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TRANSACTIONS OF THE SECTIONS. 215 
leakage. In order to obviate this difficulty, the wire is coated with gutta percha by 
means of rollers mounted on parallel axes, and revolving in contact with each other. 
Each of these rollers is grooved in its periphery, and these grooves meet to form an 
eye, the sizes of the covering desired. Against these rollers are placed hoppers, in 
which gutta percha or Indian rubber is placed, in the state in which it comes from 
the masticator. This Indian rubber or gutta percha enters and fills yp the grooves 
of the rollers; and where they come together, the gutta percha or India rubber in the 
grooves is brought together in one piece enclosing the conducting wire. The longi- 
tudinal strength and obtension are obtained hy imbedding fibres of hemp, flax, or 
cotton in an outer layer of insulating material; this is done with great pressure. 
The covering is subsequently subjected to treatment which enables it to resist tropical 
heat, and affords quite sufficient protection against ill usage. The shore ends of the 
cable, or for shallow water, are protected with strong wire. In place of sulphuric 
acid, Mr. Mackintosh recommends the use of chloride of sulphur, mixed with a sol- 
vent by sulphuret of carbon. Add to this from 2 to 4 per cent. of chloride of sul- 
phur, and then pass the wire through it. The speed at which the covered wire 
passes through the liquid is so regulated as to allow of its remaining therein for 
about three seconds, and this process closes up the pores thoroughly, and renders 
the wire much less likely to be injured by heat or abrasion. The method of sub- 
merging cables prepared by the author was to pass them through an apparatus con- 
taining water and hard-wood balls, which would allow of the accomplishment of the 
work without injuring the electrical condition of the ropes. 
On the Submersion of Electric Cables. By J. MACLEAN. 
The author proposes a plan stated to possess the following advantages :— 
1. That any amount of slackable cable, from a few feet to several hundred feet, 
might be obtained by adopting the plan proposed, so as to meet the pitching of the 
vessel in a heavy sea, or any sudden stoppage in the paying-out machinery. 
2. By conducting a lever, upon which the spiral springs impinge, to the paying- 
out machine, the rate at which the cable ought to be paid-out might be self- 
regulated. : 
3. Or this lever might have an indicator such as a dial-plate, by which the person 
who superintends the paying-out machine could see that a strain is upon the cable, 
and that more is instantly wanted ;—the slackable cable in the apparatus giving him 
time to accelerate his machine, before the strain reaches a fixed point. 
4. The plan might be wrought nearly as well with the apparatus lying in a hori- 
zontal position,—of course allowing the compensation weights to work perpen- 
dicularly. 
5. The strain upon a cabie, equal to one ton each mile, could never, under 
ordinary circumstances, by the plan proposed, exceed 3000 lbs., which is only one 
half of the strain caused by the pitching of the vessel during the late experiments in 
the Bay of Biscay. 
6. By passing the cable under and over grooved wheels, an amount of friction 
would be created, which might be an advantage rather than a disadvantage ; because, 
in the late experiment, it was found that the cable ran too swiftly, and that it was 
necessary toapply breaks. By adopting the plan described above, the increasing and 
decreasing friction, according to the amount of strain, would act as a self-regulating 
break. 
On the Performance of Steam Vessels, the Functions of the Screw, and the 
Relations of its Diameter and Pitch to the form of the Vessel. By Vice- 
Admiral Moorsom. 
The author proposed to furnish the Association with such further information on 
the performance of vessels at the measured mile as may induce them to appoint a 
Committee with the specific object of procuring experiments to be made at sea, the 
records of which shall be kept in such form as will enable competent persons to 
calculate from them the characteristics of vessels’ engines and screw propellers, so 
that the performance of each may be duly apportioned. 
