This gives very important economical results; for if the cost of the Dowson gas given in the tables as 4¼d., 3-1/3d., and 2¾d. per 1,000 cubic feet, be multiplied by 5 there will be 1s. 9¼d., 1s. 4¾d., and 1s. 2¾d., or a mean of 1s. 5½d. for the equivalent of 1,000 cubic feet of coal gas, which usually costs from 3s. to 4s., and this represents an actual saving of about 50 to 60 per cent, in working cost. Another practical consideration is that coal gas requires 224 lb. to 250 lb. of coal per 1,000 cubic feet of gas, but the writer requires only 12 lb. per 1,000 cubic feet, and multiplying this by 5 to give the equivalent of 1,000 cubic feet of coal gas, for engine work, there are 60 lb. instead of 224 lb. to 250 lb. This is only 24 to 27 per cent, of the weight of the coal required for coal gas, and in many outlying districts this will effect an appreciable saving in the cost of transport. APPENDIX. TABLE I. _Generator A Size_ (producing 1,000 cubic feet per hour): Anthracite to make gas at the rate of 1,000 s. d. cubic feet per hour=l2 lb x 9 working hours=l08 lb., or say, 1 cwt. at 20s. a ton.................................... 1 0 Allowance for wages of attendant......... 1 0 Repairs and depreciation of generator, gasholder, etc. (5 per cent. on £l25)= per working day........................ 0 5 Interest on capital outlay, ditto........ 0 5 ______ Total........................... 2 10 cub. ft. Gas produced............................. 9.000 Less gas used for generating and superheating steam..................... 1,000 _____ Total effective gas for 2s. 10d. 8,000 Net cost 4¼ d. per 1,000 cubic feet. TABLE II. _Generator B Size_ (producing 1,500 cubic feet per hour) Anthracite to make gas at the rate of 1,500 s. d. cubic feet per hour=18 lb. x 9 working hours=162 lb., or, say, 1½ cwt. 20s. a ton.................................. 1 6 Allowance for wages of attendant......... 1 0 Repairs and depreciation of generator, gasholder, etc. (5 per cent, on £140) =per working day....................... 0 5½ Interest on capital outlay, ditto........ 0 5½ ___ ___ Total........................... 3 5 cub. ft. Gas produced............................. 13,500 Less gas used for generating and superheating steam..................... 1,200 ______ Total effective gas for 3s. 5d.. 12,300 Net cost 3 1/3d. per 1,000 cubic feet. TABLE III.