26 GARDNER CHENEY BASSET 



twelve inches base, eleven inches in height, and is covered on 

 top and sides with three-eighths inch heavy wire mesh. It is 

 fitted with a hard rubber door, d, three-sixteenths inch thick, 

 five inches high, and four and one-fourth inches wide. To the 

 inner side of the door is fastened a cord which passes over a 

 pulley, p, and is weighted at the other end with a piece of lead, 

 1, of sufficient weight to insure the opening of the door upon 

 releasing the latch. B shows the device for latching and re- 

 leasing the door. A short distance above the door is fastened 

 a three-inch electrical magnet, m; directly below that is a steel 

 wire, S.W., surmounted by a steel disk, s.d., of the same diameter 

 as the core of the magnet. The steel wire holds the door by 

 dropping through holes in two brass plates, g, which serve as 

 guides, to a point, behind another brass plate which is set at 

 the top of and behind the door, one and one-half millimeters 

 below the top. The setscrew, s.s., placed on the steel wire above 

 the lower guide prevents any further drop. When the steel wire 

 holds the door the disk is two mm. below the magnet; when 

 the disk is drawn up to the magnet one-half mm. clearance is 

 allowed for the door to swing back. Back of the feeding box, 

 A, is placed the inclined plane, I. P. 



The inclined plane has a hard rubber base three-eighths inch 

 thick, six inches long, and two and three-eighths inches wide. 

 Upon pivot standards rising from the middle of the base rests 

 the plane itself. The plane is of wood fibre and of the same 

 dimensions as the base. It is weighted at the end nearest the 

 feeding box in order to insure its return to position after use. 

 At the end opposite the weight and farthest from the feeding 

 box, platinum electrical contacts, e.c, are placed in both base 

 and plane. The power is provided through wires connecting 

 the regular electric lighting system, 115 volts, direct current, 

 with the wired apparatus. A 32 candle power lamp is placed 

 in the series in order to avoid any danger of short-circuiting. 

 To make the contact and allow the current to pass through 

 the magnet, thus raising the ste^l wire and releasing the door, 

 it is necessary for the rat to step on the point of operation, o, 

 which lies well out toward the end of the plane. On account 

 of a certain amount of latency in the operation of the magnet, 

 the rat must not only make the contacts touch, but must also 

 inhibit further action, remaining on the point of operation until 



