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readings were found to be considerably below what they should be, owing probably, to the fact that the bulb end of the stem was too short to reach sufficiently into the interior of the steam-pipe. The pyrometer for uptake indicated satisfactorily during the trials of the 9th and 10th instants, but the latter date it became deranged and no longer furnished any indications, but from what cause is unknown.

The third test for the purpose of determining whether, with the diaphragm plate removed from the back connection, the operations of firing, cleaning of fires, etc., could be performed in one furnace while the blast was on the other, was made on the after starboard boiler on the 11th instant. For this purpose the diaphragm plate was removed, steam raised on the boiler, and a moderate blast used to put the fires in the condition of ordinary working practice. The blast was then reduced to a pressure in the main conduit of 1 inch of water and closed off from one furnace and the door of that furnace opened; the blast was then gradually increased up to 24 inches of pressure. The same thing was then done to the other furnace with like results in the two cases.

At 1 inch pressure in main conduit there was but a moderate discharge of furnace gases into the fire-room, and the fires could be worked with little inconvenience; at 1 inches pressure, there was a constant escape of gas with flame, extending up the boiler front for about 3 feet, and sufficient to entirely prevent working in front of the fires; at 2 inches pressure of blast in main conduit the flame was projected in a curve to beyond the middle of the fire-room and as high as the spar deck, with so much heat that it would have been difficult to pass on the opposite side of the fire-room, and with 24 inches pressure in the main conduit, a solid column of white flame was projected entirely across the fire-room with very intense heat. These results indicate beyond question that it would be entirely impracticable to omit the diaphragm plates from the back connections. It may be further remarked that when the blast was at a pressure of 5 or 6 inches, even with the diaphragm plates in place, the leakage past it was sufficient to project a good deal of gas and very uncomfortable flame out of the furnace door when working the fires.

Respectfully submitted,

Engineer-in-Chief GEO. W. MELVILLE, U. S. N.,

A. S. GREENE,

Chief Engineer, U. S. Navy. J. L. D. BORTHWICK,

Chief Engineer, U. S. Navy. A. PRICE,

P. A. Engineer, U. S. Navy.

Chief of the Bureau of Steam Engineering,
Navy Department, Washington, D. C.

TABLE 1.-Calorimeter measurements, evaporative test, U. S. S. Swatara, with circulating plates in place, navy-yard, Portsmouth, N. H., February 9, 1888.

Weight, in pounds, of—

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