The news and herald. (Winnsboro, S.C.) 1877-1900, 1879-10-02
SCIENTIFIC.

TIE SAND BtaSt.-AmOug the wonder
ful and useful Inventions Of the times
is the common sand blast. Suppose you
desire to letter II piece of marble for Il
grave stone; you cover the stone with
sheet Of wax no thicker than q wafer,
then cut in the wax the name, date, etc.,
leaving the marble exposed. Now pass
it under the blast, and tho wax will not
be injured ut all, but the sand will cut
letters deep into tho stone. Or, If you
desire raised letters, Il flower or other
emblem, cut the letters, flowers, ETC.,
in wax and stick them upon the stone;
then pass the stone under the blast, and
the wax will cut 1T away. Remove the
wax and you have the raised letters.
Take Il piece Of french plate glass, say
two feet by six, and cover with fine lace
pass 1T under the blast and not Il thrcad
of the lace will be injured, but the
wherever 1t is not covered by lace.
Now remove the lace, and you have
every delicate and beautiful figure
raised upon the glass. In this way
beautiful figures Of all kinds arc cut in
glass, and at Il small expense. The
w0rkmcn can hold their hands under
the blast without harm, even when 1t is
rapidly cutting away tho hardest glass,
iron or stone, but they must look out for
finger nails, for they will be whitfield
of right hastily. If they put on steel
thimblcs to protect the nails, it will do
little good, tor the sand will soon whit
Tie them away, but if they wrap piece
Of soft cotton around them they are safe.
You will at once sec the philosophy Of
1t. The sand whittles away and destroys
any hard substance, even glass, but does
not affect substances that arc soft and
yielding like wax, cotton or fine lace or
even the human hand.
The Writing MuGhinc.-'rhc mctalo-
graph is the name Of an Instrument Just
invented by II BostOnian, and is likely
to be of service to writer's. 1t can do
things that the electric pen cannot ac-
complisb. Its motive power is COM
pressed air instead of electricity. The
instrument is thus described: cit con-
sists of Il hardened steel point, which,
when in use, is mOvcd up and down,
within metal tube, very rapidly by
means of Il cam and spring. The cam
is on little metal shaft, which Is re-
volved by wheel, which is connected
by II rubber tube with Il pair of bellows
under Il table, and can be worked by
hand or foot. Resting the instrument
pcrpendlcularly upon thin sheet of
metal, and setting the bellows in motion,
4 person may write with it upon tho
metal, making what appears to be con-
tlnuous line, but really Il dotted line.
The letters made are embossed upon the
metal. The sheet Of metal is then to be
placed in Il small press and covered by
Il suitable piece of carbon paper, and
ovor that again the paper to be written
upon is placed. The press is then set
In motion and copies Of the writing or
composition can be produced very rap
idly. No liquid ink, acid or electricity
is used. The little machine can be used
In manifold writing. The mctalograph
will also be of service in signing bank
checks and other Important documents,
for 1t will be impossible to alter or erase
signatures made with it.
Specific CRAFTY Baiance.-M. Gannal
has recently DEVISED Il simple means of
determining the specific gravity of
liquids. With his dcnsimetre hyhro-
statiquc all calculation is obviatcd, and
the specific gravity Is ascertaincd by
simply reading the weight OH the bal
ancc. This apparatus is made in the
form of an olive, 80 that bubbles OF air
shall not attach themselves to its sides.
The olive of glass or metal has Il volume
exactly equal to one decimal subdivision
of Il cubic metre. There are two differ
cnt methods employed in the practical
use of the appatus. (D We may sus-
pend 1t on the platform Of the balance,
and having produced an equilibrium,
we plunge :. into tho liquid; the equi-
librium is then destroyed by the loss Of
weight of the olive, and the number of
grams which it is necessary to add to
the scale-pan to restore the equilibrium
is the exact specific gravity Of the liquid.
(2)Or the liquid whose specific gravity
we desire to ascertain may be put in 4
glass vessel on one pan of the balance;
balance the scale-pans, and then sus-
pend the olive in the liquid by means
of a fine thread. The equilibrium is &C.
stroycd, and the scale descends on the
side on which the olive is suspended,
and the weight, which it is necessary
to place in the other pan to restore the
equilibrium, is equal to the specific
rr Wit Of thn 1fnnil