TRENCHING AND SUBSOILING. 65 



asked implement makers to devise a system which would 

 enable them to perform deep cultivation with two to four 

 animals only, during the slack season. Naturally, they were 

 ready to give more time to the operation, this question being 

 only of secondary importance, considering that a permanent 

 improvement of the soil was required, and not a merely annual 

 ploughing. Then in the year 1882 the construction of horse- 

 gins applied to the hauling of ploughs was first attempted ; 

 a few years later these machines were used with success to 

 clear and throw into culture Algerian plains, other colonies 

 following this example. 



To solve the problem, a motor, consisting of a capstan, 

 -was interposed between the plough and the team. 



Any animal furnishes its maximum power when it is re- 

 quired to exert a certain effort F, at a certain rate V. 



To give an example, we quote the following figures 

 resulting from a large number of trials : 



Weight of the Animals. Mean Effort Exerted. Rate per Second. 



Horse. 



660to9901bs. ... 143 to 154 Ibs. ... 27 '5in. to 29 'Sin. 



990 to 1,320 Ibs. ... 198 to 242 Ibs. ... 25 "Sin. to 27 'Sin. 



1,320 to 1,760 Ibs. ... 264 to 330 Ibs. ... 23'6in. to 25 'Sin. 



Bullock. 



550 to 880 Ibs. ... 121 to 154 Ibs. ... 27'oin. to 29'5in. 



880 to 1,1 10 Ibs. ... 198 to 242 Ibs. ... 23'6in. to 25'5in, . 



1,110 to 1,540 Ibs. ... 352 to 440 Ibs. ... 19'6in. to 21'5in. 



These figures correspond to a period of useful work of 45 

 minutes per hour, and an average duration of eight hours' 

 work per day (360 to 400 minutes per day). When several 

 animals are yoked together the mean effort diminishes, for 

 the animals never pull simultaneously. The walking pace 

 we may represent by the following figures, the useful effort 

 furnished by each animal when yoked together with 

 others*: 



* As an example of this in practice, let us assume a horse working alone 

 furnishing a mean effort of 198 Ibs.; the effort of a pair will then be 

 198 X 2 X Q'93 = 368'2 Ibs. The effort of four animals working abreast 

 will be 367-4 Ibs. X 2 X 0'93 = 683-3 Ibs., while if the animals are yoked in 

 tandem we will only have 198 Ibs. X -4 X 0*75 = 594 Ibs. Assuming a 

 bullock exerting a mean effort of 220 Ibs., two bullocks abreast will give 

 220 Ibs. X 2 X 0-93 = 409-2 Ibs. ; two pairs will furnish a mean effort of 

 409"2 Ibs. X 2 X 0-93 = 761 Ibs. 



6279. E 



