786 ANNUAL REPORT OF THE Off. Doc. 



are grown for the London, Paris, Berlin, Vienna and St. Petersburg 

 markets, boards are largely used in conjunction with glass in the 

 construction of roofs of greenhouses in that country. By the use of 

 boards there is a great saving, not only in the construction of a 

 greeohouse, but in the heating of same in the winter season. 

 A greenhouse with a roof built of boards, or partly so, will retain 

 the heat much longer than will one covered wholly with glass, and 

 the desired temperature can be maintained at much less cost 

 for fuel. We are assured by those who have seen the Palms grow- 

 ing under conditions as above stated, that no plants could be more 

 luxuriant or healthy. At the price glass was selling in September 

 (1901), namely -17.28 per box of fifty square feet, a great saving could 

 be effected in this country by the method referred to. Glass fluc- 

 tuated very much last year; for instance, in September, |7.28 was the 

 price per box of fifty square feet, whereas, in November, the same 

 quality of glass could be bought for |4.55, and twenty years ago $2.00 

 per box was about the price. 



It will be understood that what is said here is merely sugges- 

 tive, that much latitude is allowed in the selection of a site for a 

 greenhouse establishment, according to what is to be grown 

 and the available ground to be used; and also in the selection 

 of the material to be used in the building, many believing that as 

 much iron or steel as possible should be used so as to have them as 

 nearly indestructible as such structures can possibly be made. 



HEATING. 



After the water supply has been determined upon and the ques- 

 tion of drainage and aspect duly considered, another serious matter 

 to occupy the attention of those desiring to go into the greenhouse 

 business, is the different methods of heating, because, generally 

 speaking, quite early in the operation a hole in the ground has to be 

 dug, known by the old-school gardener as a "stoke-hole." Though 

 some of the very largest and up-to-date commercial concerns, where 

 steam is used as the heating medium, do not advocate digging a hole 

 in the ground at all, but by placing the boiler or boilers at the low- 

 est point naturally, according to the lay of the land, and by em- 

 ploying a small, though a separate and independent steam-boiler, 

 which is so constructed as to work automatically and thus pump 

 the condensed water back to the boiler. In a small way, however, 

 Miat plan of operation would seem to be out of the question, the 

 water returning by gravitation being the most practical. 



Generally speaking for small establishments, it is better to dig a 

 hole, whether the heating be done by steam, hot water, or the old- 



