153 



practice to mix together in the heap the horse and cow duns:. Horse manure fer- 

 ments and heats more readily and rapidly than cow dung. The mixing of the two 

 prevents the former from becoming fire-fanged, which means, to a large extent, 

 depreciation in value, and at the same time a fermentation is set up in the colder 

 cow dung which renders its fertilizing constituents more available for plants. 



" With regard to your question respecting the frequent fires ' commonly credited 

 to unknown causes,' it is quite possible that many of these are true cases of spon- 

 taneous combustion ; yet, undoubtedly some are occasioned by the smouldering 

 embers from the pipe of the farmer, his hired man, or the tramp, or are due to the 

 carelessness in the use of unprotected lights, or caused by the viciousness of incen- 

 diaries. Without data, it is impossible to state what percentage of fires is due t,«> 

 these respective causes." 



