246 On the Glazing of Hot-houses and Conservatories, 



nut must be made to slide in it, to which the trammel is to 

 be annexed by a small pin, round which it turns. The pane 

 is now to be placed with its middle exactly opposite to the 

 bottom of the groove, and its upper edge at right angles to it, 

 and confined in this position by a small piece of wood, of not 

 quite its own thickness, glued to the surface of the board, in 

 a direction parallel to, and touching its side. The diamond 

 being then placed in the trammel, the upper curve should 

 be cut, when without moving the pane, the trammel should 

 be drawn down the groove, till it is brought into the 

 proper position for cutting the lower curve. A reference 

 to the annexed figures will make this description more 

 intelligible. 



In a pane eight inches in width, a curvature of five- 

 eighths of an inch deep in the centre will be sufficient. The 

 glazing is to be executed in the usual manner, except that 

 the panes should lap over each other as little as possible; a 

 lap of one-eighth of an inch is ample, less will do ; and 

 however small the lap, no rain will ever penetrate. In a 

 house glazed in this manner, all the moisture which falls 

 upon the glass, irresistibly gravitates round the circular edge 

 to the centre of the pane, down which it runs in a continued 

 stream, and upon examination, none will ever be found to 

 run down the sides of the putty. From the extreme small- 

 ness of the lapping, no breakage ever happens from frost, 

 and the loss of light occasioned by the film of dirt, which 

 always accumulates between the panes, is much lessened. 



Those who prefer a close house, may bed the panes with 

 putty between them, taking care to insert a narrow piece of 

 smooth and thin wood previously, at the centre, which being 



