1902.] PUBLIC DOCUMENT — No. 33. 83 



to obtain from practical lettuce growers and others who have 

 heated their soil, the cost, including coal, labor, etc., but not 

 the cost of the tile or apparatus used, is as follows : — 



In a house 225 feet long by 20 feet wide, one-third of 

 which was heated at a time by steam passing through 2 inch 

 tile placed 8 inches below the surface and 1 foot apart, and 

 forming a continuous circuit, the cost was at the rate of $16 

 per 1,000 cubic feet, where the pressure of steam used varied 

 from 30 to 80 pounds. This house had been previously steril- 

 ized by the same method, excepting that the tiles were placed 

 18 inches apart, instead of 1 foot, with less favorable results. 

 The heating was continued da}^ and night, as this could be 

 easily done, on account of a night foreman being employed. 

 The estimated cost of removing' the soil from a house to the 

 depth of 1 foot, which was actually done in a similar house 

 a few years ago, and placing in new soil without carting the 

 same, was at the rate of $37.50 per 1,000 cubic feet. 



Another house, 40 feet wide by 300 feet long, was treated 

 by a lettuce grower with an average pressure of 30 pounds 

 of steam passed through 1 inch iron pipes, furnished with a 

 series of perforations 6 inches apart and %g inches in diam- 

 eter. These pipes were made up into a frame, 7 inches dis- 

 tant from one another. The estimated cost of sterilizing 

 1,000 cubic feet of soil, based upon the treatment of the 

 whole house, was $8.33. 



A lettuce grower who has a range of houses each about 

 300 feet long by 36 feet wide has recently treated them all 

 by steam. A boiler house, situated at the most convenient 

 place on the establishment, was constructed, and a new forty 

 horse-power boiler was placed in it, to be used exclusively 

 for the purpose of sterilization. The sterilizing apparatus 

 consisted of a series of 3 inch T's, furnished with 2 inch 

 nipples, which was placed in the centre of the apparatus, 

 thus forming a header. From these nipples there extended 

 in each direction a series of perforated 2 inch iron pipes 

 which were 10 feet in length (see Fig. 2). This made the 

 apparatus when complete about 20 feet long and 8 feel wide. 

 The apparatus was placed on the surface of the soil, the ends 

 of the pipe stopped 14) with wooden plugs, and the earth 



