GLAZING. Numerous systems of Glazing have, of late years, been invented and patented, all being chiefly directed against the use of putty, and professing to offer advantages over the ordinary method, such as cheapness in construction, durability, the admission of additional light, and special facilities for repairing broken glass. Although some of these methods are largely adopted, and answer well in the case of extensive glass buildings, their use for horticultural purposes is by no means general. One of the best patent systems introduced is that known as Rendle's, in which the panes of glass are fitted at the top and bottom into horizontal grooves formed of bent zinc, and are slightly lapped on each other at the sides. The zinc grooves are made to conduct the water down the roof from the outside, and also that caused by condensation underneath. This renders the structure remarkably free from drip inside, which is an important consideration. No putty is used, and the plan answers equally well either with straight or curvilinear roofs, the glass being kept in place by indiarubber wedges. Various other modes are recommended by different makers, some having strips of felt along the sides of the panes, and a metal ridge on each rafter, screwed on the felt sufficiently close to hold all firmly underneath. The use of putty is requisite with sashes that are movable, either as ventilators or for covering frames, to prevent the glass shaking out or becoming displaced. In Glazing, the panes may vary in size, according to the dimensions of the house or pit. Unless the roof be very flat, the laps should not exceed 3/8in., and they should be made as airtight as possible, each pane being secured in position before the putty is put on by small pieces of zinc made for the purpose. The larger the panes are, the more light do they admit; but a length of 2 1/2ft. or 3ft. must be an outside limit, with a width not much exceeding 1ft. Great pressure is put on the surface of glass houses by rough winds, and by snow in winter; and, in order to withstand this, the quality of the glass and proper Glazing must be insured in the first instance.