60 MASSACHUSETTS HORTICULTURAL SOCIETY. 



advise the beveling of the lower edge, so as to reduce as much as 

 possible the exposed surface of this stick, to which the moisture 

 would be liable to freeze, causing ice to back up under the edge of 

 the lower lights of glass and break them. 



Next in order comes one of the most important details of the 

 house, the roof glazing bars, or as they are generally called, the 

 "sash bars." The object of these bars is to support the glass, 

 and for this purpose a light section of lumber only is required, its 

 dimensions being governed by the length of the bars to be used 

 without the assisting support of a purlin. I find in ordinary 

 practice, assuming that sixteen-inch by twenty-four-inch glass is 

 being used, for bars having a distance of about five feet between 

 supports, one and three-fourths inch by one and one-eighth inch is 

 ample, and for those whose supports are eight feet apart, two 

 and one-fourth by one and one-eighth inch is well suited, having 

 ample strength for the strain brought to bear upon them, and yet 

 being of such dimensions as to cast but little shade. These bars 

 should have on their upper edges suitable rabbets for the reception 

 of the glass ; the bottom of these rabbets being made in the shape 

 of a V as a receptacle for the putty necessary in glazing. A 

 groove is also run in each side of the bar to carry off the water 

 caused by the warm, moist air of the house striking the cooler 

 glass surface and condensing, and thus preventing its falling on 

 the plants and causing injury. 



I wish here to call your attention to two very important points 

 to be considered in designing or erecting greenhouse structures : 

 first, avoid as much as possible any detail which will throw 

 shade, and, second, avoid all recesses, mortises, or other places 

 where moisture may find lodgment. Both of these items are of 

 the utmost importance, yet are generally overlooked by the novice 

 in greenhouse building, and I am sorry to say are often neglected 

 by older heads, particularly the latter items, — mortises or other 

 places for lodgment of water. If you desire to use bars which 

 are provided with the groove on each side for the carrying off of 

 the waters of condensation, as just described, be sure that the 

 outer sides of this gutter or groove at the lower end are cut away 

 so as to allow the water to drop out just before reaching the 

 eaves plate, or glazing strip, or entering any joint which may have 

 become opened from various causes, thereby producing premature 

 decay. Tliis small feature of cutting condensation grooves at the 



