56 GREENHOUSES 



even span house in this connection are hard- 

 ly worth considering. They are much less 

 commonly built than formerly. Uneven span 

 houses are sometimes constructed with the 

 short span to the south with a pitch of 40 

 degrees or more. This brings the roof more 

 nearly at right angles to the sun's rays, but 

 has little or nothing to recommend it. 



Ridge-and-Furrow Houses. A ridge-and 

 furrow house is in reality simply two or more 

 houses joined together. They may be even 

 span or uneven span so long as the side walls 

 are of equal height. The advantages of this 

 form of construction may be mentioned as 

 follows: (i) They are less expensive to build 

 than separate houses of similar size, on ac- 

 count of the saving in side walls. (2) Not 

 only is there a saving in the number of side 

 walls, but the interior walls may be of cheap 

 construction or may be left out entirely, the 

 weight of the roof being supported by posts 

 alone. (3) Considerable saving is made in la- 

 bor because easy passage may be had between 

 houses. (4) They conserve ground space 

 which is often a considerable item. (5) The 

 houses in the center are protected from wind 

 by those on either side and the radiation is 



