xu 



APPENDIX. 



Thermot)ietrical Table, showing the greatest Difference between the lowest and 

 Temperature in each Month for every Month of the Year for Eight Years. 



highest 



January .... 

 February.... 



March 



April 



May 



June 



July 



August 



September . 

 October .... 

 November . 

 December . 



1816. 



iS-5 



20- 



22- 



23- 



10' 



13- 



27- 



29- 

 28- 



1817. 



32- 



25- 

 2.5- 



21' 



23- 

 14- 



H- 

 13- 

 25- 

 15- 

 30- 

 26- 



18IH. 



27- 



37-5 



31- 



27-5 



27- 



19- 



12' 



11-5 



10- 

 20- 

 27- 



29- 



1819. 



33-5 



37- 



32- 



24- 



17- 



20- 



13-5 



12- 

 ll" 



i8. 

 25- 

 25- 



1820. 



31- 

 43- 

 26- 



22- 



i6- 



24- 

 Il- 

 H' 



21' 

 29- 

 28- 



1821. 



35- 

 38- 

 27-5 



26- 



27- 

 19- 

 15- 

 lo- 

 ll- 



21- 

 27- 



25-5 



1822. 



30-5 

 35-5 

 27' 



24' 



i8-5 



17-5 



19- 



ii- 



11- 



33- 

 285 



25- 



1823. 



27-5 

 29- 



26- 

 26- 

 20- 



15- 



10' 



8-5 

 Il- 

 27- 

 28- 



Mean of 

 8 Years. 



31-1 

 35-1 



27-7 

 23-6 

 21-6 



i8-8 

 14-6 

 11-1 

 13-2 



21- 



27-8 

 26-7 



NOTICE. 



The Barometer used in forming the preceding Barometrical Tables was a marine one, and proved, 

 by comparisons with the barometric observations of that able and accurate surveyor Captain Webb, 

 to be a very good instrument. From April 1816 to June 1821, it was placed in a northern verandah 

 of a low-roomed house, quite out of the influence of radiated heat or partial currents of wind, but 

 exposed to all winds, and hanging about eight feet above the common level of the plain. From the 

 1st of June to the end of November 1823 it hung about 20 feet higher, but in other respects the 

 same as to aspect and exposure to air. The diurnal fluctuations of the mercurial column are now 

 so well known as no longer to excite surprise ; but the occasion of them, when not accounted for 

 by corresponding changes in the atmosphere, has not yet been clearly explained. In a period of 

 several years, I have found the deviation in the rise and fall of the mercury, at stated times in 

 the twenty-four hours, so regular as to be able to reduce it to general rules. Thus I found the 

 mercurial column attained its greatest elevation by about 10 a.m., and remained stationary till 2; 

 its decline then commenced, and continued till 4 p.m. It remained stationary from that hour 

 to 6 P.M. After 6 it again began to rise, and the same course of change as was exhibited by 

 day continued through the night. 



The moment of its beginning to rise and its continuance often varied, however, and so did the 

 fall, but it may be inferred generally that the minimum elevation of the mercurial column is at 

 6 in the morning and 6 in the evening ; and its maximum at noon and midnight. The fall of the 

 mercury each day is generally twice as great as the rise, or nearly so, as will appear from an 

 inspection of the annexed table of the rise and fall for a whole year. 



