"PRELIMINARIES TO A TEST,-T. In preparing for and conducting trials of steam-boilers, the specific object of the proposed trial should be clearly defined and steadily kept in view.
" 11. Measure and record the di W12810718, position, etc., of grate and heating surfaces, flues and chimneys, proportion of air space in the grate-surface, kind of draft, natural or forced.
" I I1. Pat the Boiler in Good Co»dition.-11ave heating surface clean inside and out, grate bars and sides of furnace free from clinkers, dust and ashes removed from back connections, leaks in masonry stopped, and all obstructions to draft removed. See that the damper will open to full extent, and that it may he closed when desired. Test for leaks in masonry by firing a little smoky fuel and immediately closing damper. The smoke will then escape through the leaks.
" IV. Hare en understanding with the parties in whose interest the test is to be made as to the character of the coal to be used. The coal must he dry, or, if wet, a sample must be dried carefully and it determination of the amount of moisture in the coal made, and the calculation of the results of the test corrected accordingly. Wherever possible, the test should be made with standard coal of a known quality. For that portion of the country east of the Alleghany Mountains good anthracite egg coal or Cumberland semi-bituminous coal may be taken as the standard for making tests. West of the Allegheny Mountains and east of the Missouri River, Pittsbnrg lump coal may be used.* "V. In all important tests a sample of coal should be selected for chemical analysis.
"VI. Establish the correctness of all apparatus used in the test for weighing and measur ing. These are : 1. Scales for weighing coal, ashes, and water. 2. Tanks, or water-metres for measuring water. Water-metres as a rule should only be used as a check on other meas urements. For accurate work, the water should be weighed or measured in a tank. 3. Ther
mometers and pyrometers for taking temperatures of air, steam, feed-water, waste gases, etc. 4. Pressure-gauges, draft-gauges, etc.
"VII. Before beginning a lest the boiler and chimney should be thoroughly heated to their usual working temperature. If the boiler is new, it should be in continuous use at. least a week before testing, so as to dry the mortar thoroughly and heat the walls.
" VIII. Before beginning a test the boiler and connections should he free from leaks. and ViiiI. Before beginning a test the boiler and connections should he free from leaks. and all water connections, including blow and extra feed-pipes. should be disconnected or stopped with blank flanges, except the particular pipe through which water is to be fed to the boiler during the trial. In locations where the reliability of the power is so important that an extra feed-pipe must be kept in position, and in general when for any other reason water-pipes other than the feed-pipes can not be disconnected, sueh pipes may be drilled so as to leave openings in their lower sides, which should be kept open throughout the test as a means of detecting leaks, or accidental or unauthorized opening of valves. During the test the blow off pipe should remain exposed. If an injector is used it must receive steam directly from the boiler being tested, and not from a steam-pipe, or from any other boiler. See that the steam-pipe is so arranged that water of condensation can not run back into the boiler. If the steam-pipe has such an inclination that the water of condensation from any portion of the steam-pipe system may run back into the boiler, it must be trapped so as to prevent this water getting into the boiler without being measured.