CONTENTS. 



Page 



ON DRAUGHT . . 403 



The power of the horse, how calculated: difference of opinion as to wheels: 

 draught regarded as to the act of drawing, and the resistance to the power employed : 

 the moving power. Animal power is the application of the strength of an animal • 

 and mechanical power is power employed through the intervention of machinery : 

 horse power and that of the steam-engine compared, as to interest of first cost 

 decrease of value, hazard of loss or accidents, value of food, or coals and water 

 renewals and repairs, harness, shoeing, farriery, stabling, and expense of attendance : 

 the power of draught, or effect produced by each : the obstacles to be overcome in 

 the use of machinery. The manner in which the animal adapts himself to his load : 

 errors with regard to this in some ancient sculptures : real action of the horse in 

 walking, trotting, and galloping. The resistance to draught should be rigid, and void 

 of elasticity, but should not be constant and unremitting : a horse pulls better when 

 close to his work : the disadvantage of long teams. The effect of draught depends on 

 the speed, the power of the animal, and the time employed: calculation and com- 

 parison of these : the hours of labour should not exceed six hours : the rapid reduc- 

 tion of the power of the horse when his speed is increased. A flat piece of road more 

 destructive to the horse, than one with alternate rises and falls. Best direction of 

 the traces : should be nearly horizontal, but varying with the kind of horse, and na- 

 ture of the work and road: inclining the traces downward, the same as throwing 

 a part of the load on the shafts. Ancient mode of harnessing : the collar in the time 

 of Homer : explanation of the power of the South American lasso. The advantage 

 of transporting goods by water, consists in the smallness of power required; this 

 rapidly increasing with the speed : calculation of the draught of a canal boat. The 

 advantages and disadvantages of sledges and rollers : manner in which the rock 

 forming the pedestal of the statue of Peter the Great was moved on rollers : the best 

 construction of the roller. Description of the ancient war chariots : the mechanical 

 advantage of the wheel increased in proportion to its height: the resistance depends 

 on the friction at the axle : comparative advantages of different materials as used for 

 axles : axles working in iron boxes : calculation of the force of draught required for 

 a four-wheeled cart on different roads : comparison between narrow and broad 

 wheels : description of dishing the wheels, and advantage of : comparison between 

 conical and cylindrical wheels : injury received by the roads by different wheels : the 

 cylindrical wheel a little dished, and the edges rounded off, is the best : ruts form a 

 great resistance to draught : the hind wheels should exactly follow the track of the 

 fore ones : description of Jones's patent wheels : the expense and weight must limit 

 the height of the wheels : the fore-wheels usually too small : the comparative ad- 

 vantages of two and four-wheeled carriages : two wheeled carts with two horses, 

 disadvantageous. Springs should never be applied to give any longitudinal elas- 

 ticity to the carriage : disadvantage of C springs on this account : advantage of 

 springs : Mr. D. Giddy's theory of wheels and springs : springs particularly advanta- 

 geous when much velocity is required : loading high, although dangerous, makes the 

 carriage run light : the safety coaches, by having the load low, very disadvantageous. 

 Hardness, the great desideratum in roads : great rounding of the road useless, and 

 injurious : a rise of six or eight inches in a road twenty feet wide, quite sufficient : 

 hardness of surface, how best secured : constant repairs and attention, on the whole, 

 most economical. Great advantage of railways : the power of the horse increased 

 tenfold on a railway. 



