MOTH. 23 1 



degree of heat as to kill the inclosed chrysalides; a 

 few only being saved for the breed of the following 

 year. The Moth, when hatched, is a very short- 

 lived animal; breeding soon after its exclusion, 

 and when the females have laid their eggs, they, 

 as well as the males, survive but a very short 

 time. 



The length of the silken fibre or thread drawn 

 by the silkworm in forming his ball, is computed 

 by Mons r . Isnard, a French author, who wrote on 

 the subject of the Silkworm in the seventeenth 

 century, to-be six English miles in length. This 

 computation however appears to be a greatly ex- 

 aggerated one. The length indeed may be sup- 

 posed to differ considerably in different silk-balls, 

 but in general will be found far short of what is 

 stated by Isnard. According to Boyle, as quoted 

 by Derham, a lady, on making the experiment, 

 found the length of a ball to be considerably 

 more than three hundred yards, though the weight 

 was only two grains and a half. The Abbe La 

 Pluche informs us that of two balls one measured 

 nine hundred and twenty-four feet, and the other 

 nine hundred and thirty. It may be proper to 

 add, that the silk throughout its whole length is 

 double, or composed of two conjoined or aggluti- 

 nated filaments*. 



The general history of the manufacture of Silk 



* In the Encyclopaedia Britannica we are informed that the 

 length varies in different coccoons from 200 to 1200 ells, and 

 that in general we may calculate the production of a coccoon 

 from 5OO to 600 ells in length. 



