SKILL IN ENGINE FIRING.

Otago Witness, Issue 1319, 10 March 1877, Page 3

SKILL IN ENGINE FIRING.

People do not generally give to the fireman credit for the skill his occupation embraces and demands. We have record of some experiments made for a prize in an English contest which are interesting and suggestive. The tests were made with a small motor, but the points involved are of general application. The Royal Agricultural Society of England offered prizes for the best driver of a portable engine. The first prize wa3 £5 and a silver medal, and the second and third prizes consisted each of £2 10s. and a silver medal. The Engineer says : — The tests were carried but in the following way :— An eight horse-power agricultural locomotive was provided. The engine was fitted with a friction brake, such as is used by the Royal Agricaltural Society, and a counter. The brake was loaded to 22*5 horse-power. The engine was handed over successively to the different competitors, 21 in number. Each man was supplied with 210 lbs. of coal and 8 lbs. of wood, and as much oil and tallow as he required was weighed out to him, the quantities being carefully noted. He was then left to fire and drive as he pleased, without interference, except to warn him that he was running his engine too fast or too slow. The standard of efficiency was the number of revolutions got out of the engine. Without going into details, we may say that after five days' work, the four best men competed a second time, the result being that the first prize was awarded to John Waters, who got 13,967 revolutions out of his engine ; the second to J. Snashall, with 13,366 revolutions ; and the third prize to J. Gardiner, with 13,258 revolutions. Turning to the log sheets, we find the following comments by the judges, Messrs R. J. Sankey and Thomas Aveling. Against Waters we have : — "Tubes swept; cylinder lubricated often, and engine oiled ; damper closed ; reversing lever maintained by a small wedge just behind the fifth notch. Coals well broken and wetted; pressure very regular at 90 to 98 lbs ; firing very good, ashes burned." Very nearly similar entries jwere made by the judges for the two other prize men, from which it appears that they understood what they were about. We may call special attention to the use made of his expansion gear by Watera, who, finding that he could do little better with the link in one place than another, compensated for the want of sufficiently minute divisions in the sector of the reversing gear by wedging the latter just where he wanted it.

We may be asked what all this amounts to, and what is proved by the fact that Waters ran cff 13,967 revolutions ] The actual running time was 91 minutes ; the mechanical time was 93 minutes, and the

compensation of fuel was 6*45 lbs. per brake horse-power per hour. Now, it must be borne in mind that none but tolerably good men, men with some reputation as drivers, competed. If we turn to the log of the man wh© did the worst during the trial, we shall see what the difference between good and bad firing and driving comes to. The smallest number of revolutions obtained was 7942, the running time being 59 minutes only ; the mechanical time was just under 53 minutes, and the consumption of fuel was consequently over 113 pounds of coal. This is to say the worst man used nearly twice as much coal per horse per. hour as Waters. Theformer's driving seems to have been unsatisfactory throughout. The reversing lever was frequently changed from one notch to another, and the damper was altered several times ; the speed of the engine was very irregular. We have thus the plainest possible evidence that the saving which can be effected in fuel by a skilful man is a very important item in the economy of engine power.