INTER-RELATIONS OF BAROMETRIC PRESSURE. 



511 



31st January 1902, and on Ben Nevis 3T172 inches at 9 p.m. of the same day. 

 During the six hours from 7 p.m. to midnight the mean depression of the wet bulb was 

 4°*9 on Ben Nevis, and at Fort- William 0° - 9, thus showing great dryness at the top and 

 a large humidity at Fort- William. This large humidity at Fort- William was as on the 

 previous days associated with a relatively lower pressure in the lowermost stratum of the 

 atmosphere, resulting in a mean sea-level pressure at Fort-William for these six hours 

 0'046 inch less than at the top of Ben Nevis, or a greater sea-level pressure for the top. 

 In the above cases adduced, high pressures occurred at both Observatories, the sea- 

 level pressure at the top being the larger of the two, and were always associated with 

 small differences between the temperatures at the Observatories, the temperature at 

 the top sometimes exceeding the temperature at Fort- William and a great dryness of 

 the air at the top, but a greatly more humid atmosphere at Fort- William. 



The Cyclonic Type of Weather. — On the other hand, the occasions when sea-level 

 pressure for the top is markedly less than at Fort- William are of very frequent occur- 

 rence, the usual accompaniments being complete or all but complete saturation at the 

 top, while at Fort- William humidity fluctuates about or a little under the average. 

 At the top sunshine is virtually absent and clouds large and continuous ; and the 

 difference between the temperature at Fort- William and the top is very large. The 

 following table shows, for 26th March 1903, the chief hourly observations made on 

 that day. The barometric differences are expressed in thousandths of an inch of 

 pressure. 





Barometer at 32° 

 and Sea Level. 



Temperature. 



Hygrometer 



Depression of 



Wet Bulb. 



Sunshine. 



Rain. 



Wind 

 Scale 0-12. 



Fort- 



Ben 



Differ- 



Fort- 



Ben 



Mean. 



Differ- 



Fort- 



Ben 



Fort- 



Ben 



Fort- 



Ben 



Ben 





William. 



Nevis. 



ence. 



William. 



Nevis. 



ence. 



William. 



Nevis. 



William. 



Nevis. 



William. 



Nevis. 



Nevis. 





Ins. 



Ins. 



Ins. 















Hrs. 



Hrs. 



Ins. 



Ins. 



Dir'n.Force. 



1 A.M. 



28-940 



28 



928 



— 12 



44°-0 



28°"3 



36°-2 



— 1°3'7 



1*6 



•0 







•06 



■03 



S 3 



2 „ 



•954 





940 



— 14 



43 7 



28-5 



36-2 



—15-2 



1-1 



'0 







•03 



•05 



S 2-3 



3 ,, 



•965 





945 



— 20 



43-9 



28-9 



36-4 



—15-0 



1-3 



•o 







•01 



•03 



S 3 



4 » 



•958 





934 



— 24 



46-0 



28-6 



37 3 



-17-4 



3-4 



•o 







•o 



•03 



S 2-3 



5 ,, 



•973 





947 



— 26 



45-6 



28-4 



37-0 



—172 



3-0 



•o 







•01 



•03 



S 2-3 



6 ,, 



•977 





946 



— 31 



44-9 



28-4 



36-7 



—16-5 



2-5 



•o 







•o 



•o 



SSW 2-3 



7 „ 



28-986 



28 



966 



— 20 



46-4 



27-8 



37-1 



—18-6 



4-4 



•0 



•44 



•o 



•o 



■04 



SSW 2-3 



8 ,, 



•990 





976 



— 14 



46-5 



27-8 



37-2 



—187 



4-0 



•o 



•o 



•o 



•o 



•05 



SSW 2-3 



9 „ 



•994 





974 



— 20 



46-5 



28-8 



377 



-17-7 



3-5 



•o 







•o 



•o 







SSW 2-3 



10 ,, 



29-000 





975 



— 25 



47-1 



29-0 



38-1 



—18-1 



3-5 



•o 



•o 



•o 



•o 



■o 



S 2-3 



11 ,» 



28-989 





967 



— 22 



48-6 



29 2 



38-9 



—19-4 



3 '8 



•o 



•o 



•0 



•o 



•07 



S 2-3 



Noon 



•979 





951 



— 28 



46-6 



29-1 



37'9 



—17-5 



2-2 



•o 



■o 



•o 



•02 



•05 



S 2-0 



1 P.M. 



28-991 



28 



944 



- 47 



447 



27-9 



36-3 



—16-8 



2-1 



■o 



■o 



•o 



•06 



■11 



SSE 2 



' 2 ,, 



•957 





916 



- 47 



46-1 



27-9 



37-0 



—18-2 



2-7 



•o 



•15 



•o 



•04 



•o 



SE 3 



3 ,, 



•929 





881 



— 48 



47-4 



29-0 



38-2 



—18-4 



3-3 



•o 



•45 



•o 



•o 



•o 



SE 3-4 



4 ,, 



•925 





894 



— 31 



44-6 



27*9 



36-3 



—167 



2-2 



•o 



•o 



•o 



•04 



•06 



SE 2-3 



5 ,, 



•919 





908 



— 11 



44-6 



27-3 



36-0 



-17-3 



3-0 



•o 



•o 



•0 



•01 



•02 



SSE 2-3 



6 ,, 



•959 





942 



- 17 



42-6 



27-0 



34-8 



—15-6 



1-0 



•o 



•o 



•o 



•05 



•07 



S 1-2 



7 „ 



29-001 



28 



988 



— 13 



41-6 



26-2 



33-9- 



—15-4 



0-7 



•0 







•07 



•03 



S 2 



8 ,, 



•064 



29 



054 



— 10 



41 



26-2 



33-6 



—14-8 



1-2 



•o 







•04 



•12 



SW 1-3 



9 ., 



•091 





077 



— 14 



42-1 



26-6 



34-4 



—15-5 



1-5 



•o 







•02 



•06 



S 1-3 



10 ,, 



•109 





086 



— 23 



41-4 



26-9 



34-3 



—14-7 



1-5 



•o 



• •• 





•06 



•02 



SW 1-3 



11 •> 



•115 





097 



— 18 



42-6 



26-9 



34-8 



-157 



1-0 



•o 







•06 



•o 



SW 1-3 



Midn't 



•118 



29 



089 



— 29 



44-4 



26-4 



35-4 



—18-0 



3-6 



•o 







•o 



•o 



SSW 3-4 



Mean 



28-995 



28 



971 



— 24 



44-7 



27-9 



36-3 



—16-8 



2-4 



■0 



1-04 



•o 



•58 



•87 



2-5 



