538 



DETAILS OF CONSTRUCTION. 



Ventilation at will is insured by simple 

 and effective openings at the ridge. 



This very elegant mode of glazing we 

 have seen exemplified in various places, 

 and are glad to find that Mr Russell, 

 who is at the head of the glass trade in 

 Scotland, is very actively employed in 

 erecting hothouses upon this principle. 

 We believe the idea to be quite original 

 to its inventor, although it very closely 

 approaches the mode of roofing with tiles 

 practised by the Romans, and described 

 by Borgnis in " Traite de Construction," 

 specimens of which are still to be seen 

 in Rome. The hothouses at Alva and 

 at Yester are good specimens of Mr 

 Russell's principle, and we believe he has 

 covered several public buildings in the 

 same way. 



Various modes of glazing. — Glazing 

 without overlaps was, we believe, first 

 brought into notice by Mr Snow of 

 Swinton. The advantages of this plan 

 are " greater neatness, durability, econo- 

 my, and cleanliness, as well as a freer 

 admission of light." For this purpose 

 the glass is cut with perfectly straight 

 edges, which are brought together, edge 

 to edge, instead of being overlapped, as 

 in ordinary glazing. This plan appears 

 to be a great improvement, when large 

 squares of strong thick glass are used. 

 The loss sustained by breakage, in conse- 

 quence of the expansion of water by 

 frost, which is so general, unless the laps 

 are carefully puttied and kept in the best 

 state of repair, is avoided. Again, whether 

 the laps be puttied or not, a considerable 

 amount of light is obstructed, which is 

 completely obviated by this mode of 

 glazing. Should any individual pane get 

 broken, it does not affect the others, as 

 each is independent of the next. There 

 appears, however, to us a difficulty in the 

 great nicety required in cutting the pane 

 to be inserted, so that it shall fit exactly 

 with those above and below it ; for on the 

 correctness of this joining the principal 

 merits of the plan depend. We have 

 tried this mode of glazing, and think 

 highly of it, on account of its more elegant 

 appearance, and, strange as it may appear, 

 its almost total absence of drip. 



As it has been calculated that 10 out 

 of every 60 feet of glazing are taken up 

 with laps, choked with dirt or green 

 muscous matter, and from 18 to 20 



feet with unnecessarily large rafters 

 and astragals, glazing upon Snow's prin- 

 ciple, and using astragals of moderate 

 breadth and increased depth in fixed 

 roofs, will greatly remove this evil. It 

 is useless to talk of rendering the house 

 air-tight by close glazing, whether by 

 this means or by using large squares, 

 and fixing them with leaden laps, as in 

 the Royal Garden at Frogmore. Venti- 

 lation, properly applied, will overcome 

 all this, let the glazing be as tight as 

 possible. 



Glazing, without fore putty — that is, 

 dispensing with the covering of putty 

 usually laid over the edges of the glass 

 in the rebate — has been found an im- 

 provement in some cases. When the 

 glass is laid in the bed of putty in the 

 rebate, and firmly pressed down, leaving 

 the laps one-eighth of an inch broad, 

 instead of covering with putty in the 

 usual manner, lay on two coats of good 

 stiff white-lead paint, about a quarter of 

 an inch in breadth, along both sides of 

 the squares, which, when dry, will keep 

 the glass as firmly in its place as the 

 usual mass of putty applied to the upper 

 sides of the squares. This mode is of use 

 in glazing metallic roofs more than 

 wooden ones, as the absence of putty 

 allows expansion to go on more freely, 

 and thereby saves the breakage of glass 

 from that cause. The paint should be 

 renewed annually ; and if attended to in 

 this respect, the roof will be more free of 

 drip than in the ordinary method of 

 glazing. 



Much too little attention has hitherto 

 been paid to glazing, and we fear the re- 

 duction in cost will not amend this defect. 

 Glass should never be cut too large — that 

 is, fit tightly between the astragals, be- 

 cause the latter are apt to swell when wet, 

 and the glass, being non-elastic, is sure to 

 be broken. If too hard glazed, (as the 

 phrase is,) any violent concussion, such as 

 carelessly pulling down or drawing up 

 the sash, will produce the same effect. 

 Each square should have nearly one-eighth 

 of an inch play between the sash-bars. 

 Another evil is in bedding the squares so 

 that both surfaces do not touch each other 

 at the overlaps ; this is often done through 

 want of skill, and often intentionally, to 

 allow a greater depth of putty in the lap. 

 Now, it were better they w^ere not cross- 



