Hotbed Construction and Management 



1623 



the sand. With square shovels this dry mixture is turned twice. Then 

 water is added, care being taken that none of the water runs off as in 

 doing so it carries away fine particles of cement. As the water is added 

 the mixture is turned again, and when more water is needed it is applied. 

 The turning is continued until the whole mass is thoroughly wet and slightly 

 sloppy. At this stage it is shoveled into the form, and tamped down with 

 a blunt 2x3 -inch scantling in order that all parts of the form may be 

 filled solid. It is quite important, in filling, that the whole form be filled alike 

 on all sides ; then, if it cannot be filled in one day, the top can be moistened 

 with water just before the first batch of concrete is put in the following 

 morning, thus making sure the union between the work of the two days. 



Fig. 17. — Commercial hotbeds. 



A cheaply constructed mat of lath and straw in the 

 middle of the bed 



When the form is completely filled and the concrete is leveled slightlyhigher 

 than the woodwork of the form, short pieces of boards are laid over the top, 

 but not touching the concrete, for protection against rain. In two or three 

 days the form may be carefully removed and the sides of the concrete ex- 

 posed directly to the weather. Care must be taken, however, that the con- 

 crete does not dry out too fast, or it will crack and sometimes heave. A 

 few pails of water thrown on will stop this quick drying; or, on very sunny 

 days, boards or lath screens covering the bed will serve the purpose. 



A 2X4-inch sill set in the cement and fastened by the bolts, lapping at 

 the corners, is then placed on the bed and is to serve as a rest for the sashes. 

 Crosspieces, such as are spoken of for the wooden beds, may be counter- 

 sunk into the sill. The bed is then ready for filling and for the sash. 



