[ 22 ] 

 IV. On the Power of Horses. By B. Bevan, Esq. 



To the Editors of the Philosophical Magazine and Annals. 

 Gentlemen, 

 T^O determine the average power of horses under different 

 - kinds of labour, has been a subject deemed worthy of 

 the inquiries of many of the first class of scientific writers. 

 It is one of those points which can be determined only by ex- 

 periment. The power to be maintained depends upon the ve- 

 locity; and various formulae are given by writers on this sub- 

 ject. Thus, Professor Leslie gives (15 — v) 2 = pounds avoir- 

 dupoise for the power of traction of a strong horse, and 

 (12 — vf = pounds traction of the ordinary horse, v == velocity 

 in miles per hour. 



In the period from 1803 to 1809, I had the opportunity of 

 ascertaining correctly the mean force exerted by good horses 

 in drawing the plough ; having had the superintendence of the 

 experiments on that head at the various ploughing matches, 

 both at Woburn and Ashridge, under the patronage of the 

 Duke of Bedford and the Earl of Bridgewater. I find among 

 my memoranda the result of eight ploughing matches, at 

 which there were seldom fewer than seven teams as compe- 

 titors for the various prizes. 



The 1st result is from the mean force of each 

 horse in six teams of two horses, each team upon lbs. 

 light sandy soil = 156 



The 2nd result is from seven teams oT two horses, 

 each team upon loamy ground, near Great Berk- 

 hamstead = 154 



The 3rd result is from six teams of four horses, 

 each team with old Hertfordshire ploughs = 127 



The 4th result is from seven teams of four horses, 

 each team upon strong stony land (improved ploughs) = 167 



The 5th result is from seven teams of four horses, 

 each team upon strong stony land (old Hertfordshire 

 ploughs) = 193 



The 6th result is from seven teams of two horses, 

 each team upon light loam = 177 



The 7th result is from five teams of two horses, 

 each upon light sandy land = 170 



The 8th result is from seven teams of two horses, 

 each team upon sandy land = 160 



The mean force exerted by each horse from fifty-two teams, 

 or 144 horses, = 163 pounds each horse; and although the 



speed 



