a4 HISTORT of the SOCIETT, 



night and fix in the morning ; and this it did progreflively, 

 without any intermediate rifing but in one inftance. 



2. Between fix and ten in the morning the barometer con- 

 ftantly rofe ; it alfo did fo progrefif^vely, and rarely with any 

 intermediate faUing. 



3. Between ten in the morning and fix at night the baro- 

 meter fell progreflively, without a fingle exception. 



4. Lastly, between fix and ten at night the barometer rofe 

 progreifively, without any intermediate falHng, except in one in- 

 ftance. 



These are Dr Balfour's general conclufions ; and, accord- 

 ingly, on calling an eye over the table into which he has redu- 

 ced his obfervations, one is immediately ftruck with the ap- 

 pearance of two maxima^ viz. at ten at night and ten in the 

 morning ; and, again, two minima^ alfo diametrically oppofite 

 to one another, at fix in the morning and fix at night. 



The quantity of thefe diurnal variations is not very confider- 

 able, but fufficient, at the fame time, to leave no doubt of their 

 reality. The difference between the contiguous maximum and 

 minimum is fometimes -'o of an inch, though in general it is lefs 

 than half that quantity. 



It does not appear that the above variations have any rela- 

 tion to the heat and cold of the atmofphere, or to the changes 

 of the temperature of the mercury in the barometer, though, 

 with refpe(5l to this laft, we are not furniflied with fuiEcient 

 information. 



Till thefe obfervations are further multiplied and extended, 

 it will be in vain to attempt any explanation of the fads to 

 which they relate. It feems not improbable, however, that they 

 are connected with the reciprocations of the fea and land winds, 

 during the day and night, or with the heating and cooling of 

 the fuperincumbent atmofphere. It would be of great ufe to 



have 



