90 



GREENHOUSES 



the sill, which is bored to fit over the posts 

 and bolts and is secured with nuts. No 

 posts are set in the end walls, but the bolts 

 are set the same as in the side walls and are 

 used for the same purpose. 

 In some cases the posts are 

 set in the ground and the side 

 walls are constructed of two 

 layers of matched lumber. 



The purlin posts and other 

 supports are put in position 

 much the same as in the wood 

 frame house, except that in- 

 stead of being embedded in 

 concrete, they are sometimes 

 provided with foot pieces and 

 rest on small concrete piers. 

 Split malleable iron castings 

 may be had in almost every 

 conceivable form for joining 

 the frame together. These arc 

 fastened by bolts and set screws, so that it is 

 not necessary to thread the pipe. The sash 

 bars are fastened to the pipe purlins by 

 means of U-shaped clips or pipe-straps, 

 which are secured to the bars by means of 

 screws. Purlins are usually made of one and 



Fig. 51. Struc- 

 tural steel post 

 with board 

 wall 



