GLASS STEUCTUEES AXD APPLIANCES. 



G H, external air passes through c into the ventilator, 

 and after being warmed to about 90^ enters the 

 house ; at k is an evaporating trough, rendered hot 

 by means of the circulation through the ventilator, 



ventilating plant or fruit houses this is very satis- 

 factory, especially when the hot-water pipes are well 

 furnished with steaming-trays. 



Thomsoii's Hot Air Ventilator (Fig. 82) although 

 originally constructed for warming the air on its 

 way into Vineries, is equally well adapted to all kinds 

 of fruit or plant houses where tender exotics require 

 careful ventilation in cold weather. Mr. Thomson 

 says : '* This apparatus consists of a sheath of copper 

 placed over a row of the front pipes. The diamet,cr 

 of this sheath is one inch more than the hot pipe it en- 

 closes, consequently there is an open space of half an 

 inch all round the pipe inside the sheath. This 



O' 



b 

 o 

 o 



Fig. 81. 



Fig. 83. 



Fig. 80. 



-Weeks's Hydro-caloric 

 Ventilator. 



Fig. 82.— ■'.Varin Air Casing for Pipes. 



and by keeping this either charged or otherwise, hot 

 air moist or dry is obtained at pleasure. A two-inch 

 pipe, leading direct from the main, renders the venti- 

 lator efficient, while the ordinary heating apparatus 

 remains cold. 



A simple and efficient mode of warming the 

 entering air before it comes in contact with the plants 

 in stoves will be found in Fig. 81. To prevent a rush 

 of cold air into the house through the ordinary 

 ventilators, a, the hot-water pipes are enclosed in per- 

 forated zinc, B, which being made hot by its proximity 

 to the pipes, causes the air which passes through it to 

 divide into a gentle stream on its way to the body of 

 the house. Another stream of hot air passes up at 

 the back of the table d, which is solid, and entering 

 at c, protects the plants nearest the glass from 

 the ill-effects of cold. As a cold- weather mode of 



cavity is fed with fresh air from the exterior^ of the 

 house by a pipe five inches in diameter, which springs 

 from the lower surface of the sheath, and passes 

 through the front wall of the house to the external 

 air. There is a valve in this feed-pipe to modify the 

 supply of fresh air at pleasure. In the upper surface 

 of the sheath is a double row of small holes, so that 

 the moment that the cold air comes into the chamber 

 round the pipe, and gets hot, expanded, and lighter, 

 it makes its exit through these holes into the general 

 atmosphere of the house." 



The Amateur's Ventilator. — The amateur 

 who builds a small green-house or Vinery upon 

 strictly economical principles, and docs not wish to 

 incur the expense of ventilating gear for so small a 

 structure, may adopt the older system of opening 



