62 GARDEN FARMING 



the wider spacing. By placing the sash bars 16 inches apart and 

 using a 12 x 16 inch glass, the construction is made cheaper than 

 when a 16 x 24 inch glass is used, and the same amount of 

 framework is necessary in either case. The only feature which 

 adds to the obstruction of light in the use of 12 x 16 inch glass 

 is the extra lap which is necessary in the middle of each section. 

 The 1 6 x 24 inch glass brings the laps 24 inches apart, while the 

 12 x 1 6 inch glass brings them only 12 inches apart. 



For the roof of a. greenhouse or forcing house the glass should 

 be laid on the same plan as are shingles ; but instead of a long lap, 

 as in the case of shingles, a very short one should be made. A 

 proper width for a lap is from | to ~ inch. Wider laps collect 

 dirt, obstruct the light, and are much more apt to cause breakage 

 by the freezing of moisture between the laps. 



Laying the glass. Greenhouse glass should always be bedded 

 in putty ; that is, the putty should be placed in the groove of the 

 sash bar and the glass pressed into it instead of on top of the 

 glass, as is customary in ordinary glazing. 



The old and reliable lapped-glass roof for greenhouses will 

 probably never go out of fashion, but the cost of laying it and the 

 tedious method usually employed have induced many to seek a 

 substitute in other styles, such as the " butted " and zinc strip. 

 The following method of laying lapped glass is so simple and so 

 easily mastered, by even an unskilled laborer, that it cannot fail to 

 meet a much-felt want : If the work is to be done during cool 

 weather, which is not desirable, choose a warm room, and upon a 

 table about 2 feet high arrange a board much like the kneading 

 board used by a pastry cook. This should be wide, smooth, and 

 perfectly flat. Warm a quantity of putty, say 5 or 8 pounds, suffi- 

 ciently to make it soft and pliable, but not sticky. With the hand 

 spread the putty over the board in a layer of uniform width and 

 of a length as great as that of the glass to be used, and with a 

 section of 3- or 4-inch vitrified sewer pipe, as a rolling pin, roll 

 the putty into a thin layer about T 3 g inch thick. Then with the 

 glass held as shown in figure 19, that is, with the ends firmly 

 grasped in the hands, the convex side turned away from you and 

 the edge about J inch back from and parallel with the edge of the 

 putty, press the glass through the putty so as to cut off a narrow 



