VOL. XIV.] PHILOSOPHICAL TRANSACTIONS. 63 



2, 3, 4, 5, &c. hours. — 3. The difference of speed that a man can make under 

 several burthens within the same time. — 4. Let the difference between the 

 weight of a common Irish car and the burthen which a horse can draw upon it 

 be examined; as also the like difference between a cart for 5 horses and its bur- 

 then, and between a coach with a coachman with its burthen, and between the 

 pack-saddle and of a pack-horse with its burthen. — 5. Let the difference between 

 a horse's draught on a small car, and a 5 horse's draught on a great cart and 4 

 wheeled waggon, be examined. — 6. Let the same differences of horses draught 

 at several distances from the carriage, and upon wheels of several heights, be 

 examined. — 7. Let the just weight of wheels be determined, to make them of 

 the same strength, though of different diameters, and at what distance wheels 

 of several heights should stand from each other. — 8. What the difference is 

 between iron and wooden axles, and of the friction made by them, within the 

 boxes of their naves. — g. What is the true reason of the dishing out of wheels. 

 — 10. What is the true proportion of timber which ought to be in the nave, 

 spokes, or rim of any wheel, in order to lightness, strength, and uprightness. 

 — 1 1 , What is the difference between the high and low hanging of coaches, 

 the distance of the standards, and of the difference between the hind and the 

 fore wheels. 



Other experiments. — Take a parallelopipedon of wood, suppose 4 inches 

 square at the ends, and 8 inches long, with the weight thereof, and try as 

 follows, viz. 



1. How much weight less than that of itself, applied to convenient pulleys, 

 will draw the said log over a smooth level table, of an assigned length, in an 

 assigned time, and what weight will draw the same faster or slower, in any as- 

 signed proportion. — 1. What difference there will be in the friction of the whole 

 side of the said log on the plane table, and mounting the same on 2 small keels 

 of i of an inch thick, — 3. What the difference between the last mentioned 

 mounture, and setting the same upon 4 thick segments of circles, so as to 

 touch the table but at 4 points, in imitation of dragging wheels, and whether 

 it be material that the said segments should be of greater or less circles. — 4. 

 What the difference between the said mounture upon 4 such segments, or upon 

 4 vvheels moving distinctly upon their axles, as also between 2 wheels or 1 seg- 

 ment, like a cart, or 1 wheel and 2 segments, like a wheel-barrow. — 5. What 

 the difference in draught will be in the aforementioned draughts, on the various 

 inclinations of the said table, upwards and downwards, or on the said table co- 

 vered with a blanket equally extended, or with a paste of clay of a certain 

 thickness. — 6. What the difference between the tenderest motion upon wheels 

 and the draught through water. 



