Supplementary Plow Trials. 



265 



fifth experiments was 136 pounds, which was caused by the 

 seventy-fifth being turned up hill, and also to the roots of the 

 hardback, which varied from one-eighth to three-eighths of an inch 

 in diameter. The soil was very moist from recent copious rains. 



Governor F. Holbrook was kind enough to procure for us the 

 various plows, with the necessary adjustments required for the 

 trial; and also, at our request, negotiated for the use of the land 

 and for the the teams and assistants. 



We obtained the assistance of Mr. Henry Brooks, of Concord, 

 well known as a very skillful plowman, and his services as such 

 were perfectly satisfactory. 



Governor Holbrook, of Vermont; Governor Brown, of Massa- 

 chusetts, and Mr. Joel Nourse, of Boston, the inventor of the 

 well known Eagle plow, were present with us at all the trials, 

 and their advice and assistance were of great value. Mr. G. 

 Tucker, of the Country Gentleman, was also with us during the 

 whole time. 



We began our experiments with two horses, but finding it 

 difficult to preserve a perfectly uniform breadth of furrow, owing 

 to the irregularity of their walking, we used four horses, walking 

 in pairs, so that the irregular walk of one team compensated for 

 the irregularity of the other. Finding that four horses made the 

 experiments so much more satisfactory, we continued the use of 

 them throughout. 



I. Experiments to determine the increase of power required 

 for each successive inch of depth in plowing with 



Holbrook'' s Swivel Plow, JSTo. 4: 



