10 



T. Lyttleton Lyon and James A. Bizzell 



cone. Between this cone and the sand in the tank, gravel is placed 

 to support the sand and facilitate drainage. The cap, the rod, and the 

 cone may all be removed if the outlet becomes clogged, but it has never 



been necessary to do this. From the lower side of 

 the drainage tube a smaller tube projects, and over 

 this is drawn a rubber tube to conduct the water to 

 the receptacles in the tunnel. 



The drainage, water is caught in galvanized iron 

 cylinders, of which there are two for each tank. One 

 cylinder has a side tube near the top which fits into 

 a hole in the one next it, so that when the first 

 cylinder becomes full the water may flow into the 

 other. The cylinders are of such a diameter that 

 each centimeter in depth represents 800 cubic centi- 

 meters of volume, and each cylinder holds about 

 60 liters. The drainage is measured by running a 

 meter stick into the cylinder and measuring the 

 height of the water. The volume is then easily 

 computed by multiplying the number of centimeters 

 of depth by 800, to get the number of cubic centi- 

 meters. An aliquot sample is then removed and 

 the remainder of the water is allowed to run off thru 

 a faucet in the bottom of the cylinder. The waste 

 water is conducted by gutters in the tunnel to drains 

 which carry it away. The samples for analysis are 

 placed in milk cans lined with paraffin. An anti- 

 septic is always kept in these sample cans. 



The soil used 



Fig. 3. vertical sec- 

 tion OF drainpipe 



Tanks 1 to 12, which were the ones used in this 

 experiment, were filled during the summer of 1909 

 with soil from Caldwell Field on the university farm, 

 the soil being excavated to a depth of 4 feet in layers of 1 foot. 

 These layers were placed in the tanks in the order in which they were 

 present in the field, the funnel-shaped bottom having previously been 

 filled with sand. In each tank 3| tons of soil was placed, being tamped 



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