87 



lar, and it will awaken an interest in an extensive class of^-plants that 

 are but little known and that possess a characteristic individuality of 

 form and beauty which, when received in connection with their natural 

 surroundings, can not fail to recall pleasant associations to the mind 

 compared to which the landscape effect produced by a group of flower- 

 ing shrubs will appear exceedingly tame and uninteresting. 



GLAZING GREENHOUSE EOOFS. 



The ordinary method of fastening glass in window sashes is to lay in 

 the glass without a putty bedding, secure it with small triangular bits 

 of tin, then complete the operation by filling the outside of the sash-bar 

 with putty, lapping it slightly over the glass. When this method is 

 applied to greenhouse roofs it causes a great amount of trouble to pre- 

 vent leakage. The presence of moisture, which is almost always to be 

 found on the inside of the roof during cold weather, and the action of 

 frosts and rains on the outside, have a tendency to loosen and destroy 

 the patty, so that an annual overhauling is necessary to keep it in re- 

 pair. But there are now very few greenhouses glazed in the above 

 manner. The old plan has given place to a more permanent and more 

 effectual system so far as regards a tight roof. This plan consists in 

 placing a layer of the best putty on the sash-bar, then pressing the 

 pane of glass until it reaches a firm uniform bed, and so working up a 

 portion of the putty that it will fill all spaces between the edge of the 

 glass and the sash-bar. After the surplus putty is trimmed oif it is 

 allowed to dry for a day or two, which will cause it to shrink slightly 

 from the wood; then a coat of thickish paint is applied, which effectually 

 fills up all crevices and makes a perfectly water-tight finish. No putty 

 is used on the outside, and consequently there is no leakage from its 

 decay ; and instead of tin fastenings the glass is secured by brad-nails 

 three-fourths of an inch in length, four to each pane, fastened at the 

 corners. 



The popular method of roofing glass structures is what is known as 

 a fixed-bar plan. In this plan no framed sashes are used ; the rafters 

 are placed about 8 feet apart, their exact distance depending upon the 

 size of the glass, so that, for a neat job, the glass bar will come in the 

 center of the rafter. Between the rafters horizontal purlines are in- 

 serted to support the sash-bars. The sash-bars are usually made an 

 inch and a half in depth and 1J in width ; these are fastened in paral- 

 lel lines, their distance apart depending upon the size of glass em- 

 ployed; after testing various-sized panes, the size 10 inches by 12 iuches 

 is generally preferred. For this size the sash -bars are placed 12 inches 

 apart, measuring from their centers, allowing one-fourth inch rebate for 

 the glass to rest upon on each side. In setting the panes of this size it is of 

 some importance to place the concave surface uppermost, which makes 



