THE CONTROVERSY ON ACOUSTICAL RESEARCH. 483 



of his country. Such, if I dare say so, are the sentiments which I 

 have ever expressed regarding Prof. Henry here and elsewhere. 



When I first learned that he was in danger of falling into what I 

 considered to he grave scientific error, I went as far as friendliness 

 dared go to avert it. I addressed to him a private letter, in which I 

 tried to impress upon him the completeness and conclusiveness of the 

 evidence which he seemed disposed to call in question. He did not 

 honor that letter with any notice, preferring to discuss the subject 

 publicly in the " Report of the Washington Lighthouse Board." He 

 was clearly within his right in doing so ; but I submit that I only 

 exercised my right when I met him on ground thus chosen by 

 himself. 



No English gentleman that I have consulted can discern in what 

 I have written any violation of the dignity of scientific debate ; but 

 your article would lead to the inference that I had both violated com- 

 mon honesty and taken leave of common-sense. I will not quote your 

 words, because I cherish the hope that when you have reflected on 

 them you will regret them. When I say "you," I mean the editor of 

 the Nation^ whose acquaintance I had the honor to make, and whose 

 kindness I had the privilege to experience, in New York I do not 

 mean the writer of the article. Let me respectfully assure you, then, 

 that, Avhen I spoke of being " deflected by authority," " Prof. 

 Henry's solution of ocean-echoes " was not at all in my mind, nor his 

 " ruin," partial or total, in my calculations. Consider, I pray you, how 

 impossible it is that this could have been the case. The " deflection" 

 spoken of is expressly described as occurring at the outset of an inves- 

 tigation begun in May, 1873, whereas the Washington report contain- 

 ing Prof. Henry'' s solution of ocean-echoes is the report for 1874, 

 which did not reach Europe until the spring of 1875. This, then, is 

 the crumbling foundation on which your critic builds his odious 

 charge. In verity, the remark on which he pours his peroratory 

 invective w'as not meant for " laudation " of any kind, but merely to 

 show the "polar" character of authority its good side and its bad. 



It is easy, as you know, Mr. Editor, to sneer and to assail ; but 

 less easy to show, without going into details not worth the labor, that 

 the sneer is unmeaning, and the assault unfair. Nevertheless, the 

 broad lines on which, in the present instance, I would meet my anony- 

 mous assailant may, I think, be made clear. He industriously mixes 

 together things which ought to be kept apart experiments on fog- 

 signals and inquiries into " the causes which afliect the transmission 

 of sound through the atmosphere." The " blank " which I proposed 

 to fill is stated, with unmistakable clearness, to have reference solely 

 to such " causes." Neither Herschel nor Robinson, as far as I know, 

 ever made an experiment on fog-signals ; still I quote them. Why ? 

 Because they are the most eminent and authoritative exponents of 

 the theories of acoustic opacity which up to last year were entertained 



