Glasshouse Building 



221 



Fig. 167. Plumb-level 



between the measured mark and the sighted mark. A rise of 6 in. per 

 100 feet is wanted, so that, supposing the house is to be 100 ft. long, the 

 measured mark should come 6 in. or more above the sighted mark. Sup- 

 pose, for the sake of illustration, it comes 9 in. above; this shows that the 

 ground has a natural rise of 9 in. per 100 feet. Now that the rise of the 

 ground is ascertained, the building may 

 be proceeded with. Take the plumb- 

 board (fig. 166), and against the line 

 as already described put up a row of 

 posts, 5 ft. apart, all the way up the 

 line, and fix them perfectly upright 

 with a batten stay driven into the 

 ground on the inside of the house, and 



nailed near the top of the post. When these are all upright, stand the 

 plumb-board up against each one, and drive in another post on the opposite 

 side, the plumb-board being thus used to give the right distance between 

 the posts. At the same time join the tops of the posts together with a 



short piece of slating batten; one 

 screw to each post will hold it well. 

 There is now a double line of posts 

 all up the trench, perfectly upright, 

 the right distance apart to take the 

 boards and the concrete, and tied to- 

 gether at the top with the batten to 

 keep them from spreading when the 



Fig. 168. Showing Posts at corner of 

 Building, and Boards arranged for Con- 

 crete Walls 



concrete is put in between the boards. The posts are carried round the 

 ends of the house at the same time, and a glance at fig. 168 will show the 

 arrangement of the posts at the corners. 



Prepare a number of little pegs about 15 in. long out of l-in.-square 

 batten, and point their ends; one to every post will be wanted, and two to 

 the corner posts. Get a contractor's level, which is a piece of board about 



