GREENHOUSES 8/ 



point in the horizon. The best results will be se- 

 cured with the angle of the roof at such a position 

 that the sun's rays will strike as nearly as possible 

 at right angles. More light and heat pass through 

 the glass and the maximum results are secured. In 

 the vicinity of Columbus an angle of from 34° to 

 36° in roofs facing the south will be found to give 

 the best results. The amount of slope is also modi- 

 fied by the probable snowfall during the winter 

 months. In those regions where the snowfall is 

 generally heavy, steeper roofs must be constructed 

 in order to avoid breaking glass. The direc- 

 tion of the slope is also a question of great 



ABOVE SURFACE HOTBED 



importance, yet one upon which it is impossible to 

 get greenhouse builders and managers to agree. 

 The slope to the south gives the most intense heat 

 and sunlight, but this is generally concentrated at 

 the middle of the day when least needed and poorly 

 distributed during the morning and evening hours. 

 It will generally be found more satisfactory to 

 run the houses of the even span type, especially 

 when built on the ridge and furrow plan, north and 

 south, with the angle of the roof from 40° to 45°. 

 With this construction, the sun's rays strike more 



