103 JSrEfHAINlCS. 



of the force exerted. To prevent tlie pencil from con- 

 stantly marking on the same line, the paper is made to 

 move slowly in a side direction, so that all the vibrations 

 are shown, as represented in fig. Ill, and they may be ac- 

 curately examined and read off at leism-e, a and h repre- 

 senting the forces of two different plows, drawn through 

 a single furrow across the field. The motion of the paper 

 is effected by being placed on two rollers, one of which 

 unwinds it from the other. This roller is made to turn by 

 Fig. 112. means of a wheel running on 



the ground, which gives mo- 

 tion to the roller through an 

 endless chain, working a cog- 

 wheel by means of an endless 

 screw. The cylindrical dyn- 



Sdf-Ttcording Dynamometer. amomctcr, showU in fig. 112, 



is used for this purpose, lengthwise upon which the two 

 rollers are placed for holding the paper. With this in- 

 strument a permanent register might be made of the 

 force required for different plows, with an accuracy not 

 liable to dispute. 



WATEKMAX'S DYJ^^AMOMia'EE. 



All difficulties have been completely overcome by the 

 recent invention of II. Waterman, of Hudson, N. Y. His 

 dynamometer was used with entire success at the Auburn 

 reaper trial in 18GG, and at the trial of plows at Utica, in 

 18G7, under the Committee of the N. Y. State Agricul- 

 tural Society. A full description of all the parts would 

 require too much space for the character of this work; the 

 following is a brief explanation of the mode of its opera- 

 tion : 



This dynamometer is furnished with a spiral spring, 

 like those we have already described, working a piston in 

 a cylinder of water. To this, two dial plates are added 



