496 POPULAR LECTURES AND ADDRESSES. 



the Froudes, father and son, and by practical men 

 like the Dennys, W. H. White, and others ; who 

 have taken up the science and worked it out in 

 practice. But there is one suggestion founded on 

 the doctrine of wave-making, which I venture to 

 offer before I stop. I have not explained how 

 much of the resistance encountered by a ship in 

 motion is due to wave-making, and how much to 

 what is called skin resistance. I can briefly give 

 you a few figures on this point, which have been 

 communicated to me by Mr. Edmund Froude. 

 Fora ship A, 300 feet long and 3I-J feet beam and 

 2634 tons displacement, a ship of the ocean mail 

 steamer type, going at 13 knots an hour, the skin 

 resistance is 5 '8 tons, and the wave resistance 3*2 

 tons, making a total of 9 tons. At 14 knots the 

 skin resistance is but little increased, namely 6'6 

 tons; while the wave resistance is nearly double, 

 namely 6' 15 tons. Mark how great, relatively to 

 the skin resistance, is the wave resistance at the 

 moderate speed of 14 knots for a ship of this size 

 and of 2634 tons weight or displacement. In the 

 case of another ship B, 300 feet long and 46*3 feet 



