1837.] 



Meteorological Observations. 



209 



Two or even three strata of clouds are very common in this district of 

 South Africa. The lowest frequently resting immediately on the land 

 and sea. The height and .^hickness of these strata, their connexion 

 with cross or opposite currents of wind in the regions where they subsist, 

 and the laws of their formation in gradual intermixture, deserve to be 

 studied with care, and with reference to the hygrometic state of the air 

 at the time and place, and for several hours before and after. 



Of Thunder and Lightning, and of the Electrical state of the Air. — 

 Connected with this part of the subject is the observation of shooting 

 Stars and luminous Meteors. Remarkable ones should be noticed, and 

 the moment of their appearance, their direction, duration, length of 

 path, and course among the Stars, ascertained and noted, with the phe- 

 nomena of their increase and decay of light, apparent size, separation 

 into parts, trains left behind, &c. The general direction (if any) which 

 they observe on particular nights, is a point also to be attended to. 

 Such are the frequency and brilliancy of these splendid phenomena in 

 the clear sky of this colony, that there can be no doubt of their afford- 

 ing an available method of ascertaining the differences of longitude of 

 the most distant stations, if duly observed by persons furnished with 

 means of ascertaining the time. 



Thunder-storms of course will be noticed when they occur under the 

 general head of the weather, but it is of consequence also to notice dis- 

 tant lightning, not accompanied with thunder audible at the place of 

 observation (by reason, of its great distance),* especially if it takes 

 place many »days in succession, and to note the quarter of the horizon 

 where it appears, and the extent it embraces. In an actual thunder, 

 storm, especial notice should be taken of the quantity of rain that falls, 

 and of the fits or intermittances of its fall, as corresponding, or not, to 

 great bursts of lightning, as- also of the direction of the wind and the 

 apparent progress of the storm with or against it* 



Observations of the Electrical state of the Air in serene weather are 

 unfortunalely too much neglected. The apparatus they require is 

 simple, and by no means costly, and may be constructed indeed by any 

 one for himself with ease. 



If the Committee in this their first Report do not dilate on this and 

 other of the less usually practised observations of Meteorology, it is 

 because they wish for the present chiefly to call attention to the accu- 

 mulation of regular and daily observations of a more definite and 

 numerical character. With this view they have drawn up, and by the 

 liberal aid of Government, have procured to be printed skeleton forms, 

 for immediate distribution among such Correspondents of the Insti- 

 tution, and others, as may be willing to undertake their filling up. 

 These comprise, it is true, only the registers of the Barometer and its 



* Thunder can scarcely ever be heard more than 20 or 30 miles from the flash which 

 produces it. Lightning, on the other hand, may he seen (or at least its reflexion on the 

 *lo! rtsj forming what is called sheet lightning) at the distance of 150 or 200 miles, 



