"In summer, after a long continuance of fair weather, with the barometer high, it generally falls gradually, and for one, two, or more days, before there is much appearance of rain. If the fall be sudden and great for the season, it will probably be followed by thunder." 3d. _It falls frequently and considerably without rain._--This is owing to the fact that _all_ regular, periodic efforts at condensation do not result in rain. The second, third, and fourth classes of storms described, may not (as we have said) _be sufficiently active to precipitate_, although the _series of phenomena_ (including the fall of the barometer) may be, in other respects, perfect. Such an instance may be found in Reid's table, on page 329, and on the 11th of the month. But the fall in such cases is not as great, unless the wind be violent. 4th. _It rises during considerable gales._--But these are of the kind so often alluded to--viz., the N. W., in the northern hemisphere, and the S. W., in the southern; and the _philosophy_ of it has been explained, and is observable. With these explanations, the reader will be able to understand, and practically apply, the barometric changes, in connection with the other phenomena, in forming an opinion of the weather. _The thermometer_ is also an auxiliary. It _rises_, during the winter half of the year, in the _advance portion of the storm_, and falls when it passes off again; and the reverse is true, as we have seen, when its range is very high in summer. It is, therefore, to some extent, a useful auxiliary, although of minor importance. _The hygrometer_ is of less importance still. It is not in general use as a practical guide to the changes of the weather, and does not deserve to be. A question, which has been much mooted, deserves a passing notice in this connection--viz., whether our climate has gradually become ameliorated and milder on the eastern part of our continent, since its settlement. I have not space left for its discussion. Humboldt (Aspects of Nature, page 103) is of opinion that there has been no material change. He says: