104 

 The setscrew, s.b., placed on the wire above the lov;ei' (^xiicie 



prevents any further di'op. V.Qien the steel v/ire holda the door 



the dirk is 2nM. below the naj-^net; when tiie disk is drnv/n up 



to the matinet, l/2inn. clearnnce is allowed for the door. Pack 



of the feeding box A, is placea the inclined plane, J. .P. 



The inclined plane has a hard rubber base ?^/B inch 

 thick, 6 incites long and 2 3/6 inches wide. Upon standards 

 at the middle of the base I'ests the plane itself. The plane 

 is of wood fibre and of the seixne dimensions as the ba.se. The 

 plane is weighted at the end nearest the box in order to in- 

 sure its return to position iifter use. At the end opposite 

 the weight, platinum electrical contacts, e.c, are placed 

 in both base and plane. The power is provided through wires 

 connecting with the regular electric lighting system, direct 

 current, 115 volts. A 32 c.p. laiJip is placed in the series 

 in order to avoid any danger of short-circuiting. In order 

 to make the contact and allow the current to pass through the 

 magnet, thus raising the steel wire and releasing the door, 

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

 0, which lies well out toward the end of the plane. Cn 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 furtlier action, remctining on point o until the click 

 of the disk meeting the magnet is heard. Over the food box 

 and plane is placed a cage constructed of 1/2 inch heavy wire 

 nesh, the base measurements of which are 24 x 24 inches and 

 the height 14 inches. This allows the rat ample room to explore 

 on all sides and above the food box. V.'hen the rat is within 

 the entrance, e, to the cafc,e is closed. 



The preliminary inclined plane experiment was not 

 intended so much as a decisive experiment as tio test the ef- 



