1 62 TRANSPIRATION AND ASCENT OF SAP ch. 



their naked ends are exposed on opposite sides of a flat 

 vertical support. To effect this they were passed 

 several times through a piece of thin cardboard in 

 such a manner that when the card was bent and folded 

 across the support the stitches made of the two wires lay 

 on opposite sides. 



Fig. 27 shows the arrangement. T is an H -shaped piece 

 of tinned iron about 5 5 cm. long. The cross-piece of 



the H is represented by 

 a broad band about 3 cm. 

 wide. It is covered by 

 a thin piece of cardboard 

 C about 1*2 cm. by 5 cm. 

 This card carries three 

 stitches of the ends of 

 the leads on each side 

 of its middle line. The 

 ends of the card are 

 folded round the cross- 

 piece of the H, and the 

 iron is folded in the 

 middle along the dotted 

 line (Fig. 27A), so that 

 the ends of the card are 

 nipped within the fold. 

 Then the four ends of 

 the H are bent out at 

 right-angles to the folded middle-piece, so as to form a 

 stand to support this in a vertical position (Fig. 27B). 

 To prevent the ends of the leads making contact with the 

 iron, two plates of mica (M, Fig. 27B) are slipped between 

 the leads and the iron one on each side of the vertical 

 portion. The mica plates are held in position by the 

 cardboard. 



Connection between the ends of the leads exposed on 

 this support and those coming from the galvanometer 



,M 



