GREEN-HOUSE STRUCTURES. 105 



will make manifest. The position of the ventilators near 

 the ridge is distinctly marked in this and all the other 

 figures, the dotted lines showing a ventilator raised or 

 open. The position of the benches is also shown. 

 Through the middle there may be either a bench or a 

 solid bed of earth. By use of the scale (one eighth of an 

 inch to the foot) the proportions of the details of this 

 house may be readily obtained. 



The construction of green- houses for private purposes 

 is often very costly and elaborate, the foundation being 

 formed of concrete, stone, or brick ; but after the wall 

 has risen to the surface of the ground, it is found that, 

 unless the wall of stone or brick is very thick indeed, the 

 high temperature and moisture inside of a green-house 

 soon injures the mason work by warring with the low 

 temperature outside, particularly on the north or north- 

 west side. For this reason it has been found that wood- 

 en walls, for ordinary purposes, are equally as good as 

 an eight-inch brick wall for resisting cold, far cheaper, 

 and more durable. 



A common error with the inexperienced is to build the 

 wooden wall of a green-house hollow, filling up the space 

 with sawdust, or some such non-conducting material. 

 The method found best is to sink locust, cedar, or chest- 

 nut posts to the required depth, and at distances of four 

 or six feet apart ; against these (outside) nail common 

 rough boards ; then against these tack asphalt or tarred 

 paper, and against that nail the ordinary weather board- 

 ing. Such a wall will resist cold better than an eight- 

 inch brick wall, and will last for twenty years if kept 

 painted. If a better finish is desired inside, the posts 

 can be hid by weather boarding ; but nothing should be 

 put in to fill the space. When the walls have been fin- 

 ished to the required height, the wall plate to secure the 



