o dampen and put out the fire as well as to make an alarm. They
may also be employed on other forms of boilers, and are much used in
connection with whistles for low-water alarms only. Boilers should not
be blown out for cleaning with fire under them or while the walls
(if set in brick) are hot enough to do damage to the iron shell.
Locomotive boilers may be blown out very soon after the fire is
entirely removed. All brick-set boilers should be left several hours
after the fire is drawn before blowing off for cleaning.

How to Lace a Quarter Turn Belt so as to Have an Equal Strain on Both
Edges of the Belt.--Begin on the outside of the belt at the middle,
pass one end of the lacing through one end of the belt and bring
it out through the corresponding hole of the other end of the belt,
laying it diagonally off to the left. Now pass the other end of the
lacing through the hole last used, and carry it over the first strand
of the lacing on the inside of the belt, passing it through the first
hole used, and lay it diagonally off to the right. Now proceed to pass
the lacing through the holes of the belt in a zigzag course, leaving
all the strands inside the belt parallel with the belt, and all the
strands outside the belt oblique. Pass the lace twice through the
holes nearest the edge of the belt, then return the lace in the
reverse order toward the center of the belt, so as to cross all the
oblique strands, and make all the inside strands double. Finally
pass the end of the lacing through the first hole used, then outward
through an awl hole, then hammering it down to cause it to hold. The
left side is to be laced in a similar way.

A Useful Hint to Draughtsmen.--To strain drawing paper on a board, cut
the paper to the size required, lay it on the board face downwards and
thoroughly wet the surface with a damp sponge or brush, then turn it
over and wet the face in the same way; roll it up tightly and let
it stay so for five or six minutes, unroll it, and turn up the edges
about an inch all around. Take liquid glue (Jackson's is the best) and
apply it carefully to the edges, then turn them down, and with a paper
knife press them to the board all around. Put the board in an inclined
position where it is not too dry or warm, or the paper will dry too
fast and tear. If it is allowed to dry slowly the surface will be
perfectly even and smooth, and a pleasure to draw upon.

Joints for Hot Water Pipes.--Sal-ammoniac, 2 oz.; sub