TABLE FOR ATMOMETERS 159 



oration are requisite, an electric fan may furnish a stream of air 

 crossing the table in any direction. The apparatus is so satis- 

 factory for standardizing cups to standard cups, and so simple in 

 construction, that it seems to warrant brief description. 



The table is 8 feet in diameter, turned about once per minute 

 by means of a small motor belted to a reducing gear. 2 The bear- 

 ings are practically without friction, being formed from two 

 ordinary rear bicycle hubs, usually cheaply and easily procured. 

 Riveted through some of the spoke holes, to the lower flange of 

 the lower hub (fig. 1, A) is a |-inch grooved pulley, 4 inches in 

 diameter, this taking the place of the discarded sprocket wheel. 

 This pulley is reached by a leather belt from the reducing gear, 

 running beneath the table. 



To the upper flange of the lower hub (fig. 1, B) is similarly riv- 

 eted a rg-inch steel plate, 6 inches in diameter, perforated near its 

 margin for four stove bolts (fig. 1, E), equally spaced. Suspended 

 below this plate is a second and larger one (12 inches in diameter, 

 fig. 1, C), unattached save by means of the four bolts just men- 

 tioned, which screwinto properly tapped holes. The larger plate has 

 at its center a circular opening large enough to allow of its being 

 slipped into place over the upper flange, before the first plate is 

 attached. It bears near its margin twelve equally spaced per- 

 forations, tapped to take stove bolts (fig. 1, e). 



The radial arms of the table (fig. 1, D) arranged like the spokes 

 of a wheel, are of f by 3 inch wood. Their inner ends are laterally 

 chamfered so as to allow them all to fit together about the lower 

 hub. They are thrust horizontally into the space between the 

 two plates above described, some being cut a little to allow for 

 the four suspending bolts, these bolts are then tightened with a 

 screw driver, and the lower plate thus raised clamps their inner 

 ends into space. After proper adjustment of the arms, a bolt 

 with a washer (fig. 1, e) is passed through a suitable hole in each 

 wooden arm, a short distance beyond the margin of the upper 

 plate, and is screwed tightly into the corresponding tapped hole 



* 2 By far the best gear that I have found on the market — suitable for any physio- 

 logical purpose for which such device is requisite — is furnished by the Eberbach 

 and Son Company, Ann Arbor, Mich. 



