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._

* * * * *

IMPROVED STEAM TRAP.

The illustrations we give represent an expansion trap by Mr. Hyde, and
made by Mr. S. Farron, Ashton-under-Lyne. The general appearance of this
arrangement is as in Fig. 1 or Fig. 3, the center view, Fig. 2, showing
what is the cardinal feature of the trap, viz., that it contains a
collector for silt, sand, or sediment which is not, as in most other
traps, carried out through the valve with the efflux of water. The escape
valve also is made very large, so that while the trap may be made short,
or, in other words, the expansion pipe may not be long, a tolerably large
area of outlet is obtained with the short lift due to the small movement
of the expansion pipe.

[Illustration: IMPROVED STEAM TRAP.]

The object of a steam trap is for the removal of water of condensation
without allowing the escape of steam from drying apparatus and steam pipes
used for heating, power, or other purposes. One of the plans employed is
by an expansion pipe having a valve fixed to its end, so that when the
pipe shortens from being cooler, due to the presence of the water, the
valve opens and allows the escape of the water until the steam comes to
the trap, which, being hotter, lengthens the pipe and closes the valve.
Now with this kind of trap, and, in fact, with any variety of trap, we
understand that it has been frequently the experience of the user to find
his contrivance inoperative because the silt or sand that may be