The true northerner., 1882-04-28
THE WORKSHOP.

THERE have been proposed circular
saws made of three layers, each side cast
steel and the middle tough wrought
iron.
A NEW slate frame is made from strips
of pasteboard, hard felting. or the like,
nodded and cemented together, and
which is designed to obviate the disa-
greeable noise made by pupils in using
the ordinary wooden frame.
To GET gear wheel off a shaft upon
which it has been shrunk it is recon-
mended to pour some melted iron around
the hub, by which operation tho latter
will expand 50 quickly that there will be
no time for the shaft to get hot, and the
gear will come off easily.
SUTTON says that he improved high
priced modern circular saw by removing
about three-fourths of the teeth, leaving
three times the usual space between the
remainder this would give more than
three times the usual space. Mr.. Sutton
considers that eight teeth is enough for
saw five feet in diameter.
The "Woodpecker" saw, worked at
an early period in saving large logs in
California, was a considerable length of
a common straight saw. with hole in
the center, and mounted on shaft so as
to rotate in the same manner rs the cir
cular saw. 1t had only two teeth, one
at each end. II required plenty Of
power.
A NOVELTY in the utilization of wire
fences consists in insulating one of the
continuous wires, and connecting its
ends with the opposite poles of bat
terry. Animals coming in contact with
this wire will receive n shock from the
electric current, which will effectually
deter them, it is said, from attempting
to break down or override fences of this
description.
ONE Of the hardest woods in existence
is that of the desert ironwood tree,
which grows in the dry washes along the
line OF the Southern Pacific Railroad.
Its specific gravity is nearly the same as
that OF lignumvit@, and it has black
heart so hard, when we'll seasoned, that
it will turn the edge of an ax, and can
scarcely be cut by well-tempered saw.
In burning it gives ont an intense heat,
and charcoal made from it is of une-
qualed quality.
a NEW and efficient process of manu-
featuring paper from straw consists in
first cooking the straw, then reducing it
to pulp, whereby the fiber is disinteg-
rated, but not destroyed, and all the
gluten and albumen of the straw is re-
tained, and finally bleaching it in ves-
sci OF novel construction. which obviates
the introduction therein of any solid
particles of alkali 1t is said this pro-
cess renders the paper tough and plia-
bic. 1t is asserted, also, that tins paper
treated with glycerine assumes the con-
sistency of leather.
MI. JOSHUA ROSE, well-known me-
chanical writer, explains that the tend
ency OF nut TO unwind aud recede from
the pressure upon its radial face is pro-
portonate to the pitch of the thread and
the diameter OF the bolt ; and the finer
the thread upon Il given diameter of bolt,
or the larger the diameter of bolt with "a
given pitch of thread, the less will be
the tendency of the nut to move back.
In the case of ordinary bolts and nuts, a
given diameter of bolt is given stand
ard pitch of thread, and these pitches
are not SO fine as to prevent the nuts
from unscrewing IN many cases, unless
check nuts are used. 1t would be other.
wise if the nut thread fitted reasonably
tight upon the bolt for if the nut is
screwed we'll home it should remain
there.