The daily exchange. [volume] (Baltimore, Md.) 1858-1861, 1858-03-01
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NOTES on THE PROGRESS OF SCIENCE

/ PHoToGRAPHING DRAWINGS ON WOoD.-M. Lalle-
mand is the author of a process for phOtograrhing
drawings upon the wood which it is to be en-
grayed in relief. The wood is first placed with its
surface on solution of alum, and dried it then re-
ceives with soft brush a coating composed of ami
nal soap, gelatine and alum upon all its faces
When the coating is dry, the surface which re-
ceive the picture Is placed for minutes i'll
luton of sal-ammoniac then dried; afterwards on
bath of nitrate of silver of 20 per cent, and then
dried \ cliche upon glass paper is then applied
on the wood by means of peculiar frame, permit
ting the process of the reproduction to be matched
when satisfactory the picture is fixed by of
saturated bath of hyposulphite of Soda few min
utes being enough-and it is then washed for only
/ five minutes. The first coating preserves the wood
from moisture; and eight months Of experience have
1 proved that the employment of anm and hypo-
sulphte, in place of destroying the wood, gives it
great strength, which is peculiarly favorable to the
engraving.
| CAST Iron PILLARS. - Profess9 Hodgknson. of
London, has shown that long circular pillar, with
/ its ends fat, is about three times strong as
pillar of the same length and diameter with its ends
/ rounded in such manner that the pressure will
pass through its axis, the ends being made to turn
! easily, but not small as to be crushed by the
weight also, that if pillar of the same length and
diameter as the preceding have one end rounded
and one fiat, the strength will be twice great
that OF one with both ends rounded. Consequently,
if three pillars be taken. differing only in the form
! of their ends the first having both ends rounded,
the second with one end rounded and one end fiat,
these different pillars will be found to be nearly
one two, three.
IMPROVED RAILROAD FRoG.-This device is of the
ordinary form, of castron with steel point and
steeled iron tread plates-the peculiarties consist
ing in the general shape of the parts of the frog
and in the arrangement of the point, by which it
can be easily removed and replaced, and fastened
very firmly to the place. The shape is well proper
toned combining all the most approved forms, and
carefully adapted TO the safe and easy passage of the
wheels. The steel point, instead of being rveted
to the plate in the ordinary wav is fitted into a
dovetailed groove in the plate, its wedgod form al
lowing it to be inserted at the wide part of the
groove and pushed up into the angle, square cast
iron block being dropped in behind it to keep it in
its place. The wide tread-p plate behind the point
being riveted on, keeps the whole firmly in place.
This arrangement is new and is found most effect
i've method of attaching the point to the casting
making it exceedingly firm and easy to remove for
| repairs
BAR IRoS.-Mr. W. Clay, of Liverpool, has pa
tented some Improvements which contemplate the
employment OF rolling pressure for the conversion
OF bar iron of various sectional figures such as plain
straight, square bars, channe-grooved, &C. into
tapering bars-the object being to import to bars of
iron so made different strengths or powers of re-
slstance at different points, and thereby to adapt
rolled metals to various uses when gaeater strength
or rigldlty Is required at point than another
Inc method also relates to the. adaptation of roll
ing pressure to the formation of baIs with sudden
inequalities of depth or thickness, forming projec
tons, protuberances, or indentatons, or in the
bars, at different points, according to the particular
purpose for which the iron is required. Instead of
allowing the top roll to rise gradually in its bear
ings, as heretofore the inventor adjusts the rolls to
the work they have to perform, and keeps them to
that position until the operation is cOmpleted-the
object being to produce class of work, the irregu
larity in the section of which is too great to permit
Of its being manufactured with facility by the
rising roll process
Thus, for forming a taper the extremity of
bars, suitable for railway points the rolls are
to a distance apart that will correspond with the
greatest depth which the formed bar is required to
measure, say three inches; and, assuming, also,
that the extremity of the bar is to be tapered down
to one inch in depth, plate of iron or steel of a
taper form is provided Of thickness corresponding
exactly with the diminution of thickness reouredin
the end of the bar under operation This plate is
taken in its cold state, and placed over the end of
the bar of redhot metal the two being then pressed
between the rolls. The taper plate, acting as fill
ing-piece or as an eccentric projection on one of
the rolls would act, enables the rolls to put sever
er pressure the bar at the part overlaid bv the
plate, and thus by simple rolling, in an ordinary
rolling mill, taper bar is produced
New STEREoscoPE.-A new stereoscope has been
manufactured by Messrs. BuRFIELD RoMB, of Lon
don, to which they have given the name of the Cos
morama Lens Stereoscope, the advantages character