656 THE POPULAR SCIENCE MONTHLY. 



genesis, but threw important light on the conditions which must be 

 fulfilled in order to secure complete sterility. But original research is 

 not the only way in which a man can advance the cause of science. 

 All-important though it is, it nevertheless often happens that an origi- 

 nal investigation is too abstruse to be followed by more than a few 

 experts ; nor is it by any means necessarily the case that an eminent 

 investigator is equally successful in expounding to others, especially 

 to a mixed audience, the results at which he himself or other investi- 

 gators may have arrived. The general diffusion of science depends 

 largely on the clearness with which its leading principles and results 

 are expounded, whether by lectures or by treatises, in which, while 

 they are scientifically sound, popularity of style and general readable- 

 ness are not sacrificed to the dry exactness of scientific detail. Most 

 of us have had opportunities, whether at the Royal Institution, with 

 which the name of Tyndall has so long been connected, or elsewhere, 

 of being impressed with the singularly lucid style and graphic expres- 

 sion with which he expounded to his audience the salient points of the 

 scientific subject which he brought before them. Nor was it only in 

 clearness of verbal exposition that he excelled ; the manipulative skill 

 with which his original investigations were carried on served him in 

 good stead in his more popular expositions ; and by the aid of that 

 " domestic sun," which even the murky atmosphere of a London win- 

 ter could not obscure, he was enabled in very many cases to exhibit 

 to the audience the actual results of experiments which had first been 

 carried out in the quiet of the laboratory. Nor is it our own country- 

 men alone who have had the benefit of Dr. Tyndall's lucidity of ex- 

 position. Our friends across the ocean have flocked to hear and have 

 appreciated the lectures which ho has there delivered as a free gift to 

 transatlantic science. But oral lectures, after all the lectures at least 

 of one individual can only reach a fraction of the community ; nor 

 do they admit of that pause for thought which the learner requires in 

 endeavoring to make himself master of a new subject. But the same 

 qualities of mind which enable a man to be a clear and interesting lect- 

 urer fit him also to be the author of eminently readable books ; and 

 for the general diffusion of science which is taking place we owe much 

 to the writings of Dr. Tyndall. 



TROFESSOR TYNDALL's SPEECH. 



Mr. President, my Lords, and Gentlemen : "When the project 

 of a dinner was first mentioned to me by a very old and steadfast 

 friend of mine, who, to my regret and his, is not here to-night, had 

 any dream, or vision, of the assembly now before me risen on my 

 mind's eye, I should have declined the risk of standing in my present 

 position ; for I should have doubted, as I still continue to doubt, my 

 ability to rise to the level of the occasion. Gratitude, however, is 

 possible to all men ; and I would offer you, sir, my grateful thanks for 



