THE CONTROVERSY ON ACOUSTICAL RESEARCH. 477 

 THE CONTROYEKSY ON ACOUSTICAL EESEARCH. 



TYNDALL ON SOUND.' 



THE work of Prof. Tyndall on the philosophy of sound has won 

 for itself, in its former editions, the highest possible recognition 

 among scientific men, not only in England, but in other countries. A 

 little more than a year ago, the second edition of this book was trans- 

 lated into German under the special supervision of such eminent in- 

 vestigators as Helmholtz and Wiedemann. In the work before us we 

 have the third revision of the eminent professor's observations under 

 this head. In preparing it, he says, he has subjected the previous edi- 

 tion to a careful reexamination, and, in so doing, has " amended as far 

 as possible its defects of style and matter, and paid at the same time 

 respectful attention to the criticisms and suggestions which the former 

 editions called forth." 



In the preface to this publication it is announced by Prof. Tyndall 

 that the new matter of greatest importance which has been introduced 

 into it is an account of an investigation which during the past two 

 years he has been conducting in connection with the Elder Brethren 

 of the Trinity House. It may not be known to all our readers that 

 what we call our Lighthouse Board at Washington is known in Eng- 

 land as " The Trinity House." The title carries us back to the era 

 when monasticism was prevalent in Europe. In its original charter, 

 the body was named "The Masters, Wardens, and Assistants of the 

 Guild, Fraternity, or Brotherhood of the most Glorious and Undivided 

 Trinity, and of St. Clement, in the Parish of Deptford Stroud, in the 

 County of Kent." In the year 1836, an act of Parliament vested in 

 this " Trinity House," as then constituted, the entire control of the 

 lighthouses of England and Wales, and gave it certain powers over 

 the lights in Scotland and Ireland. Prof. Tyndall appears to have 

 entered on his duties as " the scientific adviser " of the Elder Brethren 

 shortly after his return to England at the close of his lecturing tour in 

 the United States in the year 1873. In the seventh chapter of the 

 present volume, under the head of " Researches on the Acoustic Trans- 

 parency of the Atmosphere in Relation to the Question of Fog-Signal- 

 ing," he gives the processes and the results of some very interesting 

 observations which he has conducted under the patronage of the Brit- 

 ish Trinity House. The general results of these observations had 

 already transpired, but in the work before us they have received the 

 professor's definite statement side by side with a narrative of the re- 

 searches fi-om which they liave been deduced. It is to this portion of 

 the volume, containing " the new matter of greatest importance," that 

 we propose to confine our attention in this shoi't review. 



' From the Nation of October 28, 1875. 



