INDEX. 365 



Difficulty of managins^ the atmosphere in large, dome-shaped houses. — 

 Covering necessary. — To equalize the temperature. — The natural law of 

 equality ineffectual. — The slightest cause disiurlis the equilibrium of the air. 

 — The extreme sensibility of the air. — Irregularity of its temjjerature in hot- 

 houses. — The causes of this irregularity. — Experiments of Gay Lussac — 

 of Rudberg, 275 



A new method of ventilation. — Adapted to lean-to houses. — Figured and de- 

 scribed. — Facility with wliich this method may be wrought, 277 



Method of ventilating span-roofed houses. — Adopted in the new hot-houses 

 at Frogmore. — Figures and description of this method, . 279 



Methods of airing by the rachet wheels. — By springs. — Superiority of the 

 former. — Necessity of having the machinery for ventilation properly erected. — 

 Its liability to get out of repair. — Method applauded without merit. — Neces- 

 sity of guarding against the applauded inventions of any one, 230 



SECTION IV. 



MANAGEMENT OF THE ATMOSPHERE. 



Atmospheric motion. — Admitting large quantities of cold air. — The results 

 of this method. — Questions arising out of these considerations. — The quantity 

 of air to be admitted. — Motion affected by various circumstances. — The 

 atmosphere of a hot-house influenced by the glazing of the sashes. — Effect 

 produced by radiation. — Growth of plants in Wardian cases. — Deterioration 

 of air by flues, &c., 234 



Method of airing without opening the sashes. — Figured and described. — 

 This method recommended for houses during cold weather in winter, . . . 238 



Common method of ventilating figured and described. — Evils resulting from 

 this method — Action in cold weather, 290 



Contrivance for admitting warmed air into the house over the heating appa- 

 ratus. — By a serpentine conductor. — Size of the tubes necessary. — Radiation 

 of heat from the surface of the flue. — The effects of the external air neutral- 

 ized by this method, ^ 292 



The system of ventilation, — Its object being to prevent a stagnation in the 

 atmosphere. — Evils of this method shown and explained. — Mechanical and 

 chemical effects of ventilation, 293 



SECTION V. 



CHEMICAL COMBINATIONS IN THE ATMOSPHERE 



OF H OT-HOUSES. 



Nourishment plants ought to receive from the atmosphere. — How to receive 

 it. — Starch and su^ar. — Their different properties. — Questions arising from 

 considerations of their properties. — Experiments on the atmosphere. — The 

 importance of oxygen to vegetable life, 296 



Atmosphere from fermenting manure. — Quality of heat generated by it. — 

 Impregnation of the atmosphere with ammonia. — Experiments on the atmos- 

 phere of a green-house with ammouiacal gas, 299 



Composition of ammonia. — Excess of ammonia. — Its suffocating influence. 

 — Illustrations of its effects. — Fumigation of plant-houses and pits with 

 ammonia. — The cause of luxuriance in plants. — Produced largely from fer- 

 menting manure, &c., 1 300 



What guides we have to ascertain the various changes in the atmospheric 

 elements. — Disagreeable smell on entering a hot-house. — The cause, and how 

 to remedy it. — The important part played by oxygen in this process. — Pro- 

 portion of oxygen necessary to vegetables. — Amount contained in atmospheric 

 cir and water. — .4ffinitv of its elements 303 



