FITZ-ROY WEATHER FORECASTS. 
269 
of the instrumental indicators, is brief in duration, while that of 
a gradual change is more lasting. 
12. Eapid changes of all kinds commonly presage violent 
atmospheric commotion. 
13. The wind usually blows from a region where the barometer 
is high to one where it is low. 
14. The force of the wind is usually proportionate to the 
differences of barometric pressure at adjacent places. In other 
words the greater the barometric tension the stronger the wind. 
15. Strong winds are far more steady in direction than light 
or moderate winds. 
16. Great storms are usually shown by a fall in the barometer 
exceeding 1 inch in 24 hours, or by a fall of nearly of an 
inch in one hour. 
17. The barometer frequently continues high during a JST.E. 
storm, but there is a fall of the thermometer. 
18. Gradual changes of weather are shown by a gradual rise 
or fall of the barometer ; for instance by a rate of of an 
inch in one hour. 
19. Great differences of temperature at the same or adjacent 
places are followed by changes of weather. 
20. It is concluded from the foregoing remarks that a know- 
ledge of the differences in the barometer and thermometer at 
different times in the same place are no less important than a 
knowledge of those simultaneously observed at different places. 
21. Sea disturbance often precedes gales. 
22. Great storms are frequently preceded by excessive 
meteorological disturbance or by heavy falls of rain or snow, by 
much lightning, by unusual cold, or by excessive heat. 
23. Calms may be due to either of three different states of 
weather : — (u) The appulse of winds coming together from 
opposite quarters. (6) The divergence of winds going towards 
opposite quarters, (c) The centre of cyclonic storms. The 
barometer rises in (a) sinks in (6) and is extremely low in (c). 
24. Beyond a doubt electricity plays an important part in 
the state of the weather, but at present we possess no means of 
stating any defined conclusions. 
The forecast for each of the districts into which the United 
Kingdom was divided, was obtained by summarising the actual 
weather prevailing in the several districts and by applying to 
this summary the foregoing maxim. The separate forecasts 
were then collated and revised, regard being had to (1) the 
mutual actions of the estimated weather in each of the other 
districts. (2) To scattered information in respect to such 
distant areas of high and low barometer, as the limited number 
of continental stations afford; and (3) to geographical conditions 
of mountain, plain, or sea by which the free movements of the 
