PITS HEATED BY HOT WATER, &o. 



447 



The water re-enters the boiler from the 

 tank by descending through a pipe, the 

 orifice of which is level with the floor of 

 the tank at k. 



Dalkeith bulb-pit, figs. 623 and 624, is 

 in size and arrangement similar to the last, 



Fig. 623. 



only, instead of a bed of sand, the pots 

 stand on the slates which cover the tanks. 

 a shows the stair leading down to the 

 passage from the back, b the chimney, 

 c stoke-hole, d pipe for supplying the 

 boiler and pipes with fresh water, e the 

 gauge-pipe, the external orifice of which 

 is level with the full height of the water 

 within, so that, when the water flows 

 from it in charging, it is certain that 

 boiler, pipes, and tanks are full. This 

 pipe is left open, so that, should the water 

 expand from being over-heated or too full, 

 it finds a ready escape. Fig. 624 is a 



Fig. 624. 



section across the furnace a and boiler b, 

 showing also the flow and return pipes 

 c d in front, and also the supply-pipe e. 

 In the first instance, the slate covering 

 extended from the passage across the pit 

 over the tanks and hot-water pipes, and 

 was let 3 inches into the front wall. This 

 was found not to answer the purpose, as 

 the pipes, being covered, gave little heat 



to the atmosphere. We have since had 

 them altered, laying the pipes bare, and 

 the top of the cavity in which they are 

 being left open, which gives us sufficient 

 top heat, and at same time counteracts 

 the effects of too much damp. 



The stoke-hole p is behind, and wholly 

 sunk under the ground-level ; it is cov- 

 ered with a door, and descended to by 

 steps. There is a space also arched over 

 for keeping the supply of coal. The 

 chimney, being carried up 10 feet, is not 

 shown at full height in section, and is 

 finished with a cannon-shaped chimney- 

 pot. 



Dalkeith cucumber-pit is nearly upon the 

 same principle as the propagating-pit. In 

 it we also found that covering the hot- 

 water pipes in front induced an insuffi- 

 ciency of atmospheric heat ; we therefore 

 have removed the pavement on top of 

 the tank, and replaced it with other 

 stones 9 inches narrower, which we find 

 of great advantage. Under the bed of 

 soil is the tank covered with Caithness 

 pavement. Along the back of the bed 

 are placed, 4 feet apart, small tubes, 

 through which water is occasionallypoured 

 to reach the roots, instead of applying it 

 on the surface of the bed. Under the soil 

 is placed, immediately above the pave- 

 ment, a drainage of broken pots 3 inches 

 in depth. The cucumbers are trained 

 under the glass to a trellis of small cord, 

 so that it may be cut to pieces when any 

 of the larger branches of the plants are 

 to be removed. The fruit, when set, are 

 placed in glass tubes, which are suspended 

 from the roof. Under the tanks, which 

 are supported upon flat brick arches, are 

 forced, during winter, sea-kale, rhubarb, 

 &c. These openings are furnished with 

 doors which exclude the light, and the 

 sea-kale is thus blanched without trouble. 



Dalkeith nursing pine-pit. — This pit is 

 heated by hot water in the usual manner, 

 with a bed of leaves, into which the plants 

 are plunged. It forms a continuation of 

 the cucumber pit last described. We 

 may here observe that the four pits last 

 noticed are 6 feet wide in the clear — a 

 width we would not have adopted, had it 

 not been that the sashes were at first 

 made for another purpose ; and had it 

 not been for local circumstances, we would 

 have ranged them from north to south, 

 instead of from east to west, and made 



