HOW THE TESTS WERE CONDUCTED. 35 



formula for determining the steam accounted for by the indica- 

 tor is used as that given above, but it must be adapted to the 

 type of engine. The only change required in the formula is 

 in the mean effective pressure. Here the quantity used when 

 determining the steam accounted for in any given cylinder is 

 the collective mean effective pressure cf all the cylinders 

 assumed to be referred to the one under consideration. In the 

 case of the high-pressure cylinder of a compound engine the 

 quantity to be used is the sum of the mean effective of the H. P. 

 cylinder and a quantity representing the m.e.p. of the low-pres- 

 sure cylinder referred to the high-pressure cylinder ; that is, the 

 mean effective pressure in the low-pressure cylinder multiplied 

 by the ratio of the volume of the L. P. cylinder to the H. P. 

 cylinder. If the ratio is 4 to 1, the m.e.p. of the low-pressure 

 cylinder is to be multiplied by four to determine the quantity 

 desired. Likewise the quantity to be used for computing the 

 steam accounted for in the low-pressure cylinder is the sum of 

 the mean effective pressure in that cylinder, and the mean effec- 

 tive pressure in the H. P. cylinder divided by the ratio of the 

 volume of the L. P. cylinder to the H. P. cylinder. In the 

 instance given it would be the mean effective in the H. P. 

 cylinder divided by 4. In a triple expansion engine the mean 

 effective pressure to be used for computing the steam accounted 

 for in the L. P. cylinder is the sum of the mean effective pres- 

 sure of that cylinder; that of the m. e. p. of the H. P. cylinder 

 divided by the ratio of volume of the L. P. cylinder to that of 

 the H. P. cylinder, and the m.e.p. of the intermediate cylinder 

 divided by the ratio of the volume of the L. P. cylinder to that 

 of the intermediate cylinder. Likewise the quantity to be used 

 for the intermediate cylinder is the sum of three quantities, 

 namely, the m.e.p. of the intermediate cylinder, the m.e.p. of 

 the H. P. cylinder divided by the ratio of the volume of the 

 intermediate cylinder to that of the H. P. cylinder, and the 

 m.e.p. of the L. P. cylinder multiplied by the ratio of the volume 

 of the L. P. cylinder to that of the intermediate cylinder. 



As an example of the proper method of computing the equiv- 

 alent mean effective pressure referred to either cylinder of a 



