VOL. XLVIII.] PHILOSOPHICAL TRANSACTIONS. 425 



set up; which was about the middle of May. And as Fahrenheit's thermometer 

 was but 7 degrees above freezing, it is supposed the winter will not entirely put 

 a stop to observations of this sort. At London, no more than 1 thunder storms 

 have happened during the whole summer: and the apparatus was sometimes sa 

 strongly electrified in one of them, that the bells, which have been frequently 

 rung by the clouds, so loud as to be heard in every room of the house, the 

 doors being open, were silenced by the almost constant stream of dense electrical 

 fire, between each bell and the brass ball, which would not suffer it to strike. 

 Mr. C. concludes this paper with the following queries : 



1 . May not air, suddenly rarefied, give electrical fire to, and air suddenly 

 condensed, receive electrical fire from clouds and vapours passing through it? 



2. Is not the aurora borealis, the flashing of electrical fire from positive, to- 

 wards negative clouds at a great distance, through the upper part of the atmo- 

 sphere, where the resistance is least? 



LIF. Extract of a Letter from Professor Bose. dated Wtttemberg, Aug. J, 

 1753. JVith Observations on it by Mr. Wm. fVaison, F. R. S. p. 358. 



In the beginning of August 1752, after great and continued rains, many of 

 our rivers overflowed the neighbouring grounds, more or less according to their 

 level, to a considerable distance; and the quantity of water was so great, that in 

 some places it was not discharged for more than a week. More particularly the 

 river Unstrut in the territory of the landgrave of Thuringue required a long time 

 to empty itself, not only as that river runs over a large tract of country, but also 

 as between Artern and great Jena, where this river joins the Sales, its bed in 

 several places is very much confined. 



When the inundation was abated, it was observed from the little city Laucha 

 quite up above Artern, not only on the fields and meadows, but also on the 

 bushes and trees, that there was a green and very tough viscous slime, which by 

 the help of a stick could be drawn out to 2 or 3 ells in length. The subsequent 

 heat of the sun dried this matter, and it appeared like wool on the bushes ; but 

 the fields, when seen at a distance, seemed as if covered with sand. This matter 

 had a smooth appearance outwards, but within was like a sheep's skin. Down- 

 wards next tlie ground it had a sort of wool ; and when the whole was washed 

 with soap, it whitened, and appeared like a clean fleece of white wool. Of this 

 substance the country people soon made wicks for their lamps, and several lined 

 their clothes with it, as they would with fur. 



It was further observed, that where this substance was mowed off from the 

 meadows, the grass under it was quickly dried up; but, where it was not 

 removed, the grass in the following December was as green and fresh as in the 

 spring. Thus far Mr. Bose. On which Mr. Watson observes, that the veget- 



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