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Climatology of the United States and of the temperate latitudes of the North American Continent, embracing a full comparison of these with the Climatology of the temperate latitudes of Europe and Asia, and especially in regard to agriculture, sanitary investigations, and engineering, with isothermal and rain charts for each season, the extreme months, and the year, including a summary of the statistics of meteorological observations in the United States, condensed from recent scientific and official publications: By LORIN BLODGET, Member of the National Institute, &c. Philadelphia, Lippincott & Co.; Trübner & Co., London, 1857. In the prosecution of meteorological enquiries the United States deservedly hold a high rank. In the collection of meteorological data by fixed stations, as well as by surveying and exploring expeditions throughout the wide area of the union, an enlightened zeal has been ever manifested by the several public departments as well as by private individuals; and in contributions descriptive or explanatory of particular phenomena, the scientific literature of that country has been remarkably fertile. We are not, however, aware that prior to the publication of Mr. Blodget's book any attempt has been made to present to the world in a connected whole the large mass of materials which the industry of so many observers has called into being.

On this account if on no other Mr. Blodget, as pioneer in the work of compilation, merits the thanks of scientific men and of the world at large. His book bears marks of great acumen as well as of industry ; it abounds in important facts and is highly suggestive, and as such well deserves to be recommended for a close and careful examination.

In saying this we do not engage to endorse every opinion entertained by the author. In a science so essentially progressive as meteorology many views must at best be held provisionally, subject that is, to be discarded or to be matured by extended observation. In Mr. Blodget's book we have a stem round which the fruits of future research may appropriately cluster, and glad shall we be if the work of grafting as well as that of pruning should fall to the lot of Mr. Blodget himself.

For the accomplishment of his task the author has brought experience of no common order: the aptness which he had exhibited , for investigations of this kind procured for him some time ago the appointment of superintendent of the reduction of the meteorological observations made under the auspices of the Smithsonian Insti

tution, in which capacity he was enabled to collect a large mass of data; and he has also apparently met with the utmost readiness on the part of the large body of observers throughout the continent to supply him with the results of their labors; so that as regards the temperate latitudes, to which his discussions are chiefly confined, there has been no dearth of materials.

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The general arrangement of the book is clearly set forth in its ample title page: it exhibits the geographical distribution of temperature and of the fall of rain and snow for the temperate regions of North America, it discusses the peculiarities of the two climatological areas into which the continent is divided by the Rocky Mountains, and draws a comparison between these and regions of analogous position in the old world. In conducting these comparisons regard is had to outline configuration, vertical elevation, and other physical features. The whole is illustrated by a series of neatly executed charts, consisting of an isothermal chart of North America for each of the four seasons, and one for the year, together with as many corresponding charts of rain and snow. There is also a temperature chart and a rain chart for the whole north temperate zone, with a profile of comparative altitudes for both hemispheres.

The book opens with an exhibition of the physical data upon which the author's subsequent discussions are based.

These data in the first place consist of the mean temperatures and the depths of rain at a large number of points both in the old and new world, arranged in tables for each month, the four seasons, and the year. In every case where it is practicable the latitudes and vertical elevations of the stations are given, together with the number of years from which the means are derived, and the actual dates at which the series commenced and terminated. For the old and new worlds the tables are arranged in separate groups. Besides the foregoing, for a few stations of importance in the United States at which observations have been continued during a long series of years, additional tables are given separately for each station, showing the monthly and annual mean temperatures, with the precipitation of rain and snow for each year that the period embraces.

Following the above mentioned and strictly meteorological details, which occupy the whole of the first chapter to the extent of about eighty pages, is a chapter on physical geography, which includes, in a tabular form, the vertical topography of the country east of the Rocky Mountains, arranged in belts perpendicular to the general direction of the Alleghanies. Another list for the regions west of

the Rocky Mountains is also given, arranged in meridional belts 5o in width from the 100th meridian westward.

In instituting a comparison between the old and new worlds, with respect to their physical geography, the author considers that there are features now sufficienly apparent in North America which hitherto have been considered as peculiar to the older continents.

"The great point of interest lies in the new features of our physical geography, or in the views which differ so far from those previously held, as to require a change in all deductions based upon surface and vertical configuration, as all those of climatology must be to some extent. The most important of these recent deter minatious is that of a much greater altitude for the western interior than was before assigned to it, and that high and arid plateaus and basins exist in nearly as great a proportion to the general area of the continent as in Asia and Europe. There are conditions of surface and configuration similar to those which have been thought peculiar to Europe and Asia belonging to great regions here, and we are to look for correspondence in climate, and in vegetable and animal life, and if this last does not now exist, we ascertain such a correspondence to be possible, and may adapt our practical interests accordingly. Guyot, and other writers on physical geography, have contrasted the temperate latitudes here with those of Europe and Asia, in the view that this is wanting in the high desert plateaus of these, and assuming for this less altitude, a greater proportion of plains, and, consequently, the analogies of sea climates in contrast with the extreme continental peculiarities of Asia. Our recent surveys have shewn that lofty plateaus, lofty mountains, and extended districts of the most extreme continental character, exist here in nearly the same relation to the whole mass of the continent as in the old world, and the comparison of the two thus becomes much more direct and more necessary than before, as essential to a proper understanding of our climatology. In short we may compare the two as mainly equal and similar in the physical features of surface and configuration, and we must do so to correctly estimate the consequences upon climatology, which are always most directly dependent on physical geography." pp. 84, 85.

