North America hy Dr Holyoke and Professor Dewey. 351 
Cambridge in Massachussets, which is nearly in the same paral- 
lel, thus : 
Mean Temperature of Salem, - 42® 33' - 48®.68 
Mean Temperature of Cambridge, U. S, 42 25 - 50.36 
Difference, 1 ®.68 
As the observations at Cambridge were made only for two years, 
the mean temperature of' the parallel of 40°, which Humboldt 
makes 54°.50, must now be reduced considerably. 
Professor Dewey’s Thermometrical Observations for Five 
Years^ at Williamstoxm^ Massacimssets. 
\ 
These observations were made at 7^ A. M. 2^ P. M. and O’* 
P.M. 
Longitude of Williamston, - 73® W. 
Latitude of ditto, - - - 42° 30' N. 
Height of ditto above the tide-water of the 
Hudson at Troy, - - - 1000 feet. 
1816, 
1817, 
1818, 
1819, 
January, 
21®.03 
20®.81 
20°.26 
28M4 
February, - 
25.15 
15.10 
14.94 
27.73 
March. 
29.35 
28.55 
31.23 
25.86 
April, 
42.68 
43.77 
39.09 
42.19 
May, 
52.81 
54.31 
53.59 
55.30 
June, 
60.64 
59.57 
68.50 
67.22 
July, 
64.64 
67.40 
71.25 
70.31 
August, 
64.89 
66.47 
65.95 
68.99 
September, 
55.02 
58.68 
55.60 
64.01 
October, 
48.42 
45.06 
48.11 
46.31 
November, 
39.73 
38.79 
39.75 
38.21 
December, 
2T.71 
27.02 
22.03 
25.07 
Annual Means, 
44®.35 
43°.79 
44”. 19 
46°.61 
Mean Temperature for Four 
Years, 
. 
44®.73 
Mean Temperature of Three 
Springs for 1816, 
. 
47°.26 
1817, - - 47.11 
1818, - - 47.12 
Mean Temperature of Springs, 47*.21 
Inch. 
Mean of Barometer, 1818, - - - . » 29.14 
•: 1819, ^9.18 
