^•'' 



IIOR 



ground is slippery and much up hill ; 

 and a turn-up in front is also useful 

 in rocky places. There is a shoe 

 called the bar shoe, which is of an 

 oval figure, the iron being complete 

 around the heel, curved and thick- 

 ened to suit it ; but it is seldom used : 

 it answers well to protect a tender 

 frog. In putting on the shoe, all the 

 crust trimmed should be taken quite 

 level, and the shoe never put on hot 

 to make it fit better ; it may be gauged 

 while hot for a minute to enable the 

 smith to cut the crust true, but not 

 clmchcd while hot. Racing shoes 

 are very hght, and of the figure 

 above. 



HORSE-CHESTNUT. Msculus 

 hippocasta7iuvi. This tree is remark- 

 able chiefly for the beauty of its fig- 

 ure, flowers, and early foliage. The 

 wood is soft and of httle value. The 

 nuts contain much nutritious matter, 

 which is combined with a disagreea- 

 ble bitter ; but it is said that pigs eat 

 them when pounded into meal. A 

 writer in the American Farmer says 

 that they are very saponaceous, and 

 will take spots out of linen. The 

 Buckeyes are of this genus, or, at 

 least, of the sub-genus Pavia. 



HORSE DUNG. See Farm-yard 

 Manure. 



HORSE-FLY. Hippobosca, which 



S66. 



HORSE-HOE. See Cultivator. 



HORSE POWER. In physics, 

 the effect produced by the strength 

 of a horse. James Watt allowed in 



HOR 



his engine an effect equal to 32,000 

 pounds lifted one foot in a minute ; 

 but from experiments with horses, 

 D'Aubuisson found it was only equal 

 to 10,440 pounds raised one foot in a 

 minute. 



In agricultural machines, a horse 

 power is a contrivance or gearing to 

 make the labour of horses available in 

 turning thrashing and other machines, 

 where great swiftness is wanted. 



The simplest horse power (,Fig. 1) 



6 feBs::.^^ Fig- 1- 



is a triangular wooden frame bearing 

 a wheel, the upper axis of which is 

 inserted into the lever, a ; the horse 

 is hitched at b, and, as he walks in a 

 circle, turns the wheel, d, which 

 plays into an endless screw, the 

 end or rod of which, c, is made to 

 revolve rapidly, and may be put in 

 communication with a machine by 

 the hook or by a small roller. The 

 same arrangement, with several ad- 

 ditional wheels to multiply motion, 

 and a crown wheel instead of the 

 endless screw, forms Warren's horse 

 pmcer {Figure 2), as well as other 

 kinds. 



The old power for tlirashing con- 

 sisted of an upright beam, carrying 

 at the top a crown or bevelled wheel 

 of large circumference, and turning a 

 small wheel, which was directly in 

 contact with the thrasher or grinding 

 mill. The horses were attached to 



levers, projecting from the central 

 beam, and below the wheel. This is 

 a simple and very efficient contri- 

 vance. A modification is introduced 

 by Mr. Scripture, who puts no cogs 

 to the wheel, but causes it to turn a 

 roller by friction. 



403 



