MADE IN THE EFFICIENCY OF STEAM ENGINES IN CORNWALL. 125 
a weight rolling in each direction, and acting through the medium of an 
escapement similar to that of a clock. 
In the year 1 793, that is fifteen years afterwards, an account was taken of 
the work performed by seventeen engines on Mr. Watt’s construction, then 
working in Cornwall. This statement is not verified in the authentic manner 
of the former ; but there do not appear to be any reasons for doubting of its 
correctness. The average duty was 19’569000 pounds of water raised one foot 
high, by the consumption of one bushel of coal ; exceeding the standard expe- 
riment on the two atmospheric engines in the proportion of 2.78 to 1, or nearly 
as 2-t- to 1. So that work requiring by the atmospheric engines 278 bushels of 
coal, would be performed by Mr. Watt’s steam engine by 100 bushels, con- 
sequently 178 would be saved. One third part of these must have been paid 
to Messrs. Boulton and Watt as patentees, leaving a clear gain to the mine 
of 118 bushels, being more than the quantity consumed. 
Some years later, disputes took place as to the real performance of Mr. Watt’s 
engines, and a reference was agreed on between the parties to five individuals, 
of whom I had the honour to be one ; and in May 1798 returns were made 
by the agents in various mines, of all the particulars respecting twenty-three 
engines, from which I then deduced their respective duties for the information 
of the referees. 
It will not be necessary to trouble the Society with more of these particulars 
than the diameter of the cylinder, whether it worked single or condensed, both 
above and below, and the final result or duty in millions of pounds lifted one 
foot high by the consumption of one bushel of coals. 
