New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1856-10-20
INTESTINAL AND SCIENTIFIC INTEL
LIGENCE.

p,-.,-,v ~ r,prD CuSPowDER.-Itis well un-
ders,ood that the pressure Of the explosion IN gun
greatest at tie beginning and gradually dies away aS
the ball moves forward but this depends iucn y" '''
combustibitv Of the powder. With good qu'cA Po"
der the pressure at the instant the powder Is ut,u
in uense; but until recently no one has oeen ao'e !"
measure It. Dr. W. +. Woodbridge ana MaJoF Ai'''"
Mordeca have been recently making some eNPe'''
Irent THE expense ofthe Us. Ordnance Department.
for testing this point, at the Arsenal IN "aShins'ou'
With ball weighing about 81 Is and charge oil 10
Of Dupouts cannon powder. the greatest pressure Al
any instant the Interior of the gun at one men uom
the breech varied between 1900 and 2l,OOO POUNDS
per square irch. A. one foot from the breech the
greatest pressure was only about 5000 pounds at two
feet about the same at three feet about COCO. and at
four feet about 1900 pounds. The pressure Of small
quantity Of Hazards r6e powder, fred in cavity
ficm which there was absolutely escape, was not
sufficient to burst the box the strength Of which was
estimated sufficient to sustain an internal pressure OF
about $500 POUNDS per square inch These facts are
interesting they TO show how the metal should
be distributed in casting cannons and also to remove
Il belief which exists amsng practical men that
grain Of powder absolutely confined would exert an
il finite force.
CAST IRos TURSINGs.-It is common to consider
tie fine turungs, clippings and filings of iron nearly
quite valueess account Of their disposition TO blow
Up the chimney or stick and clog the drausht, st.
tempting to remelt them; but two methods have
been lately invented either Of which renders it per-
fctly practicable to remet these particles it,
usual there are considerable quantities of wrought
iron and dit inteminged. The first is by Dir. Abel
Pevey of Lowell, and consists in providing lot of
cheap hollow castings of any convenient form, and
filing them with the fine particles and placing them IN
the furnace, where the whole melts together. The
second ia BY Mr.. Edward Lyon Of this city, aud con-
ssts in merely pilng the fine particles in compact
mass as near possible to the center OF each charge
go that the draught may rise freely through the coal
around it. Both methods are successful in practice,
and patents we believe, are granted or pending Tor
each. The latter and obviously cheaper method Is
probably somewhat more wasteful of the metal than
the former, but the material is cheap and the Lyon
process may be generally preferred. Turnings are
valued, at many -hops at only 81 or 3 per tun, while
pig iron Of the same kind is worth $50.
Construction or WIRE CiBLES--It may be inter-
cstng to the inquirrg mind to know how the immense
cables which are employed to support suspension
bridges are manufactured and placed on the towers
which support them. They are made on the spot and
in the place they to occupy. There is no TWIST IN
tie strands but each wire is stretched across inde.
rendently and laid by the side of the others, after
which the whole is bound together by small wires at
intervals Of every few inches. The four cables which
support the bridge at Niagra are each some twelve OF
tLirteen inches in chamberlain too heavy to ot
handled as whole by any ordinary or extraordinary
tackle; but being laid with each wire pulling indie
rendently and each carefully stretched at the outset
80 A. TO correspond with the Others the whole difficulty
is sunounted and the fullest possible strength of each
wire is awaited Of.
RAILROAD ExpERIMEsTs.-It has been suggested
that as experiments in improved rail-, brakes, &C
when thoroughly conducted are quite expensive, ant
the results. ii published, benefit all roads alike, fun'
| should be raised by the Companies in united ca
| pacity TO pay for the same. 1t il good idea.