198 



APPENDIX. 



The result of Mr. Mornay's calculation is 151-69 horse power. 



For the calculation of the EFFECTIVE POWER we have a = 5, k = 9-355, n = 15, speed of 

 the vessel = 8-15 miles per hour, and S = 350, with which we proceed as follows : 



log. S 2-54407 

 v 1-07749 



Sv 

 1000 



0-62156 



log. V 2 2-33432 

 B 9.98874 

 0-62156 0-62156 



2-94462 



880-28 

 443-79 



1324-07 

 1235-74 



Effective horse power 88'33 



Mr. Mornay makes it 88-275 horse power. 



For the EFFECTIVE SURFACE OF RESISTANCE, we have, according to equation (p), 



log. 88-33 1-94611 

 v 3 3-23247 



const. 



[_ S' = 28-56 square feet of resisting surface, which is 

 about -rhrths of the immersed sectional area of the vessel. 



Mr. Barlow, page 76, estimates the resisting surface at -Jyth o f the sectional area. 



The PROPORTION OF THE POWER THAT is EFFECTIVE, when the common wheel is em- 



ploved, is . A. P 3 2B V + B V 2 if x <} eno te JL the ratio of the velocities, we 



V A V 2 2BVw+Br V 



have, 



Proportion of power effective = x 



2B 



P 



A 2Bx + B x 2 



the factor z may be taken out roughly from the following table : 



= xz, where the value of 



