448 POPULAR LECTURES AND ADDRESSES. 



free from tension ; but if it is not on the bottom, D 

 must denote its vertical depth at any moment, 

 instead of the whole depth of the sea. To apply 

 to the case of merely towing, we must put u = o ; 

 or, to apply to hauling in, we must suppose u 

 negative. 



It is to be remarked that the inclination assumed 

 by the cable under water does not depend on its 

 longitudinal slip through the water (since we 

 assume this not to influence the transverse com- 

 ponent of fluid friction), and that, according to 

 equation (4), it is simply determined by the ratio 

 of the ship's speed to the transverse " settling 

 velocity" of the cable. 



The following table shows the ratio of the ship's 

 speed to the " transverse settling velocity " of the 

 cable for various degrees of inclination of the cable 

 to the horizon : 