The Alleghanies have been often considered as forming a line of demarcation between two very different climatological areas: it would , seem, however, from more recent investigations, that the elevation of these mountains has but little influence in interrupting the uniformity of climate, excepting in the moderate degree produced by altitude alone, and that it is the Rocky Mountains that we must regard as the true barrier between two regions climatologically distinct.

"The great chain of the Rocky Mountains is next in the surface configuration, and from this point forward all the uniformity belonging to the Eastern United States disappears, and the greatest and most abrupt contrasts occur. As in the north of India and in other parts of Asia, everything here depends on configuration and surface; and not only on these directly, but also on the relation of any point or locality to an extreme of configuration in the vicinity. Thus the valleys

of California are mainly controlled by the mountains near them, and if shut from the sea have arid climates, and, perhaps, a denuded, sandy, or alkaline surface; when if open to sea influences the reverse conditions prevail. These remarks apply more particularly to Oregon and the coasts north of the 35th parallel, than elsewhere, as the coast of Lower California is arid at all exposures." pp 88, 89.

This climatological division is again insisted on in the opening paragraph of the following chapter, descriptive of the general character of the Eastern United States.

"It is necessary to make a distinction of a very decided character between the parts of this continent separated by the Rocky Mountains, though the idea of this distinction has hardly yet entered into the received views of the North American climate. It is still described under the characteristics which belong only to the area east of the great plains, and the homogeneous character belonging to much of this great extent of surface is that recognized in Europe as the North American climate. Now that we have found this to differ so extremely from the interior and Pacific districts, it is necessary to describe it separately and to designate it as the eastern area of the United States.

So recently as the production of Guyot's able work on comparative physical Geography (Guyot's Earth and Man), the distinction made between the old world and the new was to assign to the new oceanic, and to the old world continental climates; the prevailing character of the Eastern States and the Mississippi Valley being taken as the type of the whole country. The great expanse of these plains gave reason for this distinction, in the then unknown condition of the interior and Pacific coast, but it is now clear that the proportion of arid and continental districts and climates is as great here as in the old world. The position of the plains exposed to oceanic influences is reversed, however, and instead of the extensive low areas belonging to the west of Europe our western coast is very narrow, and the Mississippi plain is, to some extent, the equivalent of the European plain.

But the climate of the Mississippi Valley or plain, and of the eastern side of the continent generally, is not oceanic strictly; and it differs radically from the oceanic climates of the west of Europe. It has its equivalent only in a similar continental position, or in China; which is, unfortunatly, too little known to aid the illustration much. As a whole, the North American continent differs little from the old world, except in the comparative areas embraced by the several divisions. Our oceanic districts on the west are very narrow and unimportant compared with the immense and fertile areas of like position and climate in Europe; our interior and extreme districts are differently placed from those of Asia, but in other respects they differ little; our eastern areas, which are properly neither interior nor oceanic, are comparatively larger and more important because of the existence here of a great interior plain opening southward to the tropical heat and moisture, and partaking to some extent of tropical peculiarities.

The early distinction between the Atlantic States and the Mississippi Valley has been quite dropped as the progress of observation has shewn them to be essentially the same, or to differ only in unimportant particulars. It is difficult to designate any important fact entitling them to separate classification; they are alike subject to great extremes and to the same extremes, they both have marked

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continental features at some seasons, and decidedly tropical features at others, and these influence the whole district similarly, without showing any line of separation." pp. 125, 126.

One of the principal features alleged as belonging to this area, as a whole, is its adaptation to a great range of vegetable and animal life; another feature consists in this, that the whole area is in communication as regards its atmospheric changes: any agency that affects one point producing a corresponding though not necessarily a simultaneous, or equal, or even similar change throughout the area. In the words of the writer:

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"As an associated feature of the uniformity just alluded to, the changes of temperature, and the oscillations of every sort, strike over the Eastern United States as changes would over any plane surface; that is they are symmetrical and uniform, and knowing what they are at a few places we may easily infer what they have been at all. Thus, if a degree of cold occurs at St. Louis on one day, and at Philadelphia two days afterwards, or at any interval whatever, we may be certain that the whole intervening district has been similarly affected. So of a barometric depression or variation, or of a great storm, or of particularly severe winds. Though the changes occurring in one part may not be felt at an opposite point,— as, though it may be twenty degrees below the average temperature for any period at Charleston, it may be as much above that mean at Albany or Montreal-the conditions, whatever they are, affect the intervening districts symmetrically, and are participated in at all places according to the distance from the extreme points. This may be the case to some extent in other climates, or it may be so with some of the great changes, but here it is characteristic of all, and it contrasts extremely with the abrupt transitions, and the predominance of local changes in Southern and Central Europe, and on the west side of this continent as far as known." p. 129.

This chapter abounds in matter for reflection, but as somewhat copious extracts have been already made from it, we must commend it to the study of those specially interested in the subject, and content ourselves by quoting one more passage in which the general type of a storm is described. The description we leave to the rience, or to the future observation of our readers, to verify.

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"Beginning at the northwest, or near Fort Snelling, the general succession of phenomena in the change from calm, average conditions, to the restoration of such conditions again, is something near the following: first, an increase of temperature with winds from the south, south-west or south-east, of duration proportioned to the measure of the change that is to occur, or of from one to four or five days; a fall of barometer; a rain with cast, north-east, or south-east winds during the first half of its duration; a sudden change of wind to some westerly point with a rapid reduction of temperature, high winds and a rising barometer; and, in conclusion, a period of comparatively cold and clear weather. The nucleus or central area of this phenomenon, regarding it as a whole, or, as it may be done for illustration as

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