1 



this can only be settled by carefully made and accurately recorded 

 tests which we hope another year to make. 



We would suggest that if those who have kept accurate records of 

 tlie temperature of their greenhouses, together with the amount of 

 coal consumed, will send us the figures, giving size of house and kind 

 of heating apparatus, we shall be glad to put them on record in our 

 bulletins for the benefit of those who are thinking of building new 

 houses or refitting old ones. 



GREENHOUSE WALLS. 



The comparative protective value of different materials for construction. 



To determine the value of greenhouse walls constructed of differ- 

 ent materials as a protection against the weather, four sections, six 

 feet long by four high were constructed in the new greenhouse 

 recently erected. 

 Section 1. Concrete, (Roslindale cement, one part to three parts of 



sand). 

 Section 2. Hollow brick, nine inches thick. 



Section 3. Framed hollow wall covered with lining boards, building 

 paper and sheathing on the outside, and the same with- 

 out the paper on the inside. 

 Section 4. Same as section 3, but the space vs^as filled withdi-y pine 

 shavings. 



In each of these walls was made a space five inches wide and one 

 foot long running to the center, in which were placed thermometers 

 so protected as not to be affected by the inside temperature of the 

 house. Other thermometers were placed on the inside surface of the 

 walls similarly |)rotected from inside temperature. 



The temperature of each kind of wall, both inside and surface, 

 was recorded at 7-30 a. m., 3 p. m. and 9 p. m. 



The results are stated in the following tables, in which will be 

 found the daily average temperature of both the interior and inner 

 face of the walls from Jan. 9 to March 1st. 



The outdoor temperature for the same time, is given in the central 

 column, for comparison. 



