1818.] the Imperfection of the Barometer. 203 



JANUARY, 1811. 9 A.M. 

 Days. R. S. Mr. Banks. Diff. of R. S. 



1 30-26 30-26 -00 



2 30-03 30-04 —01 



5 29-84 29-87 --03 



7 29-86 29-88 —02 



8 29-81 29-84 --03 



9 29-81 29-81 -00 



10 29-92 29-93 —01 



12 •• 29-61 29-66 --05 



14 29-58 29-63 --05 



15 29-58 29-62 --04 



16 29-85 29-86 —01 



17 29-74 29-77 —03 



18 29-73 29-77 --04 



19 30-31 30-32 --01 



20 30-38 30-40 --02 



21 30-04 30-05 --01 



22 30-29 30-21 +'08 



23 30-23 30-23 -00 



24 30-42 30-42 -00 



25 30-51 30-50 +-01 



26 30-23 30-26 --03 



28 29-61 29-61 -00 



29 29-62 29-60 +-02 



30 29-75 29-73 +-02 



31 29-14 29-16 --02 



Here the same general conclusion may be drawn as in the 

 former instances ; the absolute heights of the barometers are 

 generally different, and the proportion between them is not 

 uniform. Mr. Banks's barometer is generally the higher of the 

 two ; but they occasionally coincide, and sometimes it stands 

 lower than that at Somerset-house. The following is the result 

 of 25 observations : 



25 



A very accurate meteorological diary is kept in the library of 

 Sir Joseph Banks, which I obtained permission to examine, 



