361 
LI. 
ABSTRACT OF METEOROLOGICAL MAL Aka 
MADE AT CAMBRIDGE, NEW ENGLAN 
| BY JOHN FARRAR, 
Hollis Prof. Math. and Nat. Phil. in Harv. Coll. communicated Fan. 1813. 
es Be 
THE following tables exhibit the result of a regular course of ob- 
servations, made by the late President Webber, from January 1790 
to June 1807, and continued from that time to the present by myself. 
The place of observation is elevated about 31 feet above the mean 
level of the seas From 1790 to July 1802 a barometer, furnished by 
the Meteorological Society at Manheim, was used ; from this latter time 
to the beginning of 1810 a barometer made by Champney ; and during 
the years 1811 and 1812, one made by W. & S. Jones, London, provid- 
ed with a floating gage and a scale of correction. The two last in- 
struments are graduated into English inches and hundredths, the first 
into French inches, lines and tenths. The heights are reduced to the 
temperature of 55 of Fahrenheit’s scale, a correction being applied for 
_ the variation above and below this point; and the observations with 
the Manheim barometer have been reduced to English inches and ~ 
hundredths. 
The observations on the temperature from the commencement to 
August 1795 were made with a mercurial thermometer, attached to 
Reaumur’s scale, placed about four feet from the ground, under cov- 
er, but exposed to a free air, and sufficiently protected from any undue 
_ reflection of heat, as well as from the direct rays of the sun. From 
August 1795 to July 1803 Fahrenheit’s thermometer, made by 
Champney, was used, placed abroad in the open air, about 11 feet 
from the ground. From July 1804 to the present time a very good 
thermometer, made by the Messrs. Jones, London. The observa- 
tions with Reaumur’s thermometer are reduced to Fahrenheit’s scale, 
for the pyrpose of a — ready comparison. | 
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