'30 ANNUAL OF SCIENTIFIC DISCOVERY. 



at sea, he would undertake to say that they would find she was constructed 

 on the wave principle. Mr. Robert M'Kay, the builder of the great Ameri- 

 can clipper, paid him a visit twelve months ago at Milhvall, to sec the big 

 ship, and he then very candidly said, "Mr. Russell, I have adopted the wave 

 principle in the construction of all my American clippers, and that is my 

 secret. I first found the account of the wave line in the publications of the 

 British Association." He would endeavor to explain what were the prin- 

 ciples of the wave line as distinguished from the older-fashioned modes of 

 building, and how they were carried out in the big ship. All practical men 

 knew that the first thing a ship-builder had to think of was what was called 

 the mid-ship section of the vessel, that was the section which would be 

 made if the ship were cut through the middle, and the spectator saw the cut 

 portions. Mr. Russell here pointed out a diagram of the mid-ship section 

 of the Wave, a small vessel about seven and a half tons burden, which was 

 the first ever constructed upon that principle. Xow, the first thing to be 

 done in building a steam-vessel was to make a calculation of the size of the 

 mid-ship section in the water. In sailing from one place to another, it was 

 necessary to excavate a canal out of the water large enough to allow the 

 whole body of the ship to pass through. The problem was how to do that 

 most economically, and this was effected by making the canal as narrow 



i/ y , 



and as shallow as possible, so that there would be the smallest quantity of 

 water possible to excavate. Therefore it was that the ship-builder endea- 

 vored to obtain as small a mid-ship section ar, he could, and that had been 

 effected in the case of the big ship, whose mid-ship section was small not 

 small absolutely, but small in proportion. In increasing the tonnage of a 

 ship, three things are to be considered the paying power, the propelling 

 power, and the dimensions. Mr. Russell then entered into a calculation to 

 show that while he doubled the money-earning power of a ship by increasing- 

 its size, he only increased its mid-ship section by fifty per cent. For in- 

 stance, a ship of twenty-five hundred tons would have five hundred feet of 

 excavation through the water to do ; the big ship had two thousand feet of 

 excavation, and the lineal dimensions of the one were to the lineal dimen- 

 sions of the other as 1 to 2'1. The excavation to be done by the big ship 

 in relation to that to be done by the small ship was as two thousand to five 

 hundred feet, or four to one ; but the carrying power was as twenty-five 

 thousand to twenty-five hundred. To propel the big ship they had a nomi- 

 nal horse power of twenty-five hundred, while to propel the smaller vessel 

 there was a nominal horse power of five hundred ; so that the big ship would 

 be worked quite as economically as the small one. Referring again to the 

 wave line, he would suppose that it was given as a problem to any one to 

 design a ship on the wave principle. The first thing to be done was to settle 

 the speed at which the ship was intended to go. If the speed were fixed at 

 ten miles an hour, a reference to the table of the wave principle would show 

 that, in order to effect that object, the length of the ship's bows ought to be 

 about sixty feet, and of her stern about forty. If a larger vessel were re- 

 quired, say a ship of one hundred and thirty feet long, there would by noth- 

 ing more to do than to put a middle body, of thirty feet in length, between 



