12 BULLETIN 835, U. S. DEPARTMENT OF AGRICULTURE. 



within the tank and a few inches within the flume proper. The eil 

 is made of galvanized iron and has a cross-sectional area of 100 

 square inches. The bottom end of the ell is closed with a piece of 

 very fine meshed brass-wire gauze soldered to the ell. The angle of 

 the ell is made sufficient to change the direction of the soil column 

 from the vertical upward to any specified angle. The angles used 

 varied from 45° up to 45° down. 



THE FLUME. 



The flume proper is that part of the equipment designed to hold 

 that part of the soil column extending beyond the outer end of the 

 ell. The bottom and one side of each flume are made of 2-inch red- 

 wood plank lined with galvanized iron. The second side of the 

 Hume is of plate glass, while the top of the flume is open or covered 

 with maltoid roofing. The flumes are 10 by 10 inches in area 

 and of various lengths. The galvanized lining of the flume at in- 

 tervals of 1 foot is ridged or corrugated with 1-inch channels extend- 

 ing up and into the flume. The metal lining on the bottom of the 

 flume is bent down and over the edge of the plank bottom and then 

 bent out and up on the glass side, forming a channel to receive the 

 ed.ge of the glass side. This channel is one-half inch wide and three- 

 quarters inch deep. 



THE GLASS SIDE. 



One side of the flume is of stock plate glass cut 11 inches wide 

 and 30 inches long. The glass is held in place at the bottom by the 

 channel made by extending the lining of the bottom as described 

 above. The ends of the glass are -held in place by double channels 

 made from galvanized iron. These channels are one-half inch in 

 width, three-quarters inch deep, and 10| inches long. The channels 

 are fastened to the bottom of the flumes by means of screws and are 

 held at the top by strap-iron cross-braces fastened to the wooden side. 

 Melted paraffin is run into the channels at the bottom and end of the 

 glass and a tight joint secured. The end of the flume is closed with 

 a metal gate fastened to the wood of the flume. 



SOIL BOXES. 



The all-metal boxes as first used were replaced with wooden boxes 

 having a metal lining. The sizes of the boxes were not altered. 

 They are made of 2-inch redwood plank and lined with galvanized 

 iron. The lining extends out and over on the open side of the box. 

 A strip of plate glass held in place by wooden strips is placed on the 

 open side of the box when ready to set in place after packing. The 

 wooden strips are fastened to the box proper by means of eyebolts 



