The preceding table shows the results of comparative trials made in winter with different sorts of fuel, under exactly similar conditions as to type of engine, profile of line, and load of train.  Two sets of comparative trials were made, both of them in winter.  The three engines used were some of those built by Schneider.  In comparison with anthracite, the economy in favor of petroleum refuse was 41 per cent. in weight, and 55 per cent. in cost.  With bituminous coal there was a difference of 49 per cent. in favor of petroleum as to weight and 61 per cent. as to cost.  As compared with wood petroleum was 50 per cent. cheaper.  At a speed of fourteen miles an hour up an incline of 1 in 125 the steam pressure was easily kept up at 9 to 91/2 atm. with a No. 9 injector feeding the boiler all the time.

Up to the present time the author has altered seventy-two locomotives to burn petroleum; and from his own personal observations made on the foot plate with considerable frost he is satisfied that no other fuel can compare with petroleum either for locomotives or for other purposes.  In illustration of its safety in case of accident, a photograph was exhibited of an accident that occurred on the author’s line on 30th December, 1883, when a locomotive fired with petroleum ran down the side of an embankment, taking the train after it; no explosion or conflagration of any kind took place under such trying circumstances, thus affording some proof of the safety of the petroleum refuse in this mode of firing.  Although it is scarcely possible that petroleum firing will ever be of use for locomotives on the ordinary railways of coal-bearing England, yet the author is convinced chat, even in such a country, its employment would be an enormous boon on underground lines.

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CHARCOAL KILNS.

[Illustration:  KILN FOR BURNING CHARCOAL.]

In answer to the inquiry of a correspondent about charcoal making, we offer two illustrations that show a method of manufacture differing from that usually adopted, which is that of burning on the bare ground, and covering with soil or sods to exclude the air.  These kilns are made of brick, one course being sufficient, bands of iron or timber framework being added to strengthen the brickwork with greater economy.  The usual style is conical, and the size is 24 feet in diameter, with an equal height, holding about 40 cords of wood.  The difference in price is 1-1/8 d. per bushel in favor of these kilns as compared with the usual mounds, the burner being furnished with the use of the kilns, and the timber standing, the kiln burning costing 2-1/8 d., and the other 3-1/4 d.  The kilns must be lined to about halfway up with fire-brick, the cost of which will vary with the locality, but will be about L200, and as 40 to 50 bushels of coal have been made per cord the extra yield on good charcoal and the lessening of the cost of making soon covers any