146 ANNUAL OF SCIENTIFIC DISCOVERY. 



power is, in every case, in proportion to the quantity of heat lost ; 

 or rather, this heat is transformed into mechanical labor ; it reappears 

 so soon as the labor is employed, in the quantity of water beaten up 

 by the steamship's paddles, &c., &c. According to Carnot, when the 

 temperature fell, this " fall " was accompanied with the production of 

 a certain amount of labor. In the new theory, the dilation of bodies 

 by the penetration of heat, changes the nature of a part of the bodies, 

 and the deficit which results therefrom is in proportion to the resist- 

 ance to be overcome during the accomplishment of this dilation. The 

 heat disappears, but a disposable labor is produced, and science con- 

 quers a new idea that a weight raised to a certain height is the 

 equivalent of a certain amount of heat. 



M. V. Regnault, (the best experimenter in France,) is fast demol- 

 ishing Carnot's theory by irresistable facts gathered in his laboratory. 

 " The heat of the boiler," said Carnot, " must be found integrally on 

 its egress from the cylinder." But according to the most precise 

 measures, M. Regnault found that in a very close machine, (without 

 condensation) into which steam penetrated 5 atmospheres, and left 

 it under ordinary pressure, the quantity of heat possessed by the 

 steam on its entrance, was about 653 unities, and at its egress about 

 637. In a machine with a condenser, the difference is still greater, 

 the figure 637 is reduced to 619. There are 16 unities lost in the first, 

 and 34 in the second case. In other terms, there is 1-40 or 1-20 part 

 of the total heat transformed into available labor, which explains, by 

 the way, clearly enough, the economical value of machines with con- 

 densers. It was also pretended that the quantities of heat disengaged 

 or absorbed by the same elastic fluid, were equal when the fluid passed 

 from the same initial state to a final identical state, whatever might be 

 the sense in which the transition was made ; in other words, it was 

 admitted that these quantities of heat depended only on the initial and 

 final conditions of temperature and pression, and that they were inde- 

 pendent of the intermediate circumstances through which the fluid 

 passed. If these were true, the same result would be obtained in these 

 two cases : air is condensed to 10 atmospheres in a vase which is placed 

 so charged in a calorimetre, or furnace ; at a specified moment the ca- 

 pacity of the recipient is suddenly doubled, necessarily the pression 

 descends to 5 atmospheres, and this dilation produces a cold which 

 may be appreciated by the thermometer. On the other hand, place 

 in the same furnace two reservoirs of the same capacity, exhaust the 

 air in one, in the other condense the air to ten atmospheres. The ap- 

 paratus having reached a state sufficiently stationary for a delicate 

 observation, communication between the two reservoirs is suddenly 

 made ; the gas spreads, as before, in a double space, as the pression as 

 before is reduced to 5 atmospheres. Who would not expect to witness, 

 as in the other case, a decline of temperature ? Yet no such thing 

 takes place ; the column of mercury in the thermometer remains per- 

 fectly stationary ! This experiment, imagined by M. Joule, acknow- 

 ledged to be exact by M. Regnault, is certainly very remarkable, and 

 all natural philosophers will be greatly struck by it. If the initial and 



