5 04 THE POPULAR SCIENCE MONTHLY. 



everything, down to the minutest detail, was prepared with nicety ; and the ex- 

 periments were consequently performed with a precision uuequaled by the manip- 

 ulation of an accomplished conjurer. 



The qualities which characterized his lectures were reflected, as far as pos- 

 sible, in his writings. There was the same clearness of thought, the same vigor of 

 expression. Most of his writings were, indeed, reproductions or developments 

 of his lectures ; witness his popular works on Sound, Light, and The Forms of 

 Water. His best-known book, Heat considered as a Mode of Motion in which 

 he presented, thirty years ago, an admirable exposition of the phenomena of heat 

 in accordance with the dynamical theory may be accepted as typical of his 

 felicity of expression and readiness of illustration. 



It was these rare gifts as an interpreter of science which first 

 drew the attention of American readers to Prof. Tyndall, and 

 which finally led to his visit to this country in~1872. Many now 

 living will recall that event and the impulse given to American 

 science by the brilliant course of lectures which he delivered in 

 our chief Atlantic cities. 



Having been asked to prepare a brief account of this visit, and 

 being assured that it will be of interest just now to the readers of 

 the Monthly, I have decided to comply with the request. I am 

 enabled to do this by the aid of documents and letters left by my 

 lamented brother, E. L. Youmans, who for many years enjoyed 

 the friendship of Prof. Tyndall, and was in frequent correspond- 

 ence with him. 



Tyndall's first book, The Glaciers of the Alps, was brought out 

 here by Ticknor and Fields in 1861. All who read it were fasci- 

 nated by the clearness and beauty of its style and the ease with 

 which its facts and principles could be understood. 



The year following, my brother made his first visit to England, 

 and while in London it was his good fortune to be introduced to 

 Tyndall. In a letter of September 25th he writes : 



I went with Spencer at his request to see Tyndall respecting the publication 

 of his forthcoming book. He was at the Royal Institution, where his researches 

 are carried on in a dingy hole down cellar, which Tyndall denominated " the 

 den." He is a single man of forty, with a scanty strip of forehead, and big, 

 straight, prominent nose the most restless, nervous creature I ever set eyes on^ 

 We stayed but a few minutes, and nothing was said of anything but the book, and 

 the publication of books. 



The work here referred to was Heat as a Mode of Motion, at 

 that time in the hands of the printers in London. 



Another letter written from Cambridge during the same visit,, 

 when he was attending the meeting of the British Association, 

 describes Tyndall's manner as a lecturer : 



Last night there was an address by Tyndall before the association in the 

 lecture room ; subject, water in its several conditions. It was altogether the 

 most brilliant affair of the kind I have ever seen. The new philosophy of forces- 



