192 



pressed with earth it is at least six inches in thick- 

 ness. Earth to the thickness of six inches should be 

 laid over the straw. The earth keeps the straw dry 

 and prevents the wind from blowing through it. In 

 very exposed situations the pit should be additionally 

 preserved by an outer layer of straw. A thick thatch 

 of straw is very effective, but perhaps a coating of 

 dung is best. Straw, laid loosely on the pit, does little 

 good, as the wind draws through it very easily. It is 

 better when damped and softened, and it is for this 

 reason that freshly-made farmyard manure, or straw 

 which has been trodden in the yards, without having 

 become dung, is so useful. Although the outer layer of 

 straw should be damp, the inner layer should be dry. 

 The temperature within the pit may fall considerably 

 below freezing point without freezing the potatoes, pro- 

 vided the potatoes are not damp on the outside, or in 

 contact with moisture. But if potatoes lie damp, or 

 damp straw lies upon them, they are very quickly frozen. 

 If water drains into a pit the frost will follow it to the 

 middle or bottom of the clamp in severe seasons. It is 

 for this reason that ventilating holes should be closed 

 as soon as fermentation has ceased. It is important 

 that ventilation is provided when the pits are first 

 covered. Small openings should be made on the 

 ridge, and a good handful of the straw covering be 

 partly withdrawn. This will afford an escape for the 

 heated air, but within a few days fermentation will 

 cease, and there will be no good in keeping the holes 

 opened. On the other hand, great injury may be 



