O F S I L K. 229 



circiimflances mnfl dire6l you. In tem- 

 perate climates they fhould be kept clofe 

 and warm till after their fecond moulting ; 

 in hot climates too much heat and want of 

 air will oftener hurt them than cold. 



It would be of good fervice, where great 

 quantities of worms are kept, to have a 

 thermometer ; and having, by your expe- 

 rience, determined the greateft degree of* 

 cold and the greatefl: degree of heat which 

 •they could bear, without any manifeft 

 figns of harm, you might afterward, as 

 the fpirit in the thermometer varied above 

 or below thefe points, regulate your con- 

 duel. You can give a good guefs at their 

 health by the vigour with which they eatj 

 and their alacrity in coming on the freih 

 leaves which you give them, and hence 

 you might pretty well afcertain the degrees 

 of warmth in which they thrive befl:. A 

 like good ufe might be made of an hygro- 

 meter, which meafures the moifture and 

 drynefs of the air, and moifture hurts them 

 more than cold ; but thefe are niceties 

 which few can or Vi'ill make ufe of. If the 

 worms are near their m.oult, you muft not 

 then judge of their health by their liftlef- 

 nefs and inadlivity, for thefe are at that 

 K time 



