1820.] Abraham Gotleb Werner. 247 



and a short Attempt to determine the precise Species of Moun- 

 tains to which it may in future be appUed. 



In Hoepfner's Helvetic Magazine of Natural History, he pub- 

 lished An Attempt to explain the Origin of Volcanoes from the 

 Inflammation of large Beds of Coal, and the Connexion of this 

 Circumstance with the Formation of Basalt. 



In Von Crell's Chemical Annals, On the Buzzen-Wacken of 

 Joachimstal. 1789. Band 1, 8, 131. 



In the Magazine of Medicine and Natural History, A Descrip- 

 tion of a new Ore of Silver (Arsenical Silver). A Letter from 

 Leslie relative to a singular Specimen of Crystallized Gypsura 

 found in an old Fortification. 



Article II. 



Ohaervations on the Barometer, Thermometer, and Rain, at 

 Manchester, from 1794 to 1818 inclusive.* By John Dalton. 



I. Of the Barometer. 



In a long series of observations it is scarcely to be expected 

 that the same instruments can be used throuohout. Accidents 

 are occurring which either derange or destroy them. It is 

 expedient, therefore, to notice such occurrences ; as it seldom 

 happens that instruments, particularly barometers, are replaced 

 or renovated in like circumstances as before ; and if this is not 

 the case, they must necessarily mislead in comparison. 



During the first period of five years, I had a barometer con- 

 sisting of a straight tube of the usual length, and betw^een one and 

 two-tenths of an mch internal diameter ; it was carefully filled 

 •with dry mercury, and inverted into a cyhndrical cup containing 

 mercury ; the diameter of the cup w^as such as to require 

 scarcely any sensible allowance for the rise and fall of the mer- 

 cury in the tube. It suffered no material change, as may be 

 inferred indeed from the annual means, till • ^ar the end of the 

 period. During my absence in August. /98, it had been 

 in unskilful hands ; a part of the mercu iiad been lost out of 

 the cup, and probably a few atoms of air Jiad got into the tube. 

 Not being at that time particularly interested in meteorology, I 

 contented myself with noting the daily observations as usual, 

 without summing up the monthly means, or making any compa- 

 rative observations. The consequence was, that some years 

 elapsed before I was struck witli the depression that had taken 

 place in the mercury, which, upon examination, appears to have 



• Read before the Literary Society at Manchester, Nov. 13 and Dec, 11, 1818. 



