No. XIILJ APPENDIX. 217 



of the exertion of a power will amply suffice for my purpose ; I can 

 employ light to give rise to certain actions. On the table before you lie 

 daguerreotypes, calotypes, cyanotypes, chrysotees, enargyotypes, photo- 

 graphs, produced by the action of light. Man alone can use light, and in 

 the instances before you it even required such men as Daguerre, Herschel, 

 Fox Talbot, and Hunt, to turn the force to account. (Applause.) We all 

 of us use heat ; in fact, no meal is prepared without its agency. From 

 the manufacture of the homely bread to the preparation of the most costly 

 viands, this force is equally requisite for man ; and yet what animal can 

 or does employ this force of matter ? I will show you a somewhat 

 mysterious application of heat, if you will please observe the head of the 

 worthy god which was placed by the builder in this theatre for orna- 

 ment. You will perceive that an explosion will occur. The explanation 

 of this explosion is simple a wire was previous to the lecture placed 

 around this theatre, and when I requested your attention to the image I 

 completed a galvanic circuit, and the force generated in this battery was 

 transmitted through the wires, and produced heat where I wanted it, 

 namely, at the top of that figure. There, before lecture, I had placed some 

 gunpowder, which exploded on the application of the heat. 



Nor are these forces alone obedient to the power of man. I will 

 show you how we can use the power of electricity; I will connect this 

 electro-magnetic machine with the battery, and you will see the result. 

 The rapidity with which it turns is enormous, and it affords a prac- 

 tical application of the power of man to use electricity. You can 

 hardly view that beautiful bas-relief without admiring the sculptor's 

 design ; but when I tell you that specimen, the largest yet executed, was 

 deposited, atom by atom, by means of the galvanic force, you will admit 

 the power of man to use electricity. Other examples are on the table ; 

 those beautiful solid electro-silver and electro-silver-gilt waiters, made 

 from the natural vine-leaf, show the power of man to employ this force. 



We daily use ordinary force. The model of the locomotive engine on 

 the table is brought here to impress that fact on your mind ; but, as you 

 must all be practically conversant with railway engines, I have not 

 thought it necessary to set the model in action. 



Man can also employ the force of sound, of which a musical snuff- 

 box is an instance ; but perhaps the use of the porter's bell, to signify 

 the commencement of this lecture, suffices for an illustration of man's 

 power to employ this force. 



I have thus demonstrated that man can employ attraction, heat, light, 

 electricity, force, and sound, to act upon matter ; but, doubtless, you will 

 tell me the electric eel kills his prey by electricity, the glow-worm lights 

 its lamp, animals in their own bodies generate heat, and the merry cricket 

 gives rise to cheerful notes. All these creatures, however, only employ 

 the forces which arise from peculiar structures in their bodies man gives 

 rise to these forces. The electric eel uses the electricity generated in the 

 organ, which I now exhibit to you, called the battery; the glow- worm 

 furnishes light by the peculiar organization of the last two segments of 

 the body. Man, however, makes the battery man makes the candle, 

 so that man causes matter to produce light, heat, and the various other 

 forces which I have enumerated a power which no animal possesses. 

 (Applause.) 



