12 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 



the air-pump motion, 4 iucbes in diameter aud 12 inches stroke ; com- 

 position plunger, valves, and seats ; also a by-pass valve and air-ves- 

 sel. 



Bilge-pum}) is an independent steam-pump of the Davidson pattern, 

 valves of rubber, composition seats, guards, and stems, and copper air- 

 chamber. This pump has connections through a "manifold" to the 

 various water-tight compartments ; also, in the event of breakage of 

 the auxiliary pumj), can be used in lieu of that pump, having the same 

 <^.onnections. 



Gross-heads are of wrought iron, finished and fastened to piston-rod 

 by a nut secured by a '-dowel." Journals are 2| inches diametes- and 

 31 inches long-. Cross-heads move upon composition slipper slides work- 

 ing in a cast-iron guide. The bottom slipper has a bearing surface of 

 80 square inches. Both top and bottom gibs can be readily removed. 



8Ude-ralve stems are of mild steel; those for main valves are 1| inches 

 diameter, and cut-off valves If inches diameter; stuffing boxes and 

 glands are bushed with composition. 



Eccentrics and rods. — There are two eccentrics for each main ^■alve, 

 with a " Stephenson " link of wrought iron connected by the proper rods. 

 For each cut-off valve, there is one eccentric to one end of a link, and 

 the opposite end of the link is held in i)osition by a proper rod in con- 

 nection with a concentric disk on the crank-shaft. This link is adjusted 

 by a hand-lever working against an arc, which is marked for the <liffer- 

 ent points of cut-off. The straps are of (;omposition, ribbed and "' bab- 

 bitted." Eccentric rods are of wrought iron, and connected to links so 

 as to be adjusted for wear. Links and pins are case-hardened and 

 link-blocks are of composition. 



Connecting-rods are of wrought iron, forked at the cross-head end aud 

 finished, 5 feet 11 inches long between centers; crank-end neck 2§ 

 inches diameter and fork-end 2| inches diameter. Boxes for cross-head 

 and crank-pin journals are of composition and secured by wrong ht-iron 

 jstraps with gibs and keys; keys secured by steel set-screMs. 



Main pilloic-hlocls are cast with the bed-plate, and the lower part of 

 the box is of i>hosphor-bronze. After journal Gi inches by 9 inches in 

 length, forward, 5 inches by 8 inches ; pillow-block caps for after journals 

 are 21 inches thick and Ih inches in width, and for forward journals 2^ 

 inches thick and (»i inches in width ; each cap held by two bolts 2^ 

 inches diameter; caps made so as to lip over ends of blocks. 



(] rank-shafts are of wrought iron, forged in one piece; after journals 

 (Ji by 9 inches, forward 5 by 18 inches, crank-pin journals 4f^ inches diam- 

 eter and Gi inches in length. 



Line-shafts are of wrought iron in three lengths, smallest diameter (i^ 

 inches ; covered with composition-sleeve the length of the stern-bear- 

 ing. Line-shaft couplings are of cast iron, turned and fitted and fast- 

 ened by six bolts 1^ inches diameter and with a steel feather. Coup- 

 lings of crankshaft to line-shaft are a ])air of cast-iron wheels, with 



