26 m Prof. TyndalPs Notes on Scientific History. 



2. Mayer was led from the contemplation of organic nature to 

 the publication of his first paper (< On the Forces of Inorganic 

 Nature." An observation made in 1840, on the blood of a 

 patient in a tropical climate, was the origin of his scientific 

 writings. It led him to the consideration of those physical 

 forces on which the phenomena of vitality depend. This, if the 

 laws of life were ever to become amenable to scientific investi- 

 gation, he knew must be his starting-point. The paper now 

 under consideration may be broadly divided into two parts, in 

 the first of which he deals with the law of the conservation of 

 energy* as it manifests itself in inorganic nature, and in the 

 second of which he applies the law to the phenomena of life. 



3. At the outset of this paper he announces, as he had pre- 

 viously done in that of 1842, the indestructibility of force, its 

 convertibility, and its quantitative constancy. Chemistry, he 

 says, teaches the qualitative changes which matter undergoes 

 under different circumstances, the form of the matter and not 

 its amount being changed. What chemistry does for matter, 

 physics must do for force; the force is as unalterable as the 

 matter, and the function of physics is to study force in its forms, 

 and to ascertain the conditions of its metamorphoses. This is 

 the sole problem with which natural philosophy has any concern ; 

 for as to the creation or annihilation of force, either act lies as 

 much beyond the range of human thought as of human power. 



4. For thousands of years men have employed the powers of 

 inorganic nature to obtain mechanical effects. But to the forces 

 of moving air and of falling water a new force has been added 

 in modern times — the force of heat, which may be converted 

 into mechanical effect. Supposing that to a train weighing 

 100,000 lbs. a velocity of 30 feet a second is to be imparted; 

 this may be done by the expenditure of ordinary mechanical 

 force — by permitting, for example, the train to roil down an 

 incline until the required velocity has been obtained. Trains, 

 however, in general move without this exercise of gravitating 

 force, and, despite the friction of their parts, they are kept in 

 motion. Let this friction be supposed equivalent to a rise of 1 

 in 150, then with a velocity of 30 feet a second the weight of 

 the train will be lifted 720 feet in an hour, which corresponds 

 to the work of about forty-five horses. This large quantity of ge- 

 nerated motion implies the expenditure of an equal amount of 

 force. The force expended in the case of the locomotive is heat. 



The quantity of heat taken up by the steam employed to 

 work the engine is greater than that which can be obtained from 

 the recondensation of the steam. The difference between both 



* Rankine's terminology. 



