u 



But it is the almost necessary result of scientific discoveries to lead 

 on to others, and also to give unity and simplicity and consistency to 

 the knowledge already attained : and I wish to call your attention to 

 certain steps which have lately been made, both because they are re- 

 markable in themselves, and because they help towards the general 

 conclusion to which I wish to conduct your minds. 



The first great step which I will mention is that which is expressed 

 by the terms Conservation and Transformation of Energy. I am here 

 using technical terms, and I am not sure whether it is possible to convey 

 to minds which have had no scientific training precisely what is intended 

 by the terms ; but perhaps something may be done, and, at all events, it 

 is worth while to try. Of course I might refer you to the Lectures, of 

 which I have already said that I should make use ; but I wish rather, 

 if I can, to put the matter in a still simpler form, and to make it to 

 some extent intelligible to persons who would not be capable of reading 

 these Lectures, and similar scientific treatises, with much advantage or 

 satisfaction. 



Let us begin, then, with a much simpler example of Conservation 

 and Transformation than that of Energy, namely, the Conservation and 

 Transformation of Matter. It is, I suppose, a familiar thought with 

 most of us, that matter cannot be destroyed. We commonly speak of 

 destraction, but there is no such thing in nature. You burn a piece of 

 wood, or a piece of coal, and the result is to resolve the wood or coal 

 into its constituent parts, but those constituent parts are simply separated 

 from each other, or compelled to combine with other substances ; 

 destroyed they never are. There is a story, I know not whether 

 authentic or imaginary, of Sir Walter Raleigh, when smoking in the 

 presence of Queen Elizabeth and her Court ladies a piece of the newly- 

 introduced article tobacco, amusing the royal party by offering to weigh 

 the smoke, the production of which was being watched with so much 

 interest. The Court ladies laughed at the promise ; but when the pipe 

 was smoked out. Sir Walter calmly knocked out the ashes, and pointed 

 out that if they were weighed, and the weight subtracted from that of 

 the tobacco, as originally deposited in the pipe, the remainder would 



