GKBEN-HOUSE STRUCTURES. 57 



gases, so troublesome with flues ; besides, it is an immense 

 saving of labor, more particularly if the green-houses are 

 extensive. In our establishment, covering over an acre 

 with glass, but nine boilers are used, involving the work 

 of only nine fires. If we heated by flues, not less than 

 forty fires would be necessary, and at least three times 

 more labor would be required. 



Fig. 16 is the end view and fig. 17 the ground plan of a 

 Hot-house, or Forcing House, erected by us last season, 

 mainly for the purpose of forcing flowers in winter. This 

 house has given us the highest satisfaction, and for the pur- 

 pose of a conservatory for winter blooming plants, we be- 

 lieve it will be found to be most suitable. So satisfied were 

 we of the practicability of this style of house for this pur- 

 pose, that we erected it of mammoth proportions, 300 feet 

 in length by 20 wide inside. It will be understood by the 

 sketch, that the roof is stationary, the whole slope front- 

 ing south, 15 feet in length, being one unbroken sheet of 

 glass. The back slope to the north, 8 feet in length, is 

 also fixed, but in that there are movable sashes 3 feet 

 square every 9 feet, for the purpose of ventilation, or about 

 one-sixth of the whole roof facing north. The movable 

 sashes are hinged at the top, and are lifted by an iron 

 bar fixed to the lower edge, in which holes are punched 

 every 4 inches, so that the ventilation may be graduated 

 to suit the weather. This amount of space for ventilation 

 on the roof would be entirely inadequate alone, and it is 

 one of the most common errors in building fixed roof 

 green-houses or graperies, to have insufficient means for 

 the escape of the excessive heat generated by the sun's 

 rays in May or June. 



But this difficulty is easily and cheaply overcome by 

 admitting air from sliding shutters made in the front wall. 

 The size and width apart of these must depend upon the 

 dimensions of the green-house. In the house above re- 

 ferred to, we have them made 18x24 inches, placed in the 

 3* 



