150 
REPORT—1854. 
of the apparatus invented by Mr. Fairbairn for submitting the substances to be 
operated on to the enormous pressure of 90,000 lbs. on the square inch. In these 
inquiries the objects kept in view were, to ascertain the exact laws which govern the 
cohesive strength of bodies in their present physical condition, and how far a know- 
ledge of those laws may conduce to the reduction of the* metals and their subsequent 
solidification under circumstances whereby increased strength and density may be 
obtained. The experiments commenced with spermaceti, bars of which were cast 
and left to solidify at the sume temperature, but under different pressures. When 
pressure was applied to these bars, the one that sustained u pressure of 40,793 lbs. 
carried 7*52 lbs. per square inch more weight than one submitted to a pressure of 
6421 lbs., the ratio being in favour of the more strongly compressed bar, in its power 
of resistance to a tensile strain, as 1 to ‘876. It appeared from these experiments, 
that bodies when solidified under pressure have not only their densities grratly 
increased, hut their molecular structure is also materially affected, so as to increase 
their adhesive power. Still further to elucidate the subject, cubeB of exactly one 
inch were cnrefully prepared and loaded with weights till they were crushed. The 
first cube, solidified under a pressure of 6421 lbs., was crushed with 213 lbs. Tm ww 
then operated on, a qunntity of pure tin being melted nnd then allowed to solidify! 
first at the pressure of the atmosphere, and afterwards at a pressure of 908 llw. on 
the square inch. The same quantity taken from the same ingot was subsequently 
submitted to a pressure of 5698 lbs. on the same inch. The bars, after being solidi¬ 
fied and allowed to cool for upwards of fourteen hours, were subjected to the u»ut 
tests of tensile strains. From these experiments there was derived, as nearly a* 
possible, the same law or measure of strength in regard to the effects of pressure M 
obtained from the experiments on spermaceti; for with the same pressures of 90S *• 
and 5698lbs. upon the square inch, the breaking weights were 4053lbs. and 5737 •- 
or in the ratio of 1 to '706, being an increase of nearly one-third on the crystnlliioi 
metal when solidified under about six times the pressure. From these facta Mr. 
Fairbairn observed, it is evident that the power of bodies to resist strain is Kf fnll 7 
increased when solidified under pressure ; and he said he considered it highly 
bable that the time is not fur distant when the resisting powers of metals, as w 
a- their densities, may be increased to such an extent as to ensure not only 
security, but greater (economy by solidification under pressure. Ho said h* . 
borne out in these views by the fact, that the specific gravities of the bodies experi¬ 
mented on were increased in a given ratio to the pressure. Spermaceti solidin 
under a pressure of 908lbs. on the square inch hurl a specific gravity of 0-9HW* 
whilst that solidified under a pressure of 5698 lbs. had its specific gravity increwru 
to 0 95495. The specific gravity of tin, solidified under a pressure of 908 lbs-, 
”'3063; and that solidified under a pressure of 5698 lbs. was 7‘3154, wine g 
•0091 as the increased density from pressure. There arc further experiment* 
progress to determine the law that governs this increase of specific gravity, ana 
determine the conducting powers of bodies solidified under severe pressure, ^xp' 
nments have also been made on such substances as clay, charcoal, and dine 
kinds of timber. I'rom the experiments on powdered dry clay, it appeared 
Ur of that substance 3* inches long and 1} inch diameter, after being bommataw ^ 
the cylinder, so as to become slightly consolidated, was reduced m bulk wit 
pressure of 9940 lbs. on the square inch to 2 958 ; with a pressure of o*.J ” . 
to 2’3; with 76,084 lbs. to 2'288; and with a pressure of 97*588 lhs. to 2 19 J 1 
Mr. Omox exhibited the model of a machine intended to prevent accident^ 
mines. This contrivance consists in having a spiral inclined plane passing 
the outside of the perpendicular shaft of a mine, by which plane the n,,n *T' 
ascend and descend without the necessity of being lowered in baskets down 
On Cunningham'* Plan for Reefing Topsails. By J. Grantham, CS 
This plan consist* of an arrangement by which the yard-arm ' 5 ma ^L 0 fibe 
round as it is lowered by a pulley fixed to the mast, and the slit in the centre j# 
ki.I through which the rope passes, to effect that movement of the vara- a 
dosed by a sail-cloth valve that preserves the action of the sail intact. 
