TIME AND TRAVERSE TABLE. 



79 



It therefore becomes a consideration, when reduced to low rates under steam alone, by the 

 resistance of wind and sea, if by the assistance of sail and consequent increase of speed a 

 given point to windward cannot be made in equal or less time. For example, if the speed 

 from the above causes, in a direct distance of 2300 miles, be reduced to 3 knots per hour, 

 767 hours will be occupied in the performance ; but by making sail and a 4 point course, 

 (thus increasing the speed to 4| knots,) the same position will be gained in 723 hours, running 

 over a traverse distance of 3253 miles. 



Again, should the wind enable the vessel to lay up 2 points from the direct course, at the 

 same increase of speed, it will be accomplished in 668 hours, running over a traverse distance 

 of 3005 miles. 



Other speeds also afford relative advantages in the same manner ; and with the use of the 

 following table, they may be roughly estimated by inspection. 



It being decidedly ascertained that H. M. steam-vessels of war, with wheels disconnected, 

 can work within 1 1 points of the wind, making 8 knots, consequently a 6 point course becomes 

 a free wind. When at and beyond that, the sails will frequently impel the vessel beyond her 

 maximum engine speed, whereby the whole expenditure of fuel, wear and tear, can be 

 saved. 



These advantages are more applicable to long runs, where the wind is rarely right 

 ahead for any considerable distance, but veers so as to enable a long line to be made on one 

 tack or the other. For illustrations, see Plates XXVII. and XXVIII. 



TRAVERSE TIME TABLE, for the purpose of showing the comparative advantage 

 obtained with a steam-vessel when upon an oblique course and assisted with 

 canvas, over the same vessel upon a direct course, without canvas, and with a 

 diminished velocity. 



