COMPARISON OF DIFFERENT KINDS OF FUEL. 49 



cite egg, and 95.1 horse-power with a mixture of equal parts 

 of screenings and Cumberland coal. Boiler No. 12, rated at 

 87 horse-power, gave 84 horse-power with anthracite broken 

 coal, 105.4 horse-power with Cumberland, and 82.2 horse- 

 power with a mixture of two parts screenings and one part 

 Cumberland, The draught was 0.28 inches. Boiler No. 17, 

 rated at 129 horse-power, gave 192.3 horse-power with anthra- 

 cite broken coal, draught 0.11 inches; 149.2 horse-power 

 with pea coal, draught 0.12 inches; and 157.1 horse-power 

 with 44 parts pea and dust and 37 parts culm, draught 0.28 

 inches. Vertical boiler No. 54, rated at 140 horse-power, 

 gave 94 horse-power with Cumberland coal, draught 0.07 

 inches; 103.8 horse-power with anthracite broken, draught 

 0.05 inches ; and 118.1 horse-power with two parts screenings 

 and one part Cumberland, draught 0.32 inches. Boiler No. 

 36, rated at 270 horse-power, gave 196.1 horse-power with 

 anthracite broken coal, draught 0.25 inches; 214.6 horse- 

 power with Cumberland coal, draught 0.20 inches ; and 204.8 

 horse-power with 6 parts screenings and 4 parts Cumberland, 

 draught 0.31 inches. It is seen, therefore, that as regards 

 capacity, Cumberland coal secures the largest power with a 

 given draught, and pea coal or mixtures of screenings and 

 bituminous coal the least. This suggests that to secure the 

 same capacity from a given boiler with different kinds of coal, 

 the area of grate surface must be varied to suit the varied 

 kinds of coal. In the case of Boiler No. 9, for example, the 

 grate would have been increased in the proportion of 95.1 to 

 143.8 when the mixed fuel was used, in order to bring the 

 amount of power developed up to that obtained with Cumber- 

 land coal. 



Among the tests given in the paper are a few made with 

 other kinds of fuel than those upon which the comparisons are 

 made. 



There are several with chestnut No. 2 " anthracite, which 

 corresponds in size to the pea grade. The evaporation, and 

 the cost also, are about the same as with pea coal. 



Two tests are given where Walston bituminous coal was 



