4G 



REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



[44] 



Large boat. Small boat. 



Diameter of furnace inches.. 



Area of grate surface square feet.. 



Diameter of smoke-pipe inches.. 



Height of smoke-pipe above grate bars feet.. 



Diamoter of separator inches.. 



Height of separator do 



Steam cylinders number.. 



Diameter of high-pressure cylinder inches. . 



Diameter of low-pressure cylinder do 



Stroke of pistons do 



Diameter of the piston rods do 



Diameter of the air pump (single-acting) do 



Stroke of air pump do 



Diameter of circulating pump-plunger do 



Diameter of feed pump-plunger do 



Stroke of pumps do 



Length of condensing pipes feet.. 



Condensing surface square feet.. 



Main. journals. number.. 



Diameter of main journals inches.. 



Length of main journals do . . . 



Crank -pin journals number.. 



Diameter of crank-pin journals : 



High-pressure inches . . 



Low-pressure do 



Length of crank-pin journals : 



High-pressure do 



Low-pressure do 



Space occupied by the engine : 



Length fore and aft do 



Width do ... 



Height do ... 



Diameter of the screw propeller do 



Pitch of the screw propeller (uniform) do 



Projected length of the screw on line of its axis do 



Blades of the screw number.. 



Friction of the pitch used 



Helicoidal area of the screw blades square feet.. 



Weight of the screw pounds.. 



29 



22 



4.58 



2.64 



10 



8 



8. 75 



6.75 



6 



3 



31 



26 



2 



2 



34 



24 



6 



4i 



7 



5 



i 



7 

 IE 



24 



2i 



n 



2J 



7 

 IB 



* 



ft 



8 



7 



5 



15 



13 T V 



9.83 



4.95 



3 



3. 



li 



]Jand2J 



3 



2* 



2 



2 



li 



14 



I 



A 



n 



1 



H 



li 



24J 



21 



21 



18 



44 



26 



28 



164 



48.72 



30 



5 



3 



4 



2 



0.49 



0.2 



3.69 



4 



45 



6 



DREDGING ENGINE. 



Plates XXIII aud XXIV represent the dredging engine, the principal 

 use of which is to hoist the trawls and dredges, but it is provided with 

 additional "gypsy heads" for hoisting boats, &c. It was built by 

 Copeland & Bacon, of Xew York, according to their patents. It has 

 three gypsy heads (the large one of steel) mounted on the same hori- 

 zontal shaft, and driven by a double-cylinder half-trunk steam-engine 

 through the intervention of toothed gearing and a modification of 

 Mason's friction clutch. The engines have locomotive valves which are 

 actuated by Stephenson's links aud eccentrics ; the cranks are cast-iron 

 disks; each pair of eccentrics is cast in one; the cut-off is effected by 

 the lap on the valves. The machine has a friction brake to regulate the 

 " paying out" of the dredge rope, and also a roller guide, with treadle 

 motion, to press the rope aside and prevent the turns from riding. The 

 engine is placed on the main deck, forward of the foremast; it takes its 

 steam from the main boilers and may be exhausted either into the 

 main condenser or into the atmosphere. 



Its principal dimensions are as follow : 



Greatest diameter of the large gypsy head inelies.. 36| 



Least diameter of the large gypsy head do 22-{-{j 



Length of the large gypsy head on line of its axis do 24 



Diameter of the inboard end of the small gypsy heads do 21£ 



