COLLINS AND KEMPTON I A FIELD AUXANOMETER 



205 



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field conditions and sufficiently simple and inexpensive to permit 

 the use of a number of instruments at one time. The following 

 description is published in the belief that the instrument may- 

 be found useful in other fields. 



The instrument is illustrated diagrammatically in figure 1. It con- 

 sists of a light wooden box, a, 4 inches square and 12 inches in height 

 constructed of \ inch material. Passing en- 

 tirely through the box is a glass rod or tube, 



b, about f-inch in diameter and about 20 *>- 

 inches long. The lower end of this rod is 

 attached to the growing plant by means of a 

 copper wire and a light clip or wire hook. 

 The rod is supported b}' a cord attached to 

 a close fitting cork, e, through which the 

 rod is passed. The cord leads over a pulley, 



c, to a counterpoise, d. The recording pen, 

 /, is made of thin sheet copper bent into a e _ 

 shallow trough and attached to a light 

 wooden arm supported on the cork. The 

 driving mechanism consists of an ordinan r 

 alarm clock, g, placed face down. The 

 milled head used in setting the hands is 

 removed and replaced by a f-inch brass 

 rod, 7 inches long, drilled and slotted at the 

 lower end in the same manner* as the dis- 

 carded milled head. A shallow groove also 

 is cut in the upper end of the rod. The 

 drum, h, for carrying the record paper is 

 made of a section of a pasteboard mailing 

 tube filled at either end with a perforated 

 cork, through which the brass rod passes. 

 A pin passed through the cork at the upper 

 end rests in the shallow groove in the top 

 of the brass rod. The counterpoise string 

 for lifting the glass rod is attached near the 

 edge of the cork, e, and the pressure of the pen on the drum 

 regulated by a slight turning of this cork. 



A convenient method of supporting the machine is to drive a round 

 wooden stake by the side of the plant to be measured, on which a 



Fig. 1. Field auxanometer. 



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