42 VARIATION OF FRICTIONAL RESISTANCE OF SHIPS, ETC. 



ships is extremely interesting. From the tests made as reported in the present paper it 

 appears that the average increase on the plates is about four times that reported in Glasgow 

 harbor; in other words, it is about 2 per cent per day. As stated in remarks in the paper, 

 the extension of these results to full-sized ships would require an allowance to be made for 

 the change in coefficient and exponent due to length, and this is a matter which it is hoped 

 may be determined in future investigations. The statement with regard to there being no 

 apparent reason for the increase in fouling, in that the surface of the vessel seems exceed- 

 ingly smooth and even slippery, is also confirmed by the experiments made at the Experi- 

 mental Model Basin, in which it is shown that surfaces which have been oiled or coated 

 with soap have more resistance than the plain, hard-varnished surface. It must be confessed 

 that this result is contrary to that which might naturally be expected from a priori reason- 

 ing. If arrangements could be made to run a trial trip of a vessel at equal intervals, say 

 of two months, over a period of a year, it might be possible to get further light on this 

 interesting and important subject. 



The President : — We will now take up Paper No. 2, entitled "Recent Progress with 

 the Active Type of Gyro-Stabilizer for Ships," by Mr. Elmer A. Sperry, Member. 



Mr. Sperry presented the paper. 



