Proceedings. 39 



circulates round the centre, but it is very light in force, for 

 gradients are easy, that is, pressure is nearly even over a 

 large area; and it cii-culates ^vith the watch-hands because 

 the centre is the highest, and so is on our right hand as we 

 turn our back to the wind ; whereas in the cyclone it was on 

 our left, and it has a tendency to draw away from the centre. 

 Anticyclones often extend over a very large area ; they 

 move very slowly, and so the conditions remain the same for 

 a long period ; and they are accompanied by dull, gloomy, 

 misty weather. We can most of us remember the weather of 

 Christmas, 1883 ; the sun was then obscured by mist for a 

 whole fortnight ; this occurred not only here, but from the 

 Orkneys down to the north coast of Spain, and from Valentia 

 on the west coast of Ireland to Denmark ; and probably a 

 great deal further in all directions. 



The original disturbing action which produces motion in 

 the atmosphere is the heat of the sun, but, as we have seen, 

 the motions of the atmosphere are mainly regulated by the 

 distribution of barometrical pressure over the globe, the par- 

 ticles moving from regions where the pressure is high to those 

 where it is low. 



A few words now as to the use of the barometer as a 

 weather-glass ; on old-fashioned barometers, and on a good 

 many modern ones of an inferior class, will be found certain 

 words, such as "Set Fair," "Fair," "Change," "Eain," &c., 

 and as a consequence people are in the habit of saying when 

 the weather does not accord with that indicated on the scale 

 that the barometer "tells wrongly." Now the barometer 

 only measures the weight of the atmosphere, and it is these 

 words that teU wrongly ; they are misleading, and ought to 

 be entirely ignored. Neither the direction and force of the 

 wind nor the rainfall depend on the actual barometer-reading 

 at the time in any one place, I have known a storm with a 

 S.W. wind that blew down a brick wall in my garden when 

 the barometer stood above 30 in., or "Fair"; it constantly 

 rains heavily with a N.E. wind and a very high barometer. 

 Quite as often we have fine, clear, bright weather and a low 

 barometer. As we have seen, it is the relative height of the 



