268 Correspondence of J. Nicklés. 
tubes. Sir James Hall, in his experiments upon the saw-dust of pine 
wood and of horn in sealed gun-barrels, had observed that the mixture — 
underwent fusion and was cemented into a sort of coal. Similar resulis 
were obtained by Latour with thick glass tubes. ; 
ese are not the only researches which we owe to this lamented ; 
icist; in our previous letter we mentioned that while connected with the — 
Government powder works in 1814, he made some useful improvements 
in that. department, especially in the glazing of powder. 
surprise that it was only in 1851 that he became a mem 
Academy of Sciences. on , 
The aurora borealis and its theory—The late brilliant auroras 
. : ‘ f the 2 
points upon the paper in Morse’s apparatus; the aurora 0 
gust traced continuous lines of greater or less length. These effects lasted 
for several days after the aurora. tl WE 
It is fortunate that the aurora of the 29th was carefully stu studied 
is rver, Who has os 
Coulvier-Gravier declares that he had never seen it more beat : 
the long period of his observations. Del 
The observations during the late auroras support the theory ee a 
Rive, which he has thus defined. The vapors constantly er to the 
* See p. 92, this volume. 
