SCIENTIFIC SUMMARY. 503 
times its own depth, was sensibly more than double its resistance when half 
immersed. 
In the discussion which followed the reading of this report, Mr. Bailey and 
Admiral Belcher haying spoken with disapproval of hollow lines or wave- 
lines at the bows of sea-going vessels, Professor Rankine pointed out, that 
the wave-line theory consisted of two branches, one relating to the form of 
the bows, the other to the relation between the length of the vessel and the 
speed at which she was to be propelled through the water. He did not 
attach much weight to the hollow bow, but thought that much was to be said 
in favour of the theory that the length should have a certain relation to the 
speed. 
Friction of Steam in Cylinders. — Professor Rankine communicated a paper, 
in which he pointed out that the loss of power caused by the friction of 
steam is compensated by the heat generated by the friction, the work done 
and the heat expended being both diminished by the same quantity ; the 
heat generated tending to prevent liquefaction in the cylinder. 
Penetration of Projectiles. — Captain W. H. Noble, R.A., read a voluminous 
paper on the penetration of projectiles, containing the results of a series of 
experiments lately carried out by him, under the direction of the Ordnance 
Select Committee. The conclusions arrived at may be summed up as 
follows : — 1st. Where it is required to perforate armour-plate the shot should 
be of steel or chilled iron, the latter being nearly as effective as the former in 
the case of solid shot. 2nd. The form of head best suited to the perforation 
of plates is the pointed ogival. 3rd. To attack ironclads effectively the guns 
should be at least twelve tons weight and nine inches calibre, firing an elongated 
projectile of 250 lb. with about 40 lb. of powder. 4th. When the shot is 
of hard material the power of perforation is directly proportional to its vis 
viva , and universally proportional to its diameter. 5th. The resistance of 
wrought-iron plates to perforation by steel projectiles varies as the square of 
their thickness. 6th. Striking a plate obliquely diminished the power of 
penetration in the proportion of the size of the angle of incidence. 7th. The 
resistance of wrought-iron plates is very little, if at all, increased by a back- 
ing of wood, but is much increased by a rigid backing of iron and wood com- 
bined, or other suitable material. 8th. Iron-built ships with wood backing 
offer more resistance than iron-clad wooden ships. 9th. The best form of 
backing seems to be that in which the wood is combined with horizontal 
plates of iron. 
The formula arrived at by Captain Noble is similar in form to that pub- 
lished by Dr. Fairbairn, and is essentially different from one recently pro- 
posed on theoretical grounds by Dr. Rankine. 
Tunnel under the English Channel. — Mr. Hawkshaw is engaged in making 
trial borings with a view to develope a project for a railway tunnel under the 
Channel between Dover and Calais, and communicating on the English side 
with the Chatham and Dover Railway, and on the French side with the 
Northern of France Railway. He proposes to carry on the excavations for 
the tunnel from both ends, and also from shafts in the Channel, at the top of 
which powerful engines will be erected for pumping and winding up the ex- 
cavated material, and for supplying motive power to the machinery by 
which the excavation is effected. — “ Y. v in the Times. 
