MARKET GARDENING UKDER GLASS. 99 



forcing houses the cost must naturally vary more or less 

 in different localities on account of labor and material, 

 the method of building and the finish put upon the 

 houses. Estimates for the construction of such houses 

 are within the reach of every gardener, including all the 

 appurtenances to make the houses complete for use. 

 Every horticultural journal gives, in its columns, the 

 addresses of persons whose business it is to build houses 

 of this description, and all other designs now in common 

 use by practical, commercial gardeners. In the same 

 journals can be found advertisements of all the leading 

 manufacturers of heating apparatus. 



The approximate cost of a vegetable forcing house, 

 erected upon system No. 1, dimensions 30x250 feet com- 

 plete, will not exceed $4,500. This comprises cost of 

 boiler, hot and cold water pipes, about $1,700, and the 

 pipes and cocks for watering about $100 more. Such a 

 house may be heated by hot water carried in three lines 

 of three-inch pipes running around under the side tables, 

 or it may be heated by steam, the water being forced by 

 natural circulation. This amount of heating surface is 

 quite sufficient to keep tlie house at a temperature rang- 

 ing from 40° to 50° during .the most severe weather of 

 mid- winter. In fact, all that is really necessary the 

 coldest nights is to have heat enough to keep frost out 

 of the house. In growing and forcing vegetables in 

 winter there is nothing gained by having the tempera- 

 ture higher than here indicated. It is, on the contrary, 

 detrimental to the healthy and vigorous growth of 

 plants. In the latitude of Philadelphia it will take 

 about fifteen tons of coal to heat a house of the size 

 described during the cold months. The aim, in past 

 days, to get a high temperature in forcing houses, was 

 one of the serious and expensive mistakes made by gar- 

 deners when such structures were first substituted for 

 hotbeds and cold frames. The want of success and, at * 



