182 EXPERIMENT ON HEATING EARTH 



XX.— ACCOUNT OF AN EXPERIMENT MADE 

 UPON HEATING A BED OF EARTH IN THE 

 OPEN AIR DURING THE SEASON OF 1861. 



By E. Teevor Ciabke, Esq., F.R.H.S. 



The Council have received the following letter from Captain 

 Trevor Clarke, which they think of sufficient horticultural interest 

 to lay hefore the Fellows : 



A rectangular cutting was made into the ground 21 feet long 

 by 9 in breadth, and sufficiently deep to admit of the arrange- 

 ments described below. 



.The sides were lined with brick on bed, end to end, and set in 

 mortar. A single 3-inch pipe was carried round the whole, a 

 few inches from the side-walling, supported, at intervals, on single 

 bricks and connected with a Burbidge & Healy's boiler (smallest 

 size). Across the bottom of the excavation were carried, trans- 

 versely, low walls or supports of brick on edge, without mortar, 

 each brick laid at an inch or two's distance from the other, end to 

 end, giving them a sort of pigeon-hole formation, the distance 

 between these walls, or rather rows of bricks, being such that 

 each one formed an abutment for two duchess slates, the ends of 

 which met in the middle of the upper surface of the wall. 



The whole formed a compact slate floor just clearing the hot 

 water piping which was thug enclosed in a shallow chamber 

 below. This flooring proved sufficiently strong to bear the 

 weight of a man walking cautiously over it. The little boiler 

 was surmounted by a rude cistern made of a nine gallon liquor 

 cask. This arrangement gave us some trouble at first from the 

 water continually boiling over. The defect was cured by altering 

 the setting, so that the return pipe should not be exposed to the 

 open fire in the immediate vicinity of the boiler, but I think the 

 cistern would be better placed at the other extremity of the 

 arrangement. The bed was then filled up with fresh strong 

 loam, with a large admixture of old hotbed manure, the slate 

 floor having been first covered with fresh turves as a bottoming. 

 This bed of soil was sufficiently deep to admit of plunging the balls ^ 

 of plants, grown if desired in half-bushel pots. Plenty of fire 

 room was given for the boiler, and arranged so that, in gardener's 



