BOTTOM HEAT. ^ 7 



As a rule, it is much the safest plan to employ a 

 respectable hot -water engineer to erect the heating 

 apparatus, subject to specifications drawn by some one 

 practically acquainted with the degree of temperature 

 required, and the extent of pipe necessary to that end, 

 the contractor to be bound to keep the whole in work- 

 ing order for one year after erection ; and if at this 

 date the boiler is sound, and the joints and valves all 

 right, the inference is that they will continue so for 

 many years. ^ 



The pipes should be painted a dull black colour, as 

 being that most suitable for radiating heat. 



BOTTOM HEAT. 



Gardeners have for many years felt that it was ex- 

 ceedingly unnatural to place the branches of the vine 

 in a high temperature, while the roots were in the cold 

 soil of the border outside the house, and they have had 

 recourse to various expedients to remedy this clearly 

 recognised evil. Hot fermenting dung has been applied 

 to the surface of the border, which did some good, 

 more by its negative than its positive action, in so far 

 as, if the heat from it did not penetrate the border to 

 any depth, it at least, if applied in autumn, prevented 

 the escape of the heat the border had derived from the 

 sun during the summer. Wooden shutters, and in 

 some instances glass, have been laid on the surface of 

 the border to prevent the radiation of its natural heat. 

 All these methods were well known to be very defec- 

 tive ; and it is only of late years that the heating of 

 vine-borders from beneath by means of hot- water pipes, 

 as shown in fig. 1, has placed the temperature of the 

 roots as completely under the gardener's control as that 



