Se eS ee es  ——— a 
«| fl 
TRANSACTIONS OF SECTION G. 947 
and rear rollers, and has an actual centre pivot. The recoil is controlled by a 
single Vavasseur recoil cylinder placed in the centre of the slide, and giving a 
constant length of recoil for all charges, so that the spring catch to retain the gun 
at extreme recoil for loading is always reached. 
Torun out after loading, the spring catch is released, and the incline of the 
slide is sufficient to cause the gun to run out, which it does smartly, but is checked 
and brought to rest quietly by means of a controlling ram placed at the end of the 
recoil press. 
But I must conclude. I trust I have said enough to satisfy you as to the 
indebtedness of the naval and military services to mechanicians and to mechanical 
science, but you will also understand that within the limits of an address it is 
impossible to give a complete survey of so large a subject, and that there are 
important fields I have left wholly untouched. 
The following Papers were read :— 
1. A Hydraulic Steam Lifeboat, By J. F. Greuy. 
The author pointed out that, had it not been for the perfection now reached 
in the manufacture of mild steel and the invention of forced draught, the appli- 
cation of steam to the propulsion of a lifeboat would have been impracticable. 
The boat described in this paper has recently been built by Messrs. Green, of 
Blackwall, for the National Lifeboat Association, and is stationed at Harwich. 
Her principal dimensions are as follows: Length, 50 ft, Beam, moulded, 12 ft. 
Extreme breadth, 14 ft. 8fin. Draft, when fully loaded, 3 ft. 6in. Displacement, 
when fully loaded, 26 tons. Speed, when fully loaded, 9°367 knots. Indicated 
horse-power, 170. 
The author, after explaining why it was impossible to adopt either the paddle- 
wheel or the screw as a means of propulsion, gave the following reasons in favour 
of the hydraulic system, adding that the actual trials have fully justified its 
adoption. 
% The propelling power is instantaneous, and-as efficient in a heavy sea as in 
smooth water. 
2. No racing, loss of power, or injurious effects to the machinery in a rough 
sea. 
38. No vibration such as is caused by a screw or paddle-wheel. 
4. The engine only running in one direction, there is no excessive wear of 
machinery, or loss of time due to stoppage and reversal. 
5. The management of the vessel is in the hands of the officer on deck. 
6. No obstacles under water to interfere with sailing. 
7. When the rudder is damaged, steering can be effected by the turbine. 
The vessel is divided into 15 water-tight compartments and possesses ex- 
ceptional stability, righting herself up to an angle of 110°, and on trial the 
manceuvring power was not less satisfactory. A number of interesting experi- 
ments which had keen made with a view to ascertain the behaviour of the boat in 
ine eens of wreckage were also described ; their results were all that could be 
esired. 
The propelling machinery has been constructed by Messrs. Thorneycroft, of 
Chiswick, the engines being of the horizontal compound surface-condensing type, 
with cylinders 8} in. x 143 in., and 12 in. stroke. The paper gave details of the 
boilers, fan engine, turbine, &c., and it may be added that this turbine delivers 
ey through the outlets at the rate of 1 ton per second; the sailing power is 
ood. 
3 The well accommodates 30 passengers and is abaft the machinery, Under its 
deck are two watez-tanks, which are filled when leaving for a wreck, being emptied 
when passengers are taken on board. 
The consumption of coal, even under forced draught, is small, averaging 2 cwt. 
per hour, so that the bunkers hold a sufficient supply for 30 hours. 
