THEORY OF THE STEAM ENGINE. CXLI. 
far experimented on, it has been found that the consumption of 
dry steam per indicated horse power hour is independent of the 
quality of the entering steam. 
(j) Such conditions of working as steam jacketing, superheating 
and compounding do not come within the scope of this paper. 
Their adoption in any particular steam engine of course completely 
alters the mode of variation of the heat losses. 
The introduction of air into the cylinder has been found’ to 
have a beneficial influence in lessening the initial condensation, 
bat owing to practical difficulties the plan has never been widely 
adopted. 
In attempting to determine the principles governing “ cylinder 
condensation ” the usual plan has been to select one particular 
working condition, (such as speed or initial pressure) and, keeping 
all other working conditions constant, to make a series of tests 
with different values of this one condition. Then the cylinder 
condensation for each test is computed, and the quantities thus 
obtained are co-ordinated with the respective values of the working 
- condition under investigation. From the curve so determined 
the form of the function connecting the two is derived. This 
process repeated for all the other working conditions would 
similarly fix their corresponding functions. Messrs. Gately and 
Kletsch, under the direction of Prof. Thurston, were the first to 
take up this systematic experimental study of the cylinder losses,” 
and they have been followed by a very large number of others. 
The actual result of so much investigation is not as great as it 
might be had more attention been paid to the systematic planning 
of each series of tests. To completely determine the mode of 
variation of cylinder condensation with all the different working 
conditions a series of tests should comply with the following 
requirements :— 
1. The greatest possible range of variation of each condition 
Should be obtained. 
1 London Engineering 1873. 2 Journ. Frank. Inst., October 1835. 
