a = 4347826 b = 618.
On the Expansive Action of Steam.
The investigation of the effect of the expansion of steam which has been given in the text, is intended to convey to those who are not conversant with the principles and language of analysis, some notion of the nature of that mechanical effect to which the advantages attending the expansive principle are due. We shall now, however, explain these effects more accurately. [Pg512]
The dynamical effect produced by any mechanical agent is expressed by the product of the resistance overcome and the space through which that resistance is moved.
Let
| P = the pressure of steam expressed in pounds per square foot. |
| S = the number of cubic feet of steam of that pressure produced by the evaporation of a cubic foot of water. |
| E = the mechanical effect produced by the evaporation of a cubic foot of water expressed in pounds raised one foot. |
Then we shall have E = PS; and if W be a volume of water evaporated under the pressure P, the mechanical effect produced by it will be WPS.
By (10.) we have
| SP = a − bS. |
Hence, for the mechanical effect of a cubic foot of water evaporated under the pressure P we have