GREENHOUSE CONSTRUCTION AND HEATING 33 



most popular size. Glass of this size is generally laid 

 with the sash bars 16 inches apart, although a small per- 

 centage of vegetable growers lay the glass with the sash 

 bars 24 inches apart. Except in full iron construction, it 

 is doubtful whether the roof-bars should be so far apart, 

 because of the increased breakage by the weight of snow, 

 and the difficulty of making and maintaining tight joints 

 at the laps. There is probably no objection to the bars 

 being 20 inches apart ; this distance makes it possible to 

 use 20 x 24-inch glass, which costs only a trifle more than 

 16 x 24-inch glass. 



Fig. 20. A corridor leading to the packing room in a large range. 



The greenhouse grower has been quite successful in 

 guarding against losses caused by snow, hard winds and 

 very cold weather, but his houses are at the mercy of 

 destructive hailstorms. To protect him against this loss, 

 hail insurance companies have been organized. One of 

 the leading companies charges 8 cents a 100 square feet of 

 single-strength glass and 6 cents for double-strength. It 

 is just as important for the grower to protect his property 

 from losses by hail as from those by fire. 



