548 



DETAILS OF CONSTRUCTION. 



Fig. 783. 



The sash-bar used by Sir Joseph Paxton 

 in his ridge-and-furrow houses, prior to 

 the building of the great 

 conservatory, are excellent. 

 Fig. 783 is a section, full 

 size, of those used in the 

 roof — those for the upright 

 or front sashes being 

 simply a little thicker. 

 From the way in which 

 they are bevelled off below, 

 it will clearly appear how 

 little light they intercept. 

 The grooves in which the 

 glass is set prevent the 

 wet from getting in, and dispense with 

 the use of putty as an external cover- 

 ing, none being used except the least 

 possible quantity, to bed the glass in the 

 grooves. Similar astragals, but of a larger 

 size, have been used by Sir Joseph Paxton 

 in the Crystal Palace roof. 



The astragal we use, fig. 778, is very simi- 

 lar ; only one groove in each bar is about 

 one-third deeper than in the other, to faci- 

 litate the introduction of the glass in cases 

 of repairs, which could ■ not so easily be 

 effected if both grooves were of the same 

 depth. In fitting in the square, it is in- 

 troduced into the deep groove first, and 

 then slightly drawn back until it has an 

 equal bearing on each astragal. By this 

 mode of glazing, no putty is exposed to 

 the weather, which is a vast improvement. 

 Since the use of large glass has become so 

 general, and rafters and framed sashes 

 have been almost dispensed with, we use 

 much larger astragals, and place them also 

 much farther apart. 



Within these few years, considerable 

 improvements have been made in hot- 

 house-building, so far as astragals and 

 rafters are concerned. The repeal of the 

 duties on glass and timber has so much 

 lowered their price, that now, in fact, 

 labour is the chief item of serious expense ; 

 and we hope the day is not far distant 

 when that will be considerably abridged, 

 by the discontinuance of ponderous and 

 expensive rafters, and costly framed sashes, 

 the manual labour upon which has been 

 in many cases equal to, if not more than, 

 the whole value of the material. 



As roofs are now so generally made 

 fixtures, we have little more to do than to 

 calculate the expense of astragals, wall- 

 plates, and ridges, which are estimated for 



by the lineal foot or yard. These are all 

 the details necessary for well constructed 

 roofs, except in the case of houses of very 

 extraordinary dimensions, where rafters 

 or purlins, either of wood or metal, must 

 be introduced to give greater [strength to 

 the roof. We can only look to mechanical 

 aid in this respect ; and, as a first and ex- 

 cellent beginning, we have for some years 

 had a beautiful and efficient machine for 

 making astragals, the invention of Sir 

 Joseph Paxton of Chats worth, figured and 

 described by him in " The Transactions of 

 the Society of Arts," vol. liii., part 1. In- 

 stead of describing this invention, we may 

 remark that it has, with some improve- 

 ments, been for some years in use in the 

 extensive establishment of Messrs Mont- 

 gomery of Brentford, and, with various 

 modifications, in other places about Lon- 

 don, where astragals of all sizes and qua- 

 lities can be purchased by the lineal foot 

 or yard. Such, therefore, as intend to 

 build hothouses, in whatever part of the 

 kingdom, have only to send the dimen- 

 sions, and they will be supplied with them 

 ready to fit up. 



Mr Birch, of the Phoenix Sawmills, 

 Regent's Park, has further improved the 

 sash-bar cutting machine, and furnished 

 with it the whole of the bars used in the 

 Crystal Palace. His improvement con- 

 sists in the addition of a second set of 

 cutters, whereby the sash-bars, instead of 

 passing twice, pass only once under the 

 formidable claws which give to them their 

 proper form ; thus doubling the amount 

 of work performed in a given time, or at 

 ordinary work producing 2f miles of 

 finished bars per day, with only the man- 

 ual labour of one man and a boy. Mr 

 Birch has also another machine in opera- 

 tion for cutting ridge-bars, which are 

 finished in 24-feet lengths, and cut out 

 of deal 3 inches square, producing 2400 

 lineal feet in ten hours. Nor are these 

 important adaptations of very simple ma- 

 chinery confined to the cutting off the 

 astragals to their proper lengths ; they 

 embrace also the giving them the required 

 bevel at one end, and the shoulder at the 

 other : even the nail-holes are perforated at 

 each end, for fixing to the gutter and ridge. 



As ridges and gutters have now taken 

 the place of rafters, it may be as well to 

 allude to the "Paxton gutter" here. The 

 original gutters used by that intelligent 



