GREENHOUSE ARCHITECTURE 59 



plants to cold drafts, (3) they are lighter, (4) 

 they are more easily cared for, (5) the light is 

 more equally distributed over the whole 

 house, (6) they quickly clear themselves of 

 snow, (7) they contain a larger volume of 

 air, and (8) they require fewer ventilators 

 and less ventilating machinery. 



On the other hand the following disadvant- 

 ages are pointed out: (i) Their great height 

 makes them a target for storms which in 

 winter cause a greater radiation of heat, (2) 

 they are less easily re-painted and re-glazed, 

 and (3) the first cost is greater. 



Notwithstanding these objections, how- 

 ever, the single house of moderate size (40 to 

 60 feet in width) seems destined to become 

 more and more popular. 



Curved-roof Houses. Curved or curvilin- 

 ear roofs are now seldom seen, except on 

 conservatories and show houses. Their chief 

 use is for ornamental effect. They originated 

 in an attempt to so arrange the glass as to 

 more perfectly intercept the direct rays of 

 the sun, but in practice they have proved lit- 

 tle, if any, superior to the straight roof, and 

 the expense is considerably greater. They 

 have never come into general use in a com- 



