134 REPORT—1868., 
7. 2, mean of squares, and f*, mean of fourth powers, of sines of angles 
of obliquity of streamlines of forebody at their points of inflexion. 
Calculated thus :— +d 
Sines of Squares of 4th power 
Water-lines, obliquity. sines. , of sines. 
1 ‘0871 KIC ‘0075 on Ha *000057 
2 1391 Sacheckd 0193 is 000374 
3 1736 GT "0301 bean -000908 
4 2079 ee 0432 S580 “001868 
5 *2419 aes 0585 HK 35 003424 
6 ova 2588 ewe “0669 fee "004486 . 
GW siss "2923 tus 0854 wheat 007299 
Sums +3109 Wee °018416 
Means :0444=,?.... 002631 =/3* 
6 and 7 should be measured upon normal lines if possible. In the present 
case the angles have been measured upon water-lines, as shown in the half- 
breadth plan. 
8, A, augmented surface in square feet-=LG (1+46°+ f°), 
or Log L = 2-5269851 
Log G = 17160033 
Log 1+43°+3* = 0:0719556 
43149440 
Nat! n® 
20651-=augmented surface. 
The factor 144 3°+ /3* is called the “ coefficient of augmentation.” 
9. A’, correction of augmented surface, in square feet, or 5607 QV 1—m?. 
This quantity disappears in the present case; because m > 1; and it has 
to be calculated for those vessels only in which the afterbody is too short 
for the speed. 
(A+A)x V" 3307). 
ee ee 
10. Coefficient of propulsion 
The meaning of the term “ Augmented Surface ” is explained by the fol- 
lowing extract from the ‘ Transactions of the Institution of Naval Archi- 
tects,’ vol. vy. 1864:—‘ The resistance to the motion of the ship, due to the 
production of frictional eddies, by a given portion of her skin, is the product 
of the following factors :— 
«JT, The area of the portion of the skin in question. 
“TJ, The cuhe of the ratio which the velocity of gliding of the particles of 
water over that area bears to the speed of the ship, being a quantity depend- 
ing on the figure of the ship and the position of the part of her skin under 
consideration. 
“TIT. The height due to the ship’s speed, that is (in feet), 
2 
(speed in feet per second)? os (speed in knots)? 
64-4 ; 22:6 ‘ 
