2^2 CLASSICS OF MODERN SCIENCE 

 ing. The axes of our carriages must be protected, by careful greas- 

 ing, from ignition through friction. Even lately this property has 

 been applied on a large scale. In some factories, where a surplus of 

 water power is at hand, this surplus is applied to cause a strong iron 

 plate to rotate swiftly upon another, so that they become strongly 

 heated by friction. The heat so obtained warms the room, and thus a 

 stove without fuel is provided. Now, could not the heat generated by 

 the plates be applied to a small steam engine, which in its turn should 

 be able to keep the rubbing plates in motion? The perpetual motion 

 would thus be at length found. This question might be asked, and 

 could not be decided by the older mathematico-mechanical investiga- 

 tions. I will remark, beforehand, that the general law which I will 

 lay before you answers the question in the negative. 



By a similar plan, however, a speculative American set some time 

 ago the industrial world of Europe in excitement. The magneto- 

 electric machines often made use of in the case of rheumatic disorders 

 are well known to the public. By imparting a swift rotation to the 

 magnet of such a machine, we obtain powerful currents of electricity. 

 If those be conducted through water, the latter will be reduced into its 

 two components, oxygen and hydrogen. By the combustion of hydro- 

 gen, water is again generated. If this combustion takes place, not in 

 atmospheric air, of which oxygen only constitutes a fifth part, but in 

 pure oxygen, and if a bit of chalk be placed in the flame, the chalk will 

 be raised to a white heat, and give us the sun-like Drummond's light. 

 At the same time, the flame develops a considerable quantity of heat. 

 Our American proposed to utilize in this way the gases obtained from 

 electrolytic decomposition, and asserted that by the combustion a 

 sufficient amount of heat was generated to keep a small steam engine 

 in action, which again drove his magneto-electric machine, decomposed 

 the water, and thus continually prepared its own fuel. This would 

 certainly have been the most splendid of all discoveries ; a perpetual 

 motion which, besides the force which kept it going, generated light 

 like the sun, and warmed all around it. The matter was by no means 

 badly cogitated. Each practical step in the afifair was known to be 

 possible ; but those who at that time were acquainted with the physical 

 investigations which bear upon this subject could have affirmed, on 

 first hearing the report, that the matter was to be numbered among 



