of Edinburgh, Session 1865 - 66 . 507 
round the core, which latter is padded with ordinary hemp, satu- 
rated with preservative mixture. 
Circumference of Finished Cable, 3*534 inches. 
Weight in Air, 35 cwt. 3 qrs. per nautical mile. 
Weight in Water, 14 cwt. per nautical mile. 
Breaking Strain, 7 tons 15 cwt., or equal to eleven times the 
cable’s weight in water per mile. Hence the cable will bear its 
own weight in eleven miles depth of water, or 4*64 times the— ^ 
Deepest Water to be encountered, 2400 fathoms, or less than 
nautical miles. 
Length of Cable Shipped, 2300 nautical miles. 
II. 
Let W be the weight of the cable per unit of its length in water ; 
T the force with which the cable is held back at the point where 
it reaches the water (which may be practically regarded as equal 
to the force with which its egress from the ship is resisted by the 
paying-out machinery, the difference amounting only to the weight 
in air of a piece of cable equal in length to the height of the stern 
pulley above the water) ; P and Q the transverse and longitudinal 
components of the force of frictional resistance experienced by the 
cable in passing through the water from surface to bottom ; i the 
inclination of its line to the horizon ; D the depth of the water. 
The whole length of cable from surface to bottom will be . : 
® sin ^ ’ 
and the transverse and longitudinal components of the weight of 
this portion are therefore h WD respectively. These 
are balanced by P — •- and T + Q — :• 
sin ^ sin ^ _ 
Hence 
P = W cos^'j Q=^W - sin^’ (1.) 
To find the corresponding components of the velocity of the 
cable through the water, which we shall denote by p and q, we 
have only to remark that the actual velocity of any portion of the 
cable in the water may be regarded as the resultant of two veloci- 
