Treatment of Sick Soils 35 



Selby and Humbert* describe the method of con- 

 structing an inverted pan as follows : 



"Material used for construction of a pan is gal- 

 vanized sheet iron ; the most useful weight is No. 20 

 gauge, which weighs 26.5 ounces per square foot. 

 The heavier material requires little in the way of 

 frame supports. The galvanized iron sheets come 

 in sizes vary^ing from two to three feet in width by 

 eight to ten feet in length. The standard is a pan 

 6x10 feet in area, six inches deep, constructed from 

 5 such strips x 8 feet in size. These sheets arc 

 joined by double fold seam and riveted at inter- 

 vals of 6 to 10 inches to make the pan steam tight. 

 This pan is further strengthened by a band of strap 

 iron 2x1 inch riveted to the bottom edge, and 

 stiffened by a brace of ij^'ii^ch angle iron across 

 the top and extending down the sides. This is 

 bolted at the sides to the supporting strap iron 

 stiffener. 



''The entrance pipe for the steam may be placed 

 at the side or end of the pan or may enter from the 

 top. The latter form has the advantage in that it 

 will not interfere with the box boards when used 

 on frames. The pipe, after entrance, should be a 

 T form, so that steam in being forced into the pan 

 when in place does not blow holes in the soil." 



The pans, together with the sand bags used for 

 weight, are mounted on a frame which rests upon 

 wheels. The wheels run on the edges of the con- 



♦Selby, A. D., and Humbert, J. G., Ohio Agr. Expt. Sta. Circ. 

 151: 65-74, 1915. 



