viJ, CONTENTS. 



Page 

 ON DRAUGHT 403 



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

 dnuighl regaided as to 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: 

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

 ;he 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. Tlie resistance to draught should be rigid, and 

 void of elasticity, but should not be constant and unremitting: ahorse 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 comparison of these: the hours of labour should not exceed six hours: the rapid 

 reduction 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 nature 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: ex])lanation 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 : comj)aralive 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 nar- 

 row and broad wheels: description of dishing the wheels, and advantage of: com- 

 parison 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: descrij)tion of Jones' patent wheels: the expense 

 and weight must limit the height of the wheels : the fore-wheels usually too small : 

 the comparative advantage of two and four-wheeled carriages: two-wheeled carts 

 with two horses disadvantageous. Springs should never be applied to give anj' lon- 

 gitudinal elasticity to the carriage: disadvantage of C springs on this account : advan- 

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

 advantageous when much velocity is required: loading high, although dangerous, 

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

 .•lisadvantageou.'i. 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, 

 i^uite sufficient : hardness of surface, liow best secured: constant repairs and atten- 

 tion, on the whole, most economical. Grea' advantage of railways : the power of the 

 iiorse increased tenfold on a railway 



