VOL. LI.] PHILOSOPHICAL TRANSACTIONS. 333 



On cutting open this outer integuoient, there appeared a pod completely oval, 

 as that of the silk-worm. It was covered with some floss-silk, by which it was 

 connected to the outer coat, being of the same colour. Its length was 2 inches; 

 its diameter nearly one inch; and its weight Q grains. The pod could not be 

 easily unwound, because it was perforated by the moth: but on putting it in hot 

 water, he reeled off so much as sufficed to form a judgment of the strength and 

 staple of its silk. The single thread winded off the pod in the same manner as 

 that of the common silk-worm; seeming in all respects as fine and tough. He 

 doubled this thread so often as to contain 20 in thickness ; and the compound 

 thread was as smooth as elastic, and as glossy as that of the common silk-worm. 

 He tried what weight it would bear; and it bore 15^ oz., and broke with some- 

 what less than l6, on several trials. He then tried a thread of the common silk- 

 worm, which was also composed of 20 (in thickness it rather exceeded the other) ; 

 and it broke always with 1 5 oz. He boiled a part of the cocoon in water for 4 

 hours, that he might know whether it was composed of a gum in any sort muci- 

 laginous; and he found that it was as indissoluble as that of the common silk- 

 worm. The common silk-pod, with all its floss, weighs usually but 3 grains: 

 and here is a pod which weighs 7 times as much. If the outer coat, which 

 weighed 12 grains, were all to be used only as floss-silk, there remain Q grains 

 capable of being reeled; which is above 3 times as much as can be reeled from 

 the common cocoon. But he is of opinion, that when the pod is fresh, and not 

 hardened by age, the whole outer coat may be reeled off": for the pod on which 

 he made these trials was 7 or 8 years old. 



On inquiry, he found that the moth of this pod is called the isinglass by Ma- 

 rian. It is a very large moth, being 5 inches from the tip of each wing ex- 

 tended. It differs from the silk moth in having a proboscis, which intimates 

 that it feeds in its papilio state, whereas the silk-moth never eats. The cater- 

 pillar which produces this pod is a native of America. It was found in Pennsyl- 

 vania : the pod was fixed to the small branch of a tree, which seemed to be 

 either of the crab or hawthorn species. The leaf of the tree had also helped to 

 support the pod ; for the mark of its ribs was apparent on the surface of the pod. 



XJ. A Thermometrical Account of the Weather, for One Year, beginning 

 September 1753. Kept in Maryland, by Rich. Brooke, M. D. Communi- 

 cated by Mr. Henry Baker, F. R. S. p. 58. 

 Merely a journal of the thermometer, with the weather, as to winds, rains, 



snow, &c. 



XII. A Thermometrical Account of the Weather, for Three Years, beginning 

 September 1754, as observed in Maryland:/. By Rich. Brooke, M. D. p. 70. 



This is of the same nature as the preceding article. 



