On glazing Hot-houses^ Pits, Frames, 4r. 121 



Perhaps it would be better to scatter a few tie-bricks in every 

 course. Would the apertures in a garden wall so constructed 

 tend to reduce the heat which would be given out by a solid 

 garden wall at night, to the advantage of the trees ? 



The plan of this wall originated wilh Mr. Wm. Denyer, 

 market-gardener, at Battle, Sussex, and late gardener to Lady 

 Webster of the same place. 



Dartford Nursery, Dartford, Dec. 9. 1837. 



Art. V. On glazing Hot-houses, Pits, Frames, Sfc. 

 By A. Forsyth. 



Havinu lately examined the glass roof of an ill-constructed 

 new green-house, I found nearly one half of the glass more or 

 less cracked by frost. The laps of the glass, not being filled with 

 putty, allowed the water to lodge there ; and, as soon as frost 

 congealed the water into ice, the squares of glass cracked by the 

 expansion of the water in the process of freezing. That frost 

 breaks glass in this manner, gardeners generally are well aware 

 of; yet, so recently as 1836, and in the very suburbs of London, 

 I met with unbelieving brethren, even on this important point, 

 whom I undeceived by calling their attention, one frosty evening, 

 to the metallic roofs of some unprotected cold frames ; when 

 the sound of breaking, and the sight of the broken squares, satis- 

 factorily convinced the most sceptical. Now, to prevent this 

 great and unnecessary expense in repairing, and also to prevent 

 cracks in the glass, which always let in water more or less, either 

 the inside temperature must be so high (as is the case with 

 stoves), that the water between the laps of the glass may not be 

 allowed to freeze ; or the laps must be rendered water-proof; to 

 accomplish which, in a manner at once cheap, simple, and satis- 

 factory, I propose the lap shown in Jig. 19., and which is to be 



19 _ 



Breadth of lap three eighths of an inch. 



a, Upper edge of lower square. c, Lower edge of paint. 



b. Lower edge of upper square. d, Upper edge of paint. 



puttied and painted. The sashes are glazed with rectangular 

 quarries of glass, overlapping each other about three eighths of 

 an inch, with the space between, grouted with soft putty, in the 

 usual way ; then, in painting, in.stead of doing all the putty 

 except that which stands in greatest need (viz. that between the 

 laps), let the joinings of the glass, both the imder lap and over 

 lap, be carefully painted ; but, in doing the upper lap, let the 

 upper edge of the paint run in the direction of r/c, thus carrying 



