426 POPULAR LECTURES AND ADDRESSES. 



triangle, of which the two equal sides are the 

 inclined portion of the cable between it and the 

 bottom, and the line along the bottom which this 

 portion of the cable covers when laid. When the 

 cable is paid out from the ship at a rate exceeding 

 that of the ship's progress, the velocity and direc- 

 tion of the motion of any particle of it through the 

 water are to be found by compounding a velocity 

 along the inclined side, equal to this excess, with 

 the velocity already determined, along the base of 

 the isosceles triangle. 



The angle between the equal sides of the isos- 

 celes triangle, that is to say, the inclination which 

 the cable takes in the water, is determined by the 

 condition, that the transverse component of the 

 cable's weight in water is equal to the transverse 

 component of the resistance of the water to its 

 motion. Its tension where it enters the water is 

 equal to the longitudinal component of the weight 

 (or, which is the same, the whole weight of a length 

 of cable hanging vertically down to the bottom), 

 diminished by the longitudinal component of the 

 fluid resistance. In the laying of the Atlantic 



