The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-03-01

ling it being thus described First the greater 70
cllty with which the two images apparently coaI
escc second, less fatigue to the observer the tran
parent and Opaque picture being viewed in ill.,,
same place, and the best part viz the central nor
ton ct the lens is only used: the pictures are I.r
fore seen much more perfectly than in the ordinary
form OF instrument with two small semi-lenses IN;
closea IN orass or ivory cyepeices. Another mark
ed advantage Is perfect adjustment of focus to DIFF
terent sights. The lens-whlch is an ordinary plano
convex cut IN halves, and the tw edges turned
round so as to form the centre-is mounted in a su-
periof manner to the common form of stareoscopa
hehecteu hght, either from lamp or window, is di-
rected on the Opaque pictures: transmitted Epbt
through the transparent
TESTING THE STRENGTH or MArERrAs.-An an
Pafat4S mas been invented by Mr. Lowthnrp. of
New Jersey, Tor testing the strength of materials
ana mas been patented in England France Raj
gum ana TINS country The machine is DESIGNED
Tor ascertalnlng the amount of tensile and trans
verse strand torsion crushing effect which ma
terlals are capable of withstanding. and consists in
so combining suitable gearing and other mecban-
ism for applying the strains or forces with a netan
or plunger, operating against a BODY of water or
other mud within a cydner or barrel that on an
plying the force or strain to the object to be tested
/ by means OF the gearing such pressure shall be
transmitted to the fluid in the cylinder or barrel
and to any suitable indicating apparatus in oonnac
tlon with the same as to enable the attendant to
readily calculate the amount of strain or force to
which the object has been submitted
/ STRENGTHENING ELECTRO-MAGNETs- Scbaizil,
engineer OF the imperial teegraphs of Austria has
endeayored to remedy the inconvenience arising
from the considerable diameter of the conner wire
with winch the core of iron has hitherto been
wrapped, when powerful electromagnetic effects
were to be obtained. He has perfectly succeeded
by wrapping the core with ribbons of copper, pre-
sentng their edges to the This new apparatus
IS said to occupy much less space than an apparatus
with thick cores and produces powerful effects by
means OF galvanic current, developed by a battery
OF few lev, but large elements. Professor Henry Of
ashlngton, the first use ribbons in place OF
wires, Tor wrapping trO-magnets, but his coils
were laid fiat Whether the new plan possesses
essential superiority that of Prof Henry is point
as yet undetermined.
IMPROVEMENT N MINING LAMPs.-Mr. Sherwood
OF Birmingham, England has brought ont a lamp
Tor use IN mines, having glass chimney in the in
SIDE OF wire gauze and a fat wick, with a pecu-
mar burning apparatus, differing materially from
that adopted in any of the lamps employed in
mines. The wick takes up by capillary attraction.
llght OIL, and passes through tattened tube
where 1t Is capped with brass nozzle. having a
long sht IN the top, and plenty of airholes in the
SIDES w hen the wick Is lighted a great current OF
an imPinges on the flame, as it passes through the
Slt IN the nozzle, and thus insures a perfect com
Dustlon, such as has not hitherto been effected in
any other mining lamp. The light makes little o,
no smoke, and requires no snuifing for twenty-fou
hours and it can be raised up and down by an ad
Justng screw, in simple and effective manner
NENEERiNG BY TRANSFER.-A process of veneerins
by transfer Is mentioned with approval in tn,
french journals; The sheet of vencering or inlay
ing to be copied is to be exposed for few minutes
to the vapor of hydrochloric acid This novel platt
Is then iaid upon calico or paper, and impression
struck of with printing press. Heat is to be ap
Piled Immediately after the sheet is printed when
perfect impression of all the marks. figures ant
convoluted lines of the is said to be instanta
neously produced. The process, it is affirmed ma,
De repeated Tor an almost indefinite number of times
Inc designs thus produced are also said to eyhibi
! a general wood-like tint most natural when oak
walnut maple. and the light colored woods hav