8o SECTION PHYSICS. 



The CHAIRMAN : I now ask you to pass a very hearty vote of 

 thanks to Mr. Hamilton for his very successful research, and for the 

 extremely lucid way in which he has brought it before us. 



The Conference then adjourned until two o'clock. 



On reassembling, Mr. DE LA RUE, D.C.L., F.R.S., took the chair. 



He said : There has been a slight change in the programme this 

 afternoon in consequence of the modesty of M. Tresca, which prevents 

 him speaking twice on the same subject. He has already brought 

 before the Conference his wonderful researches "on the Fluidity of 

 Solids/' and he desires, being present this afternoon, and being 

 connected with the " Conservatoire des Arts et Metiers " in Paris, to 

 speak of the historical monuments of science and on the institutions 

 which ought to preserve them. 



UPON OBJECTS ILLUSTRATING THE HISTORY OF SCIENCE, AND 

 THE MEANS OF ENSURING THEIR CONSERVATION. 



M. TRESCA : Gentlemen, Mr. Spottiswoode informed me yesterday 

 that he had put my name down for a conference upon the Fluidity of 

 Solids. It would have been impossible for me to comply with his 

 wishes, since I have already touched upon that subject on Wednesday 

 last ; and, consequently, I can only show you my good will by offering 

 you another subject for discussion. I will accordingly replace a 

 question, which, on repetition, might be considered too personal, by a 

 few observations on the most advisable means of preserving the 

 historical apparatus collected in your exhibition, but which are yet far 

 from sufficient in number to satisfy, as fully as might be wished, our 

 scientific curiosity. In England, Newton's telescope, Newcomen's and 

 Watt's steam-engines ; in Italy the apparatus of Galileo, of Torricelli, 

 of Volta, of the Academy del Cimento; in Holland, the instruments by 

 which Huyghens made his discoveries, and the apparatus of 

 s'Gravesande and of Otto von Guericke, certainly form precious collec- 

 tions, but how many other important discoveries would not have been 

 likewise represented, if as much care had been bestowed upon 

 preserving the instruments, as in publishing their results. Without 



