74 GARDE JTI^G FOR PROFIT. 



or about $10 per running foot. The structure is very 

 simple. The walls front and rear are constructed of 

 cedar posts, about five to six inches in diameter, placed 

 four feet apart and sunk three feet in the ground. On 

 the outside of these are nailed rough hemlock boards, 

 against which a layer of asphalt or tarred paper is tacked, 

 over which is nailed the ordinary weather boarding. Such 

 a wall will resist cold better than an eight-inch brick 

 wall, and will last twenty-five years if kept painted. A 

 very common error is to build the wooden wall of a green- 

 house hollow and fill the space with sawdust. This 

 should never be done, as it is more expensive, and is by 

 no means so good as the plan here given. It will be 



. 10. CROSS-SECTION OF FORCING-HOUSE. 



seen by the engraving, figure 10, that these greenhouses 

 of Mr. Hudson's are heated with hot water, the six O's 

 in the engraving representing six runs of four-inch pipe, 

 which is sufficient to give a night temperature of forty- 

 five or fifty degrees when the thermometer is ten below 

 zero, which is a sufficient night temperature in the win- 

 ter months for growing such crops as Lettuce and Rad- 

 ishes. Of course in the day-time, when the sun shines, 

 the temperature of such a house will run fifteen or twenty 

 degrees higher ; and ventilation should not be given until 

 the temperature reaches seventy degrees. The great point 

 to be considered in forcing crops of Lettuce or Radishes 

 in greenhouses is, if possible, not to let the night tempera- 

 ture exceed fifty degrees. Of course this cannot be helped 



