141 



M E T E H L G Y. 



Meteorolo- 

 gy- 



Consisted 

 chieflvof 

 particular 

 maxims 

 regarding 

 changes of 

 the wa- 

 tlier. 



General 

 view of 

 these max- 

 ims. 



Falling 



more civilized predecessors. Few if any of these prog- 

 nostics were the result of philosophical investigation, or 

 profound research. They were of that nature, that phi- 

 losophy could give no rational explanation of them, but 

 as matters of fact they were equally level to the capa- 

 city of the illiterate and the learned ; and in proof of 

 this we need only observe, that many of the maxims 

 which are to be met with in classical authors respecting 

 the changes of the weather, are still found in this as 

 well as other countries, and that too among a class of 

 men, who cannot be supposed to have derived their in- 

 formation from the writings of Greece and Rome. A 

 general view of these commonly received opinions will 

 comprehend all that was valuable in the science, if it 

 may be called so, previous to the general use of meteo- 

 rological instruments, or, in other words, up to about 

 the middle of the last century. 



Our limits will not permit us to enter into a minute 

 detail of the maxims alluded to above, nor are they of 

 so much importance as to require a particular enume- 

 ration. It may be useful, however, to notice some of 

 the most popular, and what have been generally con- 

 sidered the most certain prognostications of approach- 

 ing changes in the state of the weather, as serving at 

 once to illustrate the history of meteorology, and to 

 show what are still the most important desiderata on 

 this branch of physical science. It would be difficult, 

 indeed, if not impossible, to make snch a classification 

 of these prognostics, as to include the various and of- 

 ten fanciful opinions, that have prevailed on this sub- 

 ject. The most commonly received, however, may be 

 arranged under the two following classes : 1st, The ap- 

 pearance of the sky ; and, 2d, Phenomena that take 

 place at or near the surface of the earth. In illustrating 

 these, we shall have an opportunity of noticing certain 

 atmospherical phenomena which cannot well be omit- 

 ted, but which could not with so much propriety be in- 

 troduced in any other part of this article. 



To the first class belong those luminous bodies that 

 occasionally appear in the atmosphere, and which have 

 been denominated meteors, or falling stars. These bo- 

 dies appear to be of different magnitudes, and even of 

 various forms, though this last circumstance may per- 

 haps be the effect of optical deception. In general 

 they seem to be globular, continuing visible only for a 

 few seconds, and moving with great velocity. Their 

 course is on some occasions in a straight line, and on 

 others curvilineal, rendered more distinct by the tail or 

 luminous train which they leave behind them ; and be- 

 fore disappearing they are sometimes separated into se- 

 veral smaller bodies, accompanied with an explosion 

 resembling thunder, more or less loud according to their 

 magnitude or distance. It was long supposed, and has 

 now been proved by the most incontrovertible evi- 

 dence, that these explosions are followed by a shower 

 of solid bodies of a stony or metallic substance, some of 

 which have even appeared luminous in their descent 

 after the explosion, and have been taken up before they 

 had time to cool : (See METEORITE.) This last phe- 

 nomenon, indeed, is of comparatively rare occurrence. 

 Thousands of small meteors, as various in magnitude 

 and brilliancy as the fixed stars, have been seen in all 

 seasons, and in almostevery variety of weather, unaccom- 

 panied either with explosions, or the deposition of solid 

 substances ; nor is it certain that even the larger and 

 more luminous meteors, such as that of 1783, described 

 by Cavallo, or one in 1811, an account of which was 

 given by Professor Pictet in the Bi/iliothcque Brilan- 

 nique for May, 1811, are always followed by a fall of 



meteoric stones. On the other hand, these stones have Mcteorolo. 

 sometimes been observed to fall after a loud detonation, ?y- 

 when no meteor was visible, though this may perhiips *""""" ' 

 be accounted for, from its having been obscured either 

 by the superior light of the sun, or the intervention of 

 clouds. But however this may be, the appearance of 

 large meteors, and the fall of meteoric stones, or, as 

 they have very improperly been called, aerolith.t, are 

 phenomena that appear to be closely connected, and this 

 is almost all that is known upon the subject. We deem 

 it quite unnecessary therefore, to enter into a minute 

 account of the attempts that have been made to classify 

 these luminous bodies, according to their form, colour, 

 or magnitude. Whether they are all of the same origin, 

 but varying in appearance, in consequence eitherof their 

 different distances, or of some peculiar state of the at- 

 mosphere, or whether they are essentially different in 

 their nature, are questions to which, in the present state 

 of meteorological science, no answer can be given. As 

 prognostics of the weather, they have in general been 

 supposed to predict wind, as appears from various pas- 

 sages in ancient authors ; and it is also commonly be- 

 lieved, that the wind which follows will blow from the 

 point of the compass towards which the meteor is ob- 

 served to move. One at least of the various hypothe- 

 ses which have been proposed to account for these phe- 

 nomena is interesting, inasmuch as it appears to explain, 

 in certain cases, the connection between the motion of 

 the meteor and the direction of the wind. 



The hypothesis to which we allude, is that which Hypothesis 

 ascribes meteors to certain vapours arising from the to account 

 earth, and becoming ignited in the higher regions of fc 

 the atmosphere. The origin of this opinion may be P henome - 

 traced to Aristotle ; but from the discoveries in che- 

 mistry, of which that author was in a great measure 

 ignorant, it has assumed, in the hands of the modern 

 philosopher, a more definite form. Halley, and after 

 him De Luc, has endeavoured, on this principle, to 

 account for some at least of the circumstances attend- 

 ing the appearance of luminous meteors. The latter 

 supposes that falling stars proceed from a phosphoric 

 fluid, ascending from some spot of the surface of the 

 earth, which becomes visible only when, by decompo- 

 sition in the higher regions, it takes fire, and light is 

 disengaged. If such a fluid can be supposed to rise 

 in a continued column, without mixing with the at. 

 mosphere, or being dispersed by wind, there is no dif- 

 ficulty in conceiving how it may produce the appear- 

 ance of a falling star. When the upper extremity of 

 the column has reached such a height as to be in a 

 great measure above the region of the clouds and mois- 

 ture, it may, from the drynessof the air, take fire spon- 

 taneously, as phosphorus is known to do when expos- 

 ed to the atmosphere in its ordinary state ; and igni- 

 tion having once commenced, it may be communicated 

 backward to successive portions of the column, till it 

 arrives at a portion of the asmosphere sufficiently moist 

 to extinguish it, or at some point where the column it- 

 self has been broken and separated In these circum- 

 stances, it is obvious that the appearance would be 

 precisely that of a falling star ; and Mr. Forster has 

 ingeniously applied the hypothesis to account for the 

 apparent relation between such phenomena and suc- 

 ceeding gales of wind. It has been long known that 

 different, and even opposite currents of wind, may ex- 

 ist at different heights in the atmosphere at the same 

 time ; and the au'.hor just referred to, has found, from 

 various experiments and observations that when the 

 wind near the surface of the earth ciianges, it frequent- 





