138 ON THE INTERACTION OF NATURAL FORCES. 



elusion of the piece bowed courteously to the audience. That 

 men like those mentioned, whose talent might bear comparison 

 with the most inventive heads of the present age, should spend 

 so much time in the construction of these figures, which we 

 at present regard as the merest trifles, would be incompre- 

 hensible if they had not hoped in solemn earnest to solve a 

 great problem. The writing-boy of the elder Droz was publicly 

 exhibited in Germany some years ago. Its wheelwork is so 

 complicated that no ordinary head would be sufficient to de- 

 cipher its manner of action. When, however, we are informed 

 that this boy and its constructor, being suspected of the black 

 art, lay for a time in the Spanish Inquisition, and with diffi- 

 culty obtained their freedom, we may infer that in those days 

 even such a toy appeared great enough to excite doubts as to its 

 natural origin. And though these artists may not have hoped 

 to breathe into the creature of their ingenuity a soul gifted with 

 moral completeness, still there were many who would be willing 

 to dispense with the moral qualities of their servants, if at the 

 same time their immoral qualities could also be got rid of; and 

 to accept, instead of the mutability of flesh and bones, services 

 which should combine the regularity of a machine with the 

 durability of brass and steel. 



The object, therefore, which the inventive genius of the 

 past century placed before it with the fullest earnestness, and 

 not as a piece of amusement merely, was boldly chosen, and 

 was followed up with an expenditure of sagacity which has 

 contributed not a little to enrich the mechanical experience 

 which a later time knew how to take advantage of. We no 

 longer seek to build machines which shall fulfil the thousand 

 services required of one man, but desire, on the contrary, that 

 a machine shall perform one service, and shall occupy in doing 

 it the place of a thousand men. 



From these efforts to imitate living creatures, another idea, 

 also by a misunderstanding, seems to have developed itself, and 

 which, as it were, formed the new philosopher's stone of the 

 seventeenth and eighteenth centuries. It was now the en- 

 deavour to construct a perpetual motion. Under this term was 



