dep:p-sea exploration. 
271 ) 
There is a single smokestack, 10 feet of its base being formed by the steam- 
drum, which acts as a. superheater. The grate bars are double and in two lengths. 
The following are tlie general dimensions of the two boilers and accessories: 
Niinilier, 2. 
l.eugtli, 10 feet 3 inches. 
Diameter, 12 feet. 
Niimher of furnaces eacli, 3; type, plain cylin- 
drical, 3 sections, Adamson’s rings. 
Length of furnaces, 7 feet; diameter, 3 feet. 
Grate surface, 21 square leet for I'urnace, 63 square', 
feet for hoiler; total grate surface, 126 .srp ft. 
Heating surface, 1,467 S(|uarefect; total lieating 
surface, 2,934 square feet. 
Ratio of heating surface to grate surface, 23.3 to 1. 
Number of tubes in each boiler, 197; material, 
brass; length, 7 feet 4 indies; diameter, ex- 
ternal, 3 inches; thickness, No. 12 wire gauge. 
Thickness of shell, f inch; of heads, inch; of 
tube sheets, f inch; of furnaces, 4 inch; of con- 
nection sheets, ^ inch. 
Weight of each boiler, exclusive of gr.ate bars, 
62,333 pounds. 
Weight of water in e.ach boiler (6 inches above 
tubes), 31,833 pounds. 
Weight of grate bars, each lioiler, 4,000 pounds. 
Total weight of both boilers, with water and grate 
bars, 196,332 pounds. 
Working pressure above atmosphere, W pound.s. 
fsteam drum : 
Material, American charcoal iron. 
Length, 10 feet. 
Diameter, 7 feet 4 inches. 
Diameter of Hue, 4 feet 4 inches. 
Ca]uicity, 2.56 cubic feet. 
Smokestack : 
Total length .above the grate bars, .50 feet. 
Diameter, 4 feet 4 indies. 
Weight, 3,600 pounds. 
Propellers ; 
Number, 2. 
Type, 4-bladed, twin-screw, right and left. 
Nlaterial, composition, 88 cu. 10 sn. 2 zu. 
Pitch; Port, 13 feet 11 inches; starboard, 14 
feet inch. 
Diameter: Port, 8 feet 11| inches ; starboard, 
9 feet ^ inch. 
Ildicoidal are.a; Port, 30 square feet; star- 
board, 30 squ.are feet. 
Weight: I’ort, 3,277 pounds; starboard. 3,223 
pounds. 
STEAM PUMPS. 
The Allxdrosfi is provided with six Davidson steam iminps, as follows: 
Xo. 1. The (•irciilating pump is piped to take water from the sea or I'rom the bilge, 
and to disch:irge into the condenser. Its speed may be varied from I to nearly -00 
strokes per minute. 
Xo. 2. The boiler feed and lire immp has sea and liilge connections, and delivers 
to the boilers, to the hydrant pipe, engine-room, fire-room, ash-chute, and overboard at 
pleasure. It is designed to work under great pressure. The hydrant pipe runs fore 
and aft under the main-deck beams and has connections at convenient intervals on 
both sides of the deck-house for lire and general ]mrposes. 
