i8 THE BOOK OF THE PEACH. 



plate resting on a nine-inch wall, rising one foot 

 above the floor-line of the house. This will give a 

 clear space of nearly ten feet between pathway and 

 the bottom of the ridge, and an angle of about 

 thirty degrees to the sun. Span-houses should, 

 as a matter of course, be provided with two sets of 

 roof ventilators, these being hung from the ridge, on 

 either side, at intervals of four bays, and the venti- 

 lators on one side should be fixed angle-wise to those 

 on the other side, water-tight hinges being used for 

 the purpose. The ventilators, as in the case of 

 " lean-to's " and "three-quarter spans," should be 

 regulated by Wolland's continuous opening gear, the 

 front vents being also opened by machinery. 



ON HEATING PEACH-HOUSES. 



Where any extent of four-inch pipes say from 

 five hundred feet upwards is to be heated, the 

 horizontal tubular boiler is to be recommended, 

 sizes being supplied by the makers of this descrip- 

 tion of boiler to meet special requirements in the 

 matter of heating, as under : 



No. i size, with nine 5-in. pipes on top and three 3-in. pipes at 

 sides. 



Length of Boiler- H ^'S ? ' 



4 ft. 6 in. ... 750 ft. 



