ksTi«^» Theory of Heat to the Steam-engine. 433 



vapour entering the vicious space with greater velocity, the vis 

 viva of its motion is converted into heat, which in its turn causes 

 the evaporation of the accompanying Hquid; and secondly, 

 because the vapour before present in the vicious space contri- 

 butes to the increase of the ultimate quantity of vapour. 



Substituting both the above values of V in the first of equa- 

 tions (XVIII), and in the one case again making € = 0, whilst in 

 the other 6=0-05, we have as the corresponding quantities of 

 work expressed in kilogramme-metres, the numbers 



.'^•<>^^'<^- 14990 and 14450. 



According to Pambour^s theory, it makes no difference whether 

 a part of the volume is vicious space or not j in both cases this 

 volume is determined from the equation (29Z>) by giving to p the 

 particular value jOj. By so doing we obtain 



0-3883. 



This value is greater than the one (0*3637) before found for 

 the same quantity of vapour, because hitherto the volume of 

 vapour at its maximum density was esteemed greater than, 

 according to the mechanical theory of heat, it can be, and this 

 former estimate also finds expression in equation (296). 



If, by means of this volume, we determine the work under the 

 two suppositions 6=0 and 6=0*05, we have 



16000 and 15200. 



As might have been concluded immediately from the greater 

 volume, these quantities of work are both greater than those 

 before found, but not in the same ratio ; for, according to our 

 equations, the loss of work occasioned by vicious space is less 

 than it would be according to Pambour^s theory. 



53. In a machine of the kind here considered, which Pambour 

 actually examined, the velocity which the machine actually pos- 

 sessed, compared with the minimum velocity calculated, according 

 to his theory, for the same intensity of evaporation and the same 

 pressure in the boiler, gave the ratio 1*275 : 1 in one experiment, 

 and in another, where the charge was less, 1'70 : 1. These velo- 

 cities would in our case correspond to the volumes 0*495 and 

 0*660. As an example of the determination of work, we will 

 now choose a velocity between these two, and set simply, 



V = 0*6. (.>xr ; ^v. 



In order next to find the temperature t^ corresponding to this 

 value of V, we employ the equation (47) under the following 

 special form : — 



T2^2=^6577 + 56*42 . (^1-^2) -0*0483 . [p^-p^, (55) 



