GLASS STRUCT CEES AXD API LIAXCES. 



213 



Glazing with Putty. — Previous to the re- 

 moval of the tariff on glass the squares were ex- 

 tremely small, and the sash-bars, or astragals, were 

 so closely placed as to greatly interfere with the free 

 passage of light ; moreover, those made of deal were 

 much heavier than is now considered necessary, 

 notwithstanding the fact that much larger and 

 thicker panes are now used. Add to this the 

 numerous laps choked with dirt, or perhaps carefully 

 closed with putty, for the twofold purpose of ex- 

 cludiug cold air and preventing didp, and it is by no 

 means difficult to imagine a roof of the worst descrip- 

 tion that could be devised for horticultural purposes. 

 In such a roof it has been calculated that every 

 100 ft. of glaziug presented. from 25 ft. to 30 ft. of 

 opaque sui-face, thi'ough which not a single ray of 

 light could penetrate, i'ully alive to the disad- 

 vantages under which they laboured, horticulturists 

 introduced iron, copper, and zinc for sash-bars ; but 

 these materials did not greatly improve matters, as 

 may be gathered from Fig 32, which is drawn from 

 a portion of a light still in existence, made seventy 

 years ago. At that time glazing without fore-putty 

 had not been thought of ; yet, when thoroughly well 

 bedded, which is the great secret of putty- glazing, 

 and two coats of good white-lead paint are laid on 

 each side of the square, from one- eighth to a quarter 

 of an inch broad, the first step towards improvement 

 has been secured. One of the great evils of fore- 

 puttying is the predisposition to drip, which is 

 brought about by the constant pressure of moisture 

 behind the putty when it begins to part from the 

 tongue of the sash-bar, as it soon will when used of 

 inferior quality, or if the wood is not dry and well 

 seasoned. Once let iuto the 'bed, the wood swells, 

 and frost causes the putty to expand, when, the 

 glass being non-elastic, it natm-ally breaks under the 

 great pressure. Of equal value is this omission of 

 the fore-putty on metallic roofs, as expansion goes 

 on more freely over every part of the bar, and there 

 being no decapng matter to prevent it, water passes 

 quickly away. 



Metallic roofs were at one time greatly condemned 

 on account of the loss from breakage ; but this arose 

 from what is termed hard glazing, that is, cutting 

 the glass too large for the openings. This part of 

 the mechanic's business is now better understood, 

 and where one-eighth of an inch of play is left on 

 each side, breakage is not more frequent in roofs of 

 metal than of wood. It may not be out of place to 

 mention that mineral or anti-corrosion paint used as 

 a priming coat for preceding glazing has, in my own 

 experience, proved greatly superior to lead of the 

 best quality, and being cheaper it is worthy of ex- 

 tended use. Some twelve years ago a Peach-house 

 was primed with it ; the squares (14 in. by 20 in.) 



were well bedded, but not fore-puttied, and everv 

 part of the roof is still sound and free from drip. 

 Since that time the roof has received the triennia I 

 course of oil and lead painting, and every inch of 

 sash-bar is as firm and good as it was at the end of 

 the first year. 'WTien anti- corrosion paint is useci 

 it seems to penetrate the wood like creosote, and 

 to become part and parcel of the fibre, from which 

 it never separates. The drawback, in the first 

 instance, is its roughness of surface, but this becomes 

 plain and smooth after it has received one or two 

 coats of oil paint. 



Modern Glazing.— For some time after the 

 tariff was removed, horticulturists, at all times very 

 anxious to get rid of perishable facing, were un- 

 decided as to the best mode of accomplishing this 

 object. Manufacturers commenced supplying them 

 with an article imperishable, except by fracture, at 

 a price for quantity and quality truly surprising, and 

 all lovers of gardening began to indulge in the pos- 

 sible luxury of a bit of glass. Market gardeners, 

 private growers, and nurserpnen saw their way to 

 rapid extension ; but the builders, for the nonce, 

 found themselves nonplussed by the producers. A 

 good article was placed within their reach, an arti- 

 cle which would enable them to set the elements at 

 defiance, as they could bring the vegetation of the 

 Antipodes to grow and flomish at their very doors ; 

 but the perplexing problem, "How are we to ajDply 

 it so as to get rid of this perishable oil and chalk ? 

 presented itself. The constant hacking out of a 

 broken square, often involving the fracture of two 

 more in the performance of the ojDeration, began, 

 however, to quicken men's brains, with the usual 

 result, and systems of glazing innumerable, some 

 good, some bad, sprang into existence. The life of 

 some was fleeting, as they possessed no practical 

 value. 



That many of these inventions are a great advance 

 there can, however, be but little doubt, and we will 

 endeavour to notice as many of the best as the limits 

 of these pages will allow. 



BearcVs Si/stem.— One of the most important moves 

 in a new direction is the system invented and pa- 

 tented by Mr. Beard. It has now been in use for 

 some time, and forms the keynote on which other 

 inventorsand manufactm-ers have played; the object 

 in every instance being a maximum of light, com- 

 bined with a minimum exposure of perishable mate- 

 rials to the action of the elements. It possesses 

 several advantages which the ordinary mode o£ 

 glazing with putty does not offer, and one of the 

 most important is the facility with which the whole 

 of the glass can be taken out and put in again, 

 should it be found necessary to remove the house. 



