206 REMARKS ON METEOROLOGY. 



steadily from one point, or veer about; whether it shift ir- 

 regularly or revolve gradually; and lastly, whether it ap- 

 pear to extend high into the atmosphere, or only affect the 

 lower stratum. 



Barometer. -phe height of the barometer is noticed between 8 and 9 



in the morning, and at the same hour in the evening; but 

 its absolute height is of little consequence, unless we know 

 whether it be rising or falling, when it began to rise or fall, 

 and also what connection there is between these circum- 

 stances and the direction of the wind, and the shape and 

 appearance of the clouds. The following case will illustrate 

 the greater importance of relative than of ahsolvtc observa- 

 tions upon the subject. Suppos*^ that nothing was known 

 of the state of the preceding day, but in the morning we 

 find the barometer at '29"75, its medium height, the wind 

 W, a gentle breeze, and the sky partially clear. These 

 circumstances afford no decisive indication of the probable 

 state of the day, and according to the preceding appear- 

 ances, they may afford either a favourable or an unfavour- 

 able prognostic. If the evening before the wind had been 

 NW, the atmosphere brilliant, and the barometer 29*80, 

 we may expect, that the wind is travelling to the SW, and 

 that rain will probably ensue ; but, on the contrary, if the 

 preceding day had been rainy, the wind in a southerly 

 point, and the barometer low, we may fairly hope that an 

 improvement will tyke place in the weather. It is in my opi- 

 nion principally for want of this plan of retrospective ob- 

 servation, that our meteorological instruments are of so little 

 use. 



Clouds, The occasional remarks form by far the most important 



part of the above table, and upon them I shall now proceed 

 to make some comments. The phenomena of the clouds I 

 consider as forming the most important part of my system 

 of observation, and they require a great variety of terms to 

 designate all their characters. They are varied as to their 

 general shape, size, colour, density, height from the surface 

 6f the Earth, and motion. Beside these there are three 

 points particularly to be attended to, whether their bulk be 

 increasing or diminishing ; whether any change be taking 

 place in their character, and one kind of cloud be gra- 

 dually 



