S T 



560 



S TO 



is desired, the latitude being 51° 31% | Mr. Seymour, gardener to tlie Count- 

 and the sun's declension then 16° 36^ j ess of Bridgewater, at Ashridge Pari<, 



nortli, therefore the roof ought to slope 

 at an angle of 34"-' 55'. 



Fig. 157. 



has these sensible remarks upon the 

 subject: — 



" There ought to be three or four 

 sizes of panes used in horticultural struc- 

 tures ; suppose, for example, the largest 

 size for vineries, peach, and fig-houses ; 

 the next for pits for growing pines, 

 melons, and cucumbers; a third size 

 for frames; and the smallest for hand- 

 glasses. If the sizes are so arranged, 

 they will be found economical by the 

 saving of glass. When there is a gene- 

 ral repair going on with the hot-houses, 

 the glazier ought to begin with that in 

 which tlie largest sized panes are first, 

 and work down to the smallest, and not, 

 as is freejuently the case, cut a large 

 piece of glass away to replace a small 

 one. In my opinion, there are no better 

 sized panes for hot-houses than seven 

 inches wide, by four and a half deep ; 

 for pits, by three inches deep ; lor 

 frames, five and a half by two and a 

 half inches deep, &:c., with a lap of one- 

 eighth of an inch. The glass should be 

 clear, stout, and selected as flat as pos- 

 sible, so that the panes may lie perfectly 

 level one upon the other, and so cut 

 being vertical. The asterisk d points that they may not fit too tightly against 

 out its position at the equinoxes, and Ej the ribs, (which is frequently practised 

 its position at midwinter. If the best by some glaziers,) but room'should be 

 glass be employed, it is an excellent i left for the ribs to swell and expand, 

 plan to have it put double in each sash. Before a light is glazed, all the panes 



In latitude 52°, Mr. Knight found 

 from lengthened experiments, that the 

 best angle is about 34°, considering the 

 services of a hot-house through the year, 

 and to illustrate this, he gave the pre- 

 ceding diagram. About the middle of 

 IMay, the elevation of the sun at noon 

 corresponds nearly with the asterisk 

 A ; in the beginning of June and early 

 in July it will be vertical at b, and at 

 midsummer at c. only six degrees from 



an interval of half an inch being left 

 between the two panes, and a small 

 hole at the corner of the inner one to 

 prevent the glass being broken by the 

 expansion or contraction of the air be- 

 tween. This confined air is one of the 



should be laid in loose, to see that they 

 fit easy and are quite level, as well as 

 range one with the other; when that is 

 done, the panes must be taken out and 

 some well worked putty laid in the re- 

 bate, the panes must then be replaced 



worst possible conductors of heat, keep- I and pressed firmly down, and the bot- 

 ing the house from being rapidly cooled torn frame bedded in the puttv, so as 

 during the coldest weather, and thus is not to leave a vacancy. When the glass 

 effected a very great economy of fuel, is bedded in the putty along the astra- 

 ■whilst little or no interruption is caused gals, the usual way is to ' front puttv' 

 to the entrance of light. — Princ. of the whole at once ; but at Kew, the 



Gard. 



Glazing, or the mode in which the 

 glass is inserted in the frames, is a very 

 important consideration ; for if done 

 imperfectly, moisture from rain, dew, 

 or vapour condensed within the house 

 penetrates between the rebate of the 



lights are put by after the glass is bed- 

 ded till the bedding putty is dry. The 

 astragal then gets a coat of paint, and 

 also a strip of the glass, the depth of 

 the bedding on the astragal, and when 

 this is dry the front putty is put on. 

 The coat of paint on the glass will cause 



frame-work and the glass, or between the front putty to adhere to the glass, 

 the laps of the panes themselves, and and it will remain sound many years 

 «»-„„„j;„„ ;„ .i,„ „„t „(• c :.,_ ..^c^:\ i »i . i •» ■ . -.i 



expanding in the act of freezing unfail 

 ingly cracks them. Again, if the p: 

 fit tightly into the rebates, any sue 

 expansion causes a similar fracture 



_-,- ^ _ ^ longer than when it is put on without 



ingly cracks them. Again, if the panes , this precaution. This is a capital con- 

 fit tightly into the rebates, any sudden trivance for lights that slide up and 

 «.,^o,.„; „„„ „ „;™;i„. r.„„. — , down J but for lights that are fixed, the 



