ing their source, as assumed, in the force of repulsion generated by the latter action. The force of these currents or winds, as connected with the concentric action which induces them, being esteemed to express the sum or measure. The same opposition of forces, attractive and repulsive, being equally generated in the meteors of the superior region of the atmosphere; notwithstanding that, as contrasted with the former, they develope themselves differently for as it is in the principle of convergence to a centre or axis that these the meteors of the middle and superior region of the atmosphere have their source, it follows, according to this law of electric and magnetic action, that such convergence or principle of attraction in these meteors, gives birth to, and originates at the same time, an opposite or repulsive action from them to the same amount;-these opposite actions expressing mutually, each the sum of the other.-This brings us to the principle in which the winds or currents connected with the latter class of meteors have their source ;-they being, as assumed, contingent on the repulsive force originated by the opposite or concentric action in which, as stated, these meteors have their source. And, as being the counterparts of such concentric action, they are proportionally strong or more violent, as the latter action which originates them is more powerful; and vice versa :-their relations in this respect being esteemed invariable. And as,

when such meteors form on an electrical ground, as in summer, and in the lower latitudes, (i. e. when the electric action of the sun in the inferior region of the atmosphere, as contrasted with its opposite, is the dominant action,)-from the action in which they have their source being, in general, more concentric than when under opposite circumstances, as in winter and in the higher latitudes, they form on a magnetic;-the first effect of the repulsive force thus created is, usually, to originate the explosive phenomenon of thunder. And of this force, the lightning and thunderbolt may be considered to express the sum, equally as that of the concentric action in the meteor which originates it; and of which storm and hurricane are but different modes of development. These latter, as in winter and in the higher latitudes,-owing to the action in the meteor which induces them being less concentric than in the thunder-cloud, or when it forms on an electrical ground, being the usual manner in which this the repulsive force it engenders develops itself. And which difference in the manner of development of the repulsive force in these meteors, may probably be further owing to the acting and exciting principle in the former case, or thunder-cloud, being the inflammable base of the superior region-more particularly connected with magnetic action-hydrogen: as in the latter its opposite-oxygen. The principle, however, being the same in both; as with

out the action of convergence in the meteor, to which they are referable, in the first instance, they could not in either case occur :-contingent, as these opposite actions are assumed to be, on the fundamental law of nature so frequently noticed-the union of opposite progressions of the same kind.

CHAP. XVI.

Connexion observable between certain Classes of Localities and of Meteors with each other, equally as with the Changes respectively in each of the Meteoric Circles-Annual, Lunar, and Diurnal.-The Aurora Borealis.

BUT, as the opposite actions of the sun on the atmosphere revolve in three circles-the diurnal, the lunar, and annual; and of which, as constituting the ground of meteoric action in the former, it is the action in the latter or annual circle which chiefly determines the effects on the weather induced by the actions in the lunar and diurnal. And that, as noticed in a preceding paragraph,—a fixed and determinate relation always exists between the relative amount of these the opposite actions of the sun in the annual circle and the position of the earth in the ecliptic. Both actions of the sun, as, from after the periods of the equinoxes they converge to their res

pective main foci in the opposite or summer and winter hemispheres, necessarily increase progressively, as the earth approaches its apsides at the solstices; when, or rather some time after, from these being the periods of their greatest concentration, these actions as connected with the annual circle, attain their maximum degrees of force on the temperature. To this circumstance, I say, and to the difference which occurs in the relative force of either action of the sun, whether in the summer or winter hemisphere, as it diverges from the site occupied by its main focus, whether at the pole of the latter, or tropic of the former,—it is owing, that in both hemispheres during these the opposite solstial seasons of summer and winter, there are certain lo- * calities which, from the weather not being disturbed but by the great changes which take place in the annual circle, connected with those of the seasons, may be said more particularly to belong to the latter, or annual circle, viz. those which lie in the vicinity of the main foci of these the opposite actions of the sun. And that, in proportion as we recede to a greater distance from these main foci, whether in descending from the pole of the winter hemisphere, or in ascending from the tropic of the opposite, that the relative force of the existing dominant action of the sun on the atmosphere diminishes, so as that the changes in the lunar circle are sufficiently powerful to induce changes in the wea

ther, that thence there is another class of localities in both hemispheres during these seasons, bordering on the former, which is more particularly connected with the lunar circle. And finally, that as in the mountainous districts of these the temperate zones of both hemispheres, and in the vicinity of the sea, where, from the near approach to an equilibrium which, even in winter and summer, exists between the opposite actions of the sun, that the changes in these actions which take place in the diurnal circle of their movement, are at times sufficient to induce changes in the weather. This causes that, similar to the annual and lunar, there is a third class of localities in both hemispheres, which, during summer and winter, may be said more particularly to belong to the diurnal circle, as connected with the ordinary changes of the weather. For, as regards those of a different class, or such as have their source in the changes which take place in the annual circle: as the actions in the lunar and diurnal circles are united with those in the former; the periods of their occurrence usually correspond with those when, according to the order of their occurrence in the latter, they should occur;-as being the expression of the conjoint action of all three at the time.

It is further to be observed as not a little curious, that similar to the connexion observed to exist between certain classes of localities and each of the