Urgent necessity Jor new knowledge. 69 



leakage of gas ; iron smelters wish to avoid the evil 

 effects of impurities in the iron; manufacturers in gen- 

 eral want to utilise their waste products and prevent 

 their polluting our streams an-i atmosphere ; and so 

 on without end. And inventors are continually trying 

 to supply these demands, by exercising their skill in 

 every possible way, with the aid of scientific informa- 

 tion contained in books ; but after putting manufac- 

 turers and themselves to great expense, they very 

 frequently fail, not always through want of inventive 

 skill, but often through want of new knowledge attain- 

 able only by means of pure research. Judging from 

 the vast amount of inventive skill already expended 

 upon the steam engine, and the small proportion of 

 available mechanical power yet obtained from the 

 coals consumed in it, it is highly probable that a 

 machine for completely converting heat into mechan- 

 ical force cannot be invented until more scientific 

 knowledge is discovered. 



It must not be supposed from these remarks, that 

 discoveries which will enable a man to make any 

 particular invention, can be produced to order ; that 

 is only true to a very limited extent. Men are beggars 

 of nature, and must not expect to be permitted to 

 choose her gifts, or dictate what secrets shall be dis- 

 closed. We may however be certain that if we acquire 

 a very much greater supply of new scientific know- 

 ledge, we shall then be able to perfect many good 

 inventions, though not always of the kind we wish, or 

 in the way we expect. The great sewage question 



