Transportation on Water 



357 



FIG. 124. The "Alliance" passing through Gatun Locks, Panama Canal. 

 This was the first ocean steamship to pass through the canal. 



ship is 15. Show graphically the magnitude and direction of the 



resolved forces. Try different lengths of the towline, for example, 



three times the first length, and find the magnitudes of the effective 



and wasted forces. Will the 



effective force be greater or J ^-z.~z^:~~^ - s -,^ 



less with increase in length of ^ _ J-b TRACTOR ^ 



the towline? How does the 



effective force depend upon the 



angle made by the towline 



with the direction of the ship ? FIG. 125. Towing a ship through a canal. 



Application to sailing. To return to the sailing boat and 

 the problem of its making headway when the direction of the 

 wind forms an angle of 45 with the direction of the boat, we 



