[47] U. S. FISH COMMISSION STEAMER ALBATROSS. 49 



similar to that employed on the distributing roller of the Adams print- 

 ing press ; this screw reverses the direction of the guide when it reaches 

 the end of the thread, and the pitch of that thread is equal to the 

 diameter of the rope. • It is geared to the drum by toothed gears of 

 equal pitch diameters, one of which has a clutch coupling for disengag- 

 ing. When paying out rope the guide is disengaged not only from the 

 toothed gears, but also from the double screw, which leaves it free to 

 travel by the pressure of the wire rope upon its sides. 



The principal dimensions and the weight of the reeling engine and 

 wire rope are as follow : 



Diameter of the dram inches. . 16 



Length of the drum do '.i6 



Width of the flanges do 17 



Ratio of the gearing 4-i% : 1 



Number of steam cylinders 2 



Diameter of the steam cylinders - inches.. 7^ 



Stroke of the pistons '. do 8 



Length of f -inch diameter wire rope the reel will hold fathoms . . 4, 500 



Weight of the reeling engine pounds. . 3, .500 



Weight of the 4,500 fathoms of wire rope .• do.... 5,940 



Total weight of the engine and wire rope do 9, 440 



The engine receives steam from the main boilers and exhausts it 

 into the main condenser or into the atmosphere as desired. 



The wire rope, after leaving the dredging engine, is passed under a 

 governor, a (Plate XXV), then to a leading block forward of the engine, 

 and finally back to the reeling engine. The object of the governor is 

 to keep a tolerably uniform tension on the rope, compensating for the 

 surging on the dredging engine, and at the same time accommodating 

 the plane of its sheaves' rotation to the varying direction of the wire 

 rope as it passes. This governor is the invention of Lieutenant-Com- 

 mander Tanner, the writer being responsible for its proportions. It 

 consists of a sheave revolving in a vertical j)lane, within a frame which 

 moves on a horizontal axis ; the pressure on the sheave being resisted 

 by a spiral spring shown in Plate XXV. To augment the efficiency of 

 the governor ihe writer added the bell-crank and rod (b) to operate a 

 Watson & McDaniel pressure-regulating valve, instead of the throttle 

 as was originally intended. By this simple arrangement the tension 

 on the wire between the dredging engine and the reeling engine controls 

 the motion of the latter. The pressure regulator is automatic, indepen- 

 dently of the motion of the engine, and is, therefore, an additional 

 safety ; it is similar to the valve shown in Fig. 18, but has a lever and 

 weight instead of a spring as shown in that figure. 



SOUNDING ENGINE. 



The soundijig engine (Plate XXVII) was built by Copeland & Bacon, 

 of New "iiOrk, according to the design and safe patent of Mr. E. C. 

 Bacon., It is a single- cylindered, vertical, half-trunk engine with U; lo-_ 

 H. Mis. ajJ— 4 



