172 IMPROVEMENTS IN THE CUJLTURE OP 



The dung is managed as in West's pit (Jig. 22. 



but with the addition of being watered after it is 

 thrown in, which is found to promote fermentation, 

 and the intensity of the heat. 



One of the earliest instances of steam being used 

 as a bottom-heat with which we are acquainted, 

 was that by Mr. Butler, gardener to the Earl of 

 Derby, at Knowlesly, near Liverpool, in or about 

 1792. It had been used twenty years before, but 

 chiefly for other purposes. Speechly, in 1796, 

 knew only two instances in which steam was applied 

 as bottom-heat; and, with M'Phail, does not think 

 it will finally answer as a substitute for tan. 

 Instances in which it is adopted, are now much 

 more numerous ; but time sufficient has not elapsed, 



