of the courtesy with which Professor Challis has replied 

 to my objection, and to avow my opinion that a discussion 

 conducted in this manner cannot but be advantageous to the 

 interests of science. With this feeling, I think it right again 

 to state that the considerations urged by Professor Challis in 

 his last communication, do not at all remove my objection to 

 the fundamental parts of his investigation. And I trust that, 

 by putting my own reasoning in a different form, I shall be 

 able to show, to the satisfaction of Professor Challis, that the 

 solution which he has adopted for expressing the movement 

 of the particles of air surrounding the ball, is untenable. 



The reasoning of a mixed nature upon which Professor 

 Challis has founded and supported his investigation, and 

 upon which also I have objected to it, is (if I may use such a 

 term) extremely hazardous. I mean by tliis expi'ession to as- 

 sert, that, unless managed with the greatest caution, it is apt 

 to introduce or to conceal important errors of principle. I 

 shall, therefore, abandon this kind of reasoning, and shall 



Phil. Mag. S. 3. Vol. 18. No. 118. Maj 1811. Y 



