SILK WORMS. 93 



NONG-SANG-THSIOUEN-CHOU. \ 



When the silk worms are about hatching, they require 

 an extreme heat; at that time the air Is still cold. After 

 the third sleep (or the third moulting,) the silk worms re- 

 quire coolness. At that period the air is warm. Besides 

 the wind, rain, dull, and clear weather often comes on un- 

 expectedly ; the temperature of the morning and evening, 

 that of the day and night, undergoes great changes. If 

 under these circumstances, the proper measures are not 

 taken, the silk worms soon become sick. But all these 

 changes of the atmosphere may be guarded against, if the 

 rules we have described, above be faithfully followed. 



All around the nursery, (that is to say, at each window,) 

 window blinds must be placed, which can be rolled up and 

 unrolled at will. In the middle of the room, a fire must be 

 lighted under ground. If the silk worms require heat, and 

 the external air be cold, the mats that cover the windows 

 must be let down, and the heat disseminated throughout 

 the nursery. Then the cold from without cannot penetrate 

 there, and a mild temperature is enjoyed throughout. But 

 if it be rigorously cold, it will be impossible to warm the 

 apartment, even by opening the doors of the oven ; clods of 

 dry dung must be lighted on the outside, and when they 

 are set on fire, and produce no smoke, they must be placed 

 at the four angles of the silk room. Soon a mild heat will 

 be spread throughout ; and as soon as the cold is dimin- 

 ished the rest of the burning lumps must be carried away. 



When the silk worms require cooling, and the exterior 

 air is warm, the openings of the heated pipe must be shut, 

 and the window blinds raised up; then the interior heat 

 moderates, and the fresh air from without penetrates the 



