Depth to rabbet of keel 3 ft. 11¾ in.
Displacement (to two feet above rabbet of keel) 5.96 tons.
Weight of hull and fittings 4,675 lb.
" engine 1,240 "
" boiler 3,112 "
" water in boiler and tanks 2,696 "

The engine has a single cylinder 8 in. in diameter and 8 in. stroke of
piston. The screw is four bladed, 4 in. long and 31 in. in diameter by 45
in. pitch. The following is the performance at draught of water 2 feet
above rabbet of keel:

Boiler pressure 90 lb.
Revolutions 353
Speed 7.8 knots.
Indicated horse power. 53

These boats are of 1870 type, but may be taken as typical of a large
number of steam cutters in the United States navy. The naval authorities
have, however, been lately engaged in extensive experiments with compound
condensing engines in small boats, and the results have proved so
conclusively the advantages of the latter system that it will doubtless be
largely adopted in future.--_Engineer._

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IMPROVED STEAM TRAP.