490 POPULAR LECTURES AND ADDRESSES. 



while it was obvious from the waves it made that 

 it was not going more than 12. In Fig. 7 we have 

 wave profiles for another ship at two different 

 speeds. The upper line corresponds to a speed 

 of 1 8*4 knots ; the lower line to a speed of 17 

 knots. In the first case the water shoots up to 

 its first maximum height close to the bow, sinks 

 to a minimum towards midships, and flows away 

 past the stern slightly above still-water level. In 

 the second case the character of the wave is some- 

 what similar, but smaller in height ; and there is a 

 marked difference at the stern, due to other dis- 

 turbing causes. In Fig. 8 we have three different 

 speeds for H.M.S. Orlando similarly represented. 



There is still another very interesting series of 

 diagrams, Figs. 13 to 19, Plates 83 and 84, taken 

 from Mr. Edmund Froude's paper " On the Lead- 

 ing Phenomena of the Wave-making Resistance 

 of Ships," read before the Institution of Naval 

 Architects, 8th April, 1881. In Figs. 13 to 17 

 are shown the waves produced by a torpedo 

 launch at speeds of 9, 12, 15, 18, and 21 knots per 

 hour. We need not here go into the law of wave- 



