GLASS STRUCTURES 103 



against the ridge pole, which leaves the shutters clear 

 for the water to run off. They are made of second fencing 

 matched and dressed. 



"In this house there is glass over the path, which is not 

 necessary in the lean-to plan, shown in Fig. 39, where the 

 sash is all on the south side of the path. It is important 

 to have crops grow as close to the glass as may be, and this 

 fact should be carefully borne in mind. This style of 

 house is susceptible of many modifications. It may be 

 used as a lean-to on the south side of the dwelling, where 

 it may receive a little heat from the house. Its limitations 

 are about the same as those of hotbeds. When such a 

 house is intended for use in winter, it might be an advantage 

 to so plan it that the manure from one-half could be renewed 

 every five or six weeks." 



GREENHOUSES 



Greenhouse is a term applied to glass structures of the 

 larger sort having special heating apparatus and used 

 for growing plants. Interest in the greenhouse growing 

 of plants has increased very materially in the last few years, 

 and there are many gardeners who manage from a few 

 thousand feet of glass up to several acres. 



The advantages of greenhouses over hotbeds lies in 

 the ease of working and of controlling climatic conditions 

 under them as compared with hotbeds. They are easier 

 to heat, and if installed with the Skinner irrigation system, 

 are easier to water. They represent a very much greater 

 investment than hotbeds, but two or three more crops can 

 be taken off than is possible with hotbeds. Well managed, 

 a greenhouse can be used at least ten months of the year. 



Types. There are at least three distinct types of houses 

 as regards construction: lean-to, even-span, and three- 



