[ * 7 * ] 
monthly Differences are alfo very variable, fo that 
their Agreement at any time feems to be but acci- 
dental. 
Secondly , I obfcfve, that the Defcents of the Mer- 
cury below the mean Heights of each Place, taken 
in this way of Dr. Jurins , are generally much greater 
than the Afcents of it above 5 and there are alfo other 
extraordinary Defcents of the Mercury in every Year, 
of the fame kind. The Rcafon I take to be, becaufc 
the Expanfion of the Air, whereby it becomes lighter 
in fome one Place, being the Original of the Altera- 
tions in the Atmofphere, its Effefts by Condensa- 
tion or Accumulation of the Air in the Places round 
about will be more difperfed, and therefore lefs fen- 
fiblc. 
Thirdly , The Variation or Range is greater the 
farther North, as has been heretofore obferved, and 
appears in thefe Tables, in which I have put the Lati- 
tude of each Place 5 and likewife’tiS' greater generally 
in the Winter than Summer Months. The Sum ot 
the Motion of the Mercury upwards and downwards, 
taken from the Berlin wandring Line, with a Pair of 
Compafles, in the Year 1726, amounts to about 76 
Inches, which gives 5 for a’ Month, and about 0,21 
for each Day. But the Barometer is by much mod 
Ready in the Summer. 
Fourthly i The mean Height of the Barometer hath 
already been apply'd to determine the refpeftive Heights 
of Places, and alfo the abfolute Height above the Surface 
of the Sea. Dr. Scheuchz,er y in his Tables publifh'd 
in the TranfaBions of this Society, N° 40 y, 40 6. 
fuppofes, from Mr. Marriott the mean Height at the 
Surface of the Sea to be 2 8" i ! " Baris Meafure, which 
' ' * reduced 
