1914] 



OTIS— TRANSPIRATION OF WATER PLANTS 



463 



terminated 



This collar was 



provided with a socket into which was slipped a solid brass rod, or 

 point, pointed at its upper end. The points were first turned up 

 in a lathe, after which they were placed in a form and ground on an 



microsc 



same angle and of a uniform 



The angle of the 



experimentally 



the best results. 



of 120 with each other were three iron radius rods terminating in 



Screwed into the sides of the collar at angles 



Fig. 2 



the heavy iron band at the rim. The outer extremity of the rods was 

 threaded for a considerable distance, so that by means of lock-nuts 

 and rubber gaskets on either side of the heavy band the point 

 could be centered with ease and accuracy. It was essential that 



tank 



»— ^ 



made 



from 



The points in all the tanks were 



set at a distance of 4.5 cm. below the level of the rim. 



hich 



gh hemlock lumber 



grade 



boxes 



