Meteorological Ohservaiions. 265 



Art. YII. — Abstracts of Meteorological Observations made at St. 

 Johns, Neivfoundland, and at Canton, in China : with so'me 

 Notice of the Half Yearly Inequalities of Atmospheric Distri- 

 bution, which appear in these Observations ; by W. C. Red- 

 field. 



The annexed summary of meteorological observations at St. 

 Johns, was kindly furnished by Joseph Templeman, Esq., having 

 been printed by him for circulation. The summary for ten years 

 at Canton, in China, was obligingly forwarded by John Slade, 

 Esq., and has appeared in the Canton Register. A comparative 

 half yearly analysis of these observations, and of those made by 

 me at New York, is herewith submitted. 



Observations at Newfoundland. 



The observations at St. Johns include a period of five years, 

 ending with 1838. The barometer, we are informed, is 140 feet 

 above the sea level. The annual mean of the barometer, dedu- 

 ced from these observations, is 29.735 inches ; while the mean 

 of my own observations near the sea level at New York, for the 

 same period, is 30.111 inches :*" — showing a difference in the 

 mean atmospheric pressure of 0.376 inch ; or more than one third 

 of an inch of the barometric column.f Part of this difference, 

 equal to about 0.180, is due to the difference of elevation of the 

 two instruments ; which when added, gives 29.915 inches for the 

 sea level at St. Johns. If we assume the annual mean at the 

 two places to be equal, there still remains a discrepancy of 0.196, 

 or 1 inch, nearly, to be accounted for. In the absence of more 

 definite information concerning Mr. Templeman's barometer, I 

 am inclined to ascribe this discrepancy to the stretching of the 

 leather which forms the bottom of the cistern, while in a moist 



* At a mean temperature of the mercury of about 68° or 70° F. 



t I had recently an opportunity to compare the adjustment of my glass-cisterned 

 barometer with the standard of the Royal Society, as transmitted by means of one 

 of Newman's best iron-cisterned barometers, in the care of Lieut. Riddell, R. A., 

 who has charge of the Magnetic Observatory which is now established in Canada. 

 The height of the mercury by the scale of my instrument was found to exceed 

 that of the standard barometer by a mean of 0.015 inch : which falls a little short 

 of the permanent allowance I had made for the capillarity of the tube ; the diam- 

 eter of which is four fifteenths of an inch. 



Vol. XXXVIII, No. 2.— Jan.-March, 1840. 34 



