94 Proceedings of Royal Society of Edinburgh [sess. 
be observed that the means for August and September differ con- 
siderably from each other. The results point to two marked 
peculiarities in the differences of the reduced barometers in wet, 
cyclonic weather, as shown by the August curve ; and in dry, anti- 
cyclonic weather, as in the September curve. During the times 
of abnormally high temperature and great dryness, which are so 
characteristic of anti-cyclonic weather, the reduced barometer at 
the top reads higher than at Fort- William; and, on the other hand, 
during advancing cyclones, when the atmosphere is highly charged 
with vapour, the reduced barometer at the top reads lower. 
Table II. — Showing the Mean Diurnal Variation of the Differences 
between the Reduced Barometers of the two Observatories for 
the Six Months ending January 1891. The minus sign indi- 
cates that the mean of the reduced High Level Barometer was 
the lower of the two ; no sign that it was the higher. 
Aug . 
Sept . 
Oct . 
Nov . 
Dec . 
Jan . 
6 
Months 
inch . 
inch . 
inch . 
inch . 
inch . 
inch . 
inch . 
1 A.M. 
•010 
•016 
•002 
•ooo 
•002 
-•005 
•004 
2 „ 
•007 
•017 
•ooo 
-•002 
•005 
-•005 
•004 
3 „ 
•007 
•018 
•001 
•ooo 
•004 
- -006 
•004 
4 „ 
•007 
•016 
-•001 
•003 
•001 
-•007 
•003 
5 ,, 
•006 
•012 
•002 
•001 
•ooo 
-•001 
•003 
6 „ 
•002 
•012 
•002 
-•002 
-•001 
•ooo 
•002 
7 „ 
•001 
•012 
•003 
•002 
•001 
•001 
•003 
8 „ 
-•006 
•007 
-•001 
•002 
-•001 
•003 
•001 
9 „ 
-•008 
•003 
-•002 
•001 
•003 
•004 
•ooo 
10 „ 
-•011 
•001 
-•005 
-•002 
•002 
-•002 
- -003 
11 „ 
-•010 
•001 
-•006 
- -004 
- -002 
- -001 
- 004 
Noon . 
- -012 
•003 
-•007 
-•005 
-•006 
-•001 
-•005 
1 P.M. 
-•009 
•007 
-•007 
-•009 
-•006 
-•001 
-•004 
2 „ 
-•009 
•001 
-•007 
-•007 
-•006 
- *006 
- -006 
3 „ 
-•009 
•001 
-•007 
-•006 
-•005 
-•004 
-•005 
4 „ 
-•007 
■002 
- -009 
-•007 
-•004 
-•002 
-•004 
5 „ 
-•005 
•007 
-•002 
-•007 
-•003 
•006 
-•001 
.6 „ 
-•004 
•007 
-•003 
-•009 
-•001 
•004 
-•001 
7 „ 
•002 
•015 
•002 
-•005 
•ooo 
•004 
•003 
8 „ 
•003 
•015 
-•002 
-•006 
•002 
-•004 
•001 
9 „ 
•007 
•021 
•002 
- -004 
•004 
- -002 
•005 
10 „ 
•007 
•017 
•003 
-•003 
•001 
-•004 
•004 
11 „ 
•009 
•020 
•002 
•003 
•003 
-•003 
•006 
Midnight 
■008 
•018 
•000 
•001 
-•001 
- -005 
•004 
