LAUNCHING DATA FOR A BATTLESHIP. 



101 



DISCUSSION. 



After reading the paper, Mr. Taw- 

 resey said : — 



"Since writing the paper I have 

 learned that the photographic method 

 was used in determining the launching 

 velocity for the battleship Delaware built 

 by the Newport News Shipbuilding Com- 

 pany ; also that Naval Constructor Eggert 

 used the method devised by him in con- 

 nection with the launching of the Wash- 

 ington, which was somewhat earlier than 

 the earliest date mentioned in the paper. 

 I think Mr. Eggert's work deserves recog- 

 nition, as he is the first, so far as I am 

 aware, to introduce the photographic 

 method of observation. He did not have 

 a moving-picture apparatus at hand, but 

 had to devise modifications of the ordi- 

 nary hand camera, and to adapt it to the 

 purpose. 



I have here a diagram which is not 

 included on Plate 38 of my paper, and 

 which will illustrate the method used to 

 determine the exact point of pivoting. 

 The paper states that the ship commenced 

 to pivot after a travel of 569 feet. That 

 was the point adopted by an examination 

 of the moving-picture film, examined 

 from picture to picture, and confirmed by 

 the same method used here, except that on 

 finally plotting the curve numerical errors 

 were discovered in estimating two points 

 here (indicating on the diagram on black- 

 board). This is a corrected curve which "^ 

 gives the point at which the ship com- 

 menced to pivot, as being after the ship 

 traveled 560 feet. These (indicating) are 

 the tangents of angles, values of .01 to 

 .06. The slope of the ways was 11/16 

 of an inch to the foot, which corresponds 

 to an angle having a tangent of .057. 

 This (indicating) represents the tangent 

 of the slope of the ways. The position 

 of the ship was examined from the pho- 

 tograph and the angle of trim for differ- 

 ent pictures determined. 



31U3S i.N39Ntfl 



