BRECK ENKIDGE.] 
STEAM TESTS. 
(b 
The boilers were cleaned externally after each test. The interior 
condition of each boiler was practically clean during all of the tests. 
Leading proportions of Heine water-tube boilers used in coal-testing plant. 
1 1 * -in 
No. 
Item. 
1 Rated capacity of boiler horsepower. . 
2 Water-heating surface square feet . . 
3 Superheating surface 
4 Grate area s< juare feet . . 
5 Kind of draft 
6 Height of steel stack feet. . 
7 Area of steel stack square feet. . 
8 Number of tubes 
i< Outside diameter of tubes inches. . 
10 Steam pressure pounds. . 
11 j Observations taken every 20 minutes. 
12 Approximate duration of each trial hours. . 
Dimensions. 
210 
2,031 
None. 
40.0 
Natural. 
L15 
7.07 
116 
3. 5 
85 
10 
DESCRIPTION OF THE STEAM ENGINE AND GENERATOR. 
The steam generated by the boilers was largely used by an Allis- 
Corliss engine of 250-horsepower capacity, and the power of the engine 
was absorbed by a 200-kilowatt direct current, 240- volt Bullock gen- 
erator, to which the engine was belted. 
The engine was the simple noncondensing t}^pe. The cylinder was 
22 inches in diameter and the stroke was 42 inches. The engine ran 
about 80 revolutions per minute. 
Numerous tests made to determine the steam consumption of the 
engine, as well as the mechanical efficiency of the engine and generator 
together, gave the following average results: 
Average results of engine and generator tests. 
Number of pounds of steam used per hour per indicated horsepower developed 
by the engine 23. 60 
Mechanical efficiency of the engine and generator combined (per cent) 81 
From these figures has been calculated the electrical horsepower 
delivered to the switchboard for such tests of the boilers as were not 
accompanied by a test of the engine and generator. 
COALS TESTED. 
On pages 76 to 78 the coals tested are arranged alphabetically 
according to the States from which they were obtained. Some of 
these coals were washed and some were briquetted. In all tests of 
coals other than slack, the coal was first passed through rolls having 
