18 
ON THE DIURNAL VARIATIONS OF WIND ETC. AT BOMBAY. 
Postscript. 
Since the completion of the above discussion, the Quarterly Weather Report of the 
Meteorological Office for the first quarter of 1871, containing the Anemometrical 
Results for Sandwick Manse, Orkney, 1863-68, has been received at Bombay. From 
Table II. page [36] the mean north and east components for each hour of the day in 
the whole period have been extracted. They are as follows : — 
Mean North and East components of the Wind at Sandwick Manse, Orkney, for each hour 
of the day from 1863 to 1868, also their mean diurnal variations for the same period. 
Sandwick Manse 
Hours 
Civil t 
0. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
N. component .... 
-2-65 
-2-67 
-2-55 
-2-49 
-2-34 
-2-28 
-2-20 
-2-29 
Variation 
-0-27 
-0-29 
-017 
-Oil 
+0-04 
+0-10 
+0-18 
+009 
E. component 
-2-90 
-2-85 
-313 
-304 
-2-99 
-314 
-3 09 
-318 
Variation 
+0-27 
+0-32 
+0-04 
+0-13 
+0-18 
+0-03 
+008 
-0-01 
Sandwick Manse 
Hours 
Civil | 
8. 
9. 
10. 
11. 
12. 
13. 
14. 
15. 
N. component .... 
-2-39 
-2-50 
-2-65 
-2-74 
-2-73 
-2-58 
-2-33 
-2 30 
Variation 
-001 
-012 
-0-27 
-0-36 
-0-35 
-0-20 
+0-05 
+008 
E. component 
-2-98 
-2 98 
-310 
-3-49 
-3-70 
-3-69 
-3-92 
-3-68 
Variation 
+0-19 
+0-19 
+0-07 
-0-32 
-0-53 
-0 52 
-0-75 
-0-51 
Sandwick Manse 
Hours 
Civil 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 
X. component 
-211 
— 1 90 
-1-86 
— 1 97 
-2-19 
-2-40 
-2-45 
-2-62 
Variation 
+027 
+0-48 
+0-52 
+ 0-41 
+019 
-002 
-007 
-0-24 
E. component 
-3-51 
-3-34 
-311 
-300 
-2-84 
-2-82 
-2-84 
-2-84 
Variation 
-0-34 
-017 
+006 
+0-17 
+ 0-33 
+035 
+0-33 
+0-33 
The mean components for the whole period are N. — 2‘38 and E. — 3T7. 
The variation of the north components shows a decided double period having maxima 
about 6 and 18 hours and minima about 0 and 12 hours, like the meridional variation 
of the wind at Bombay. The variation of the east components is less regular, but the 
double period, though not strongly marked, is nevertheless unmistakable in this variation 
also. It has a minimum about 14 hours and a maximum about 21 hours, a second 
minimum during the early morning hours and a second maximum between 8 and 9 
hours, showing it to be of like character to the longitudinal variation of the wind at 
Bombay. The combination of these two variations produces a curve (fig. 14) which 
possesses the same general features as the typical curve fig. 9. 
