Measurements and Observations. 
175 
Anthracite. 
Full load : 1*1 lb. per B.H.P. hour, including fuel 
needed for starting and for banking during the night. 
Half load : 1*6 lb. per B.H.P. hour, including coal 
for starting. 
Water : 1 gallon per B.H.P. hour at full load and 
f gallon at half load. 
Coke. 
Full load: 1*3 lb. per B.H.P. hour, including fuel 
needed for starting. 
Water : 1^ gallons per B.H.P. hour at full load. 
The following deduction can also be made from these 
trials : — 
“Assuming a 20-brake-horse-power plant to start on Monday morning with 
an empty producer, and to run ten hours per day on full load for a week, 
banking the fires at night, the consumption of anthracite peas would be about 
half a ton for the week, and about three-eighths of a ton if the average load is 
about half full load. With coke the consumption is about 25 per cent. more. 
From 2,000 to 3,000 gallons of water per week are required for a 20-brake- 
horse-power plant to provide water for the scrubber and the producer, and of 
this by far the larger part would be used in the scrubber.” 1 
Figs. 9 to 25, pp. 177 to 182, are photographic reproductions 
of certain indicator and Mathot diagrams selected from the 
large number that were taken during the trials. 
Fig. 9 was taken from the National engine, when running 
at full load, and requires no comment ; it is just a good ordinary 
indicator card. 
Fig. 10 is the Mathot card for the same engine also taken at 
full load, and each of the vertical lines (except the very short 
ones) corresponds to an indicator diagram like Fig. 9, and the 
height of these lines corresponds to the maximum pressure of 
the indicator diagram. As both diagrams were taken with the 
same spring, (that is, 1 in. represents 300 lb. per square 
inch), it will be seen that the full line in Fig. 9 corresponds 
to a line of average height in Fig. 10, the top dotted line to one 
of the longer lines, and the lower dotted line to one of the 
shorter lines in Fig. 10. It will be noticed that the area of the 
indicator card is not substantially altered by the amount of the 
maximum pressure, and this fact must be borne in mind when 
studying the Mathot diagram ; that is, the mean pressure of each 
diagram is by no means proportionate to the height of the lines 
on the Mathot diagram. The very short lines on the Mathot 
diagram show the compression reached when the gas valve is 
shut, that is, before a “ miss ” stroke ; and this compression 
pressure is less than that reached before an explosion stroke. 
1 “ Suction Gas Plants.” Paper read by Professor W. E. Dalby, M.A., B.Sc.. 
before the British Association, August, 1906. 
