THE CONTROVERSY ON ACOUSTICAL RESEARCH, 485 



ly says was lent "gratuitously" to me^ was paid for in February, 

 1874, and two others are at this moment on their way from New York 

 to England. Both by word and deed have we acknowledged our real 

 obligations to the United States ; but what we did not and could not 

 acknowledge (for it was non-existent) was, any solution of the conflict- 

 ing and anomalous results obtained with these fog-signals results so 

 conflicting and so anomalous as to cause reflecting minds to entertain 

 doubts as to the capacity of the observers. Apart from the friend- 

 ship shown to me at the time, all that I remember of the meeting at 

 Washington, to which your critic refers, is the utter perplexity of 

 everybody present, myself included, in regard to the matter in hand. 

 I had my guess others had theirs ; but we were quite at sea in our 

 guesses, without a signal to guide us through the intellectual fog. 



Knowing, indeed, the difliculty of the subject, when its investiga- 

 tion was first proposed to me by the Elder Brethren, I shrank (as 

 Faraday had done before me) from a work of such obvious labor and 

 such uncertain scientitic promise. Doggedly, however, we attacked 

 it, determined to go through the mechanical processes already fol- 

 lowed by others, even if they led, as regards science, to an equally 

 barren result. Out of the darkness at length came the dawn. We 

 prolonged our investigations until they embraced every agent, save 

 one, to which influence had been previously ascribed. The exception 

 was snow. This, however, was directly met by observations made 

 upon the Mer de Glace in the bitter winter of 1859, and which have 

 been entirely confirmed by the later observations of General Duane. 

 Having negatived antecedent theories, we wrought our way positively 

 to the basis of the whole question. This we found in a cloud-world, 

 invisible to the eye of sense, but as visible and certain to the mental 

 eye as the ordinary cloud-world of our atmosphere. The lights and 

 shadows of these " acoustic clouds " the action of which must, at one 

 time or another, have been noticed by every peasant within range of 

 a peal of bells sufiiced to account for the most astounding variations 

 of intensity. This, I say, has been established, not only by patient 

 and long-continued observations afloat, but by laboratory experiments 

 as indubitable as any within the range of physical science. 



And, let me add, it was neither whistles nor trumpets, nor yet the 

 siren, which pointed out the way to this solution, but experiments 

 with guns ably served by artillerymen from Dover Castle. 



I will not make any further draft upon your generosity, though, 

 were it worth while to do so, other fallacies of fact and logic in your 

 critic's article miglit be exposed. He says, or intimates, for example, 

 that I became " adviser " to the Trinity House after my " lecturing 

 tour in the United States in 1873." I relieved Michael Faraday of 

 this duty in May, 1866. My friends in New York have already had 



^ It was lent to the Trinity House Corporation ; and I expressly signalize the lending 

 aa "an act of international courtesy worthy of imitation." 



