[9] CONSTRUCTION AND WORK OF FISH-HAWK. H 



interior, to tabes, and to all valves. The condenser is fitted with hori- 

 zontal yellow metal tubes | inch diameter, turned both inside and out- 

 side: cast-iron tube sheets 1^ inches thick, planed, and tubes i)ackcd 

 with '' Allen's" wood packing. Condensing surface is 900 square leet. 

 The tubes are arranged in three nests, and the condensing water passes 

 three times through the tubes. A 3i-iuch copper i)ipe is also fitted to 

 convert this into ajet condenser, if necessary. There is a screw-valve 

 li inches diameter connecting the salt with the fresh water, as an ad- 

 ditional feed ; also a brass cock for introducing soda. A perforated cast- 

 iron scattering plate is fitted above the tubes, upon which the injection 

 water impinges. 



Exhaust connections. — Exhaust connections from the cylinders to the 

 condenser are so ari-anged as to be independent; one engine exhaust- 

 ing without interfering with the other. 



Steam-pipe connections. — The main steam-pii)e is a single copper pipe 

 from the boiler, with slip joint and double poppet throttle-valve o])er-'.' 

 ated by a hand -lever. The pipe branches near the engines, and there 

 is a throttle-valve for each engine, operated independently. 



Air-pumps are horizontal trunk-]dunger pumps, one for each engine, 

 and driven by a crank upon the forward end of main shaft. Pumps are 

 11 inches diameter and 12 inches stroke; lined with composition; trunk, 

 piston, valve-seats, steins, and guards of composition; valves of ])ure 

 rubber; chests for receiviug and delivery valves cast with the pumps 

 and with convenient openings for access to valves. There is also a guide 

 cast on for slipper side of trunk. 



Rot icell. — There is a suitable cast-iron hot well, common to both air- 

 pumps, with vapor-pipe from top and overflow-pipe to outside of ship, 

 with proper outboard ^•alve. This pipe is of copper, 7 inches diameter, 

 No. 10 wire gauge ; composition valve 7| inches diameter, with compo- 

 sition seat and stem. 



Circulating pump is an independent steam-pump, direct acting, of the' 

 ^'Davidson'' pattern, 13^ inches diameter and 13 inches stroke; lined 

 with composition; piston, valve-seats, stems, and guards of same metal; 

 steam cylinder same diameter as pump; pump-valves of rubber. Out- 

 board delivery pipe is of copper, iSTo. 12 wire gauge, and fitted with out- 

 board valve of composition. To suction-jnpe there is a branch leading 

 to engine-room bilge, with a separate screw-valve and "check" Aalve to 

 prevent flooding. Screw-valve has an attachment for locking. 



Pistons are of cast iron, double shell, ribbed, with cast-iron follower 

 fastened by wrought-iron bolts screwed into brass bushings ; follower 

 turned and scraped to rings and piston, and fitted with eye-bolts for 

 lifting. Packing-rings of cast iron in two thicknesses, accurately turned 

 and fitted and set out with steel springs. 



Fi.ston rods are of mild steel, 2| inches in diameter, and fastened to 

 piston with a nut. 



Feed-pumps. — To each engine there is fitted a feed-pump, worked from 



