Methods of Treating Sick Soils 55 



steam operates. When one pan is used, a traction 

 engine or a portable boiler of ten to twelve H. P. 

 will suffice. While the standard size of the pan is 

 six by eight feet, the dimensions may be modified 

 to suit the size of the seed beds. 



Selby and Humbert 1 describe the method of con- 

 structing an inverted (fig. 9) 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 varying from two to three feet in width by eight 

 to ten feet in length. Figure 9 shows a pan 6 x 10 

 feet in size, 6 inches deep, constructed from five such 

 strips 2}^x8 feet in size. These sheets are joined by 

 double-fold seam and riveted at intervals 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 i}i i ncn angle iron across the top and extending 

 down the sides. This is bolted at the sides to the 

 supporting strap iron stiflener. The corner illustra- 

 tions show at 'A' the joint used for the galvanized 

 iron sheets, and ' B ' a section of the angle iron sup- 

 porting the top. 



"The entrance pipe for the steam may be placed 

 at the side or end of the pan (see dotted construction 

 lines of fig. q) or may enter from the top as per illus- 



1 Selby, A. D., and Humbert, J. G., Ohio Agr. Expt. Sta. Circ. 151 : 

 65-74. I9I5. 



