586 The Trials of Light Portable Motors at Plymouth. 
carefully by Mr. Anderson with Crosby indicators. The feed 
was in all cases measured by weighing. 
For the purpose of the trial a supply of Powell-Duffryn 
Welsh coal had been provided, and this was given in weighed 
quantities as required to each competitor. Samples of this coal 
taken at intervals during the trials were sent to Mr. Charles J. 
Wilson for anarysis, with the following results : — 
Analysis of Coal received from Messrs. Easton & Anderson, 
June 28, 1890. 
Moisture 1*01 per cent. 
Ash 4-73 
Carbon 84-87 
Hydrogen . . . . . . . 4 - 38 
Sulphur, nitrogen, oxygen, &c 5 Ol 
10000 
Heating value — 
0-8487 x 8,080 . . . . = 6857-5 
0-0438 x 29,000 . . . . = 1270-2 
8127-7 
8127*7 
Evaporation in lb. of water per lb. of coal - T = 15-13, or deduct- 
ing weight of moisture present, evaporation per lb. of coal as used in the 
trials, 15 12. 
The coal was therefore of excellent quality. 
Before commencing the trials the brake load was adjusted 
to give as nearly as might be the horse-power which the exhibitor 
thought best. The engine was then kept running steadily for 
some time, with the brake on, and the fire regulated to keep 
the pressure constant. Just before beginning the trial, the 
charging of fresh fuel was stopped till the pressure gauge 
showed a slight fall. Then the condition of the fire and water 
gauge was noted and the trial commenced. The steam pressure 
was kept very constant throughout the trials. Some time 
before the end of the trials the fire was cleaned, and it was 
brought at the end of the trial to the same condition as at first. 
The feed was also regulated at the end of the trial, so that 
the level in the gauge was the same as at the beginning. 
Discussion of the Results. . 
The Boilers. 
The portable steam motor consists of two parts, and it is 
obvious that it is necessary to distinguish the efficiency of the 
boiler and the engine. The motor may have had a good boiler and 
