Prof. Kupffer on the MeanTemperatu--e of Sitlca,in America. 427 



position, and which become so visible in the slight frost of an 

 autumnal morning, partake of the same character. 



Mr. Temple, in his amusing and interesting account of his 

 travels in Peru, and while describing the first indications of 

 the approach to the end of his voyage across the Atlantic, has 

 the following passage, from which it would appear that in- 

 stances similar to that which I have just described, may pro- 

 bably be found in various other parts of the world, and that 

 the power of projecting a web of great length is possessed by 

 more than one of the species. 



" We weighed anchor, and made all sail up the stupend- 

 ous, but wholly uninteresting river Plate, which is 120 miles 

 wide at its mouth, and not less than from 20 to 30, for up- 

 wards of 150 miles inland. In the course of the day, the 

 rigging of the ship, from top to bottom, was literally covered 

 with long Jine cobvochs, that had been blown off the shore, 

 having attached to them their insect manufacturers, who dis- 

 persed themselves in thousands over our deck." — Travels in 

 Peru, vol. i. p. 49. 



I have frequently endeavoured to ascertain to what length 

 one of these spiders had the power of spinning a thread. 

 By letting the insect drop from an object of known dimensions 

 held in the hand, and by winding out the thread, while turn- 

 ing the object, I thought it possible to form some idea of its 

 length. But from the unnatural position of the spicier, and 

 the occasional force necessary to make him work, I have 

 never been able to come to any definite conclusion on this 

 point. But it appears to me probable, that liom 30 to 40 

 yards is as much as can be produced at one time, without a 

 degree of compulsion, or exhaustion, which makes him roll 

 himself up, and become motionless for some time. 



It seems certain that the substance from which the cobweb 

 is composed is a gummy liquid while in the body of the insect, 

 but becomes dry and elastic in the open air, in the same man- 

 ner as threads of any other gummy substance when do drawn 

 out in a half moist state. 



Ramsgate, Oct. 3, 1832. 



LXXIV. Note on the MeanTemperature and BarometricHeight 

 of Sitka, on the North-west Coast ff America. By Professor 

 M. A. Kupffer, of the Imperial Academy of Sciences of St. 

 Petersburgh* . 



THE following meteorological observations have been com- 

 municated to me by M. Lutke. They will afibrd at least 

 on a])proximate idea of the climate of Sitka. 

 • Commiinicafed by the Author. 

 3 I 2 



