We will venture to say that there is no country in the world, a knowledge of the Medical Geography of which is so important as that of the United States of America;-and yet of no one is there such ignorance, in other countries, on the subject. To the European emigrant it is a question of momentous interest, for him to ascertain with tolerable accuracy, in what quarter of the Union he .can best locate himself, with a due regard to the preservation of the health of himself and family, and at the same time to the furthering of his views of money making, by mechanical or commercial pursuits in the city, or, a more frequent and probable supposition, by farming in the country. But not alone to foreigners is this inquiry one of interest. To the native citizen it is of equal importance. By inclination more than necessity the inhabitants of these United States are roving, restless, and migrating. Ever intent on bettering their condition, they are constantly on the alert to move to a section of country reputed to have a more fertile and cheaper soil and a finer climate-though the latter is too often a mere secondary consideration. In these migrations, however, change is not sought for as a means of evading labour and toil, in the hopes of enjoying an El Dorado without any personal risk or exercise of ingenuity. On the contrary, the rovers are often tempted by a mere love of adventure, a restless desire of change for the sake of variety alone. Hardly is a person who has left Virginia well settled in Kentucky, before he is seized with a longing to go to Missouri or Alabama, and if he feels himself tolerably comfortable in his second move, will, not unwillingly, attempt a settlement still further west and take a peep at the Aberagoins' as a member of the legislature (no matter of what State) once called the Aborigines; and perhaps join them in hunting and trapping one season and, fight them the next. There are sets, or currents we might call them, of emigration from VOL. IV.-A

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different quarters along the sea board in a westerly direction. The New Englander takes his course for Ohio and Illinois, or the Michigan Territory; the Virginian, who used to be content with moving to Kentucky, now makes it, half the time, a mere reconnoitering ground, from which he takes a fresh departure for Missouri, Alabama or Louisiana.

These are only some of the changes of place and climate sought after by our fellow citizens. Others more numerous but temporary, are of nearly annual occurrence to a large number of all classes. An inhabitant of a district on one of the head waters of the Alleghany River in the State of New York, will be seen in Louisville, or even New Orleans selling the timber, which, as a raft he had floated first into the Ohio and finally down the Mississippi: he making his way home as best he may. In former times this was an affair of infinite toil-now, thanks to steam-boating, he finds it an easy matter.

Merchants-store keepers travel from all parts of the Union to the Atlantic cities, Philadelphia, New York and Baltimore to purchase goods going through, in the journey, as great a change of climate, as would the Italian travelling to Moscow, or the Spaniard to Denmark. We have seen one of these gentlemen from the Arkansas Territory making his investment of goods in Market street, with as quiet methodical and unpretending a manner as if he had just left his store, a few miles out of town. A person in London whose home was upwards of 1200 or 1500 miles distant, would be one of the lions of the day-no matter what his pursuits or modicum of intelligence: but here we are used to such things.

The meeting of the National Legislature or Congress, is another means by which persons, in leaving their homes, often undergo great changes in locality and climate. The representatives from Maine and New Hampshire are in a southern climate at Washington.-Those from Georgia and Louisiana may complain of the cutting easterly, and frozen air of the north in that city.

Conventions of a religious character in some one or other of the Eastern cities, bring persons together from remote and opposite quarters of the Union, and are the means of subjecting them to often trying changes and vicissitudes of climate.

Nor ought we to omit a notice of another not less interesting and beneficial annual convention of persons, young indeed, but ardent in the pursuit of a knowledge, which not solitary nor selfish in its application and enjoyment, is to be usefully applied to saving the lives and preserving the health of their fellow men. We of course allude to the medical students, who come on every winter to attend lectures, and study anatomy and practical surgery and medicine. We see them to the amount of many hundreds every year in Philadelphia-from all parts not only of the Union but of North America. It has fallen to our lot in one season to have under our own immediate charge a young gentleman from Nova Scotia and another from Trinidad di Cuba, while pursuing their medical studies in this city.

Another numerous class of rovers yet remain to be mentioned.

Temperature of the Interior of the Earth.

3

They are travellers for health and pleasure; and in some respects they are entitled to a more conspicuous notice and friendly advice than the others whom we have enumerated. Many of them are females-wives, sisters or daughters, who leave behind them the close and heated and too often unhealthy atmosphere of the Carolinas, Louisiana and Mississippi, to inhale a purer air and enjoy the scenery, and partake of the amusements of the North. Some hie them to the mountains and drink health from the famous springs of Virginia, and others hoping to make a league between fashion and health visit Saratoga and the Lakes-while a third set keep along the shore inhaling the fresh breeze from the Ocean and bathing in its briny waters. Many of these travellers discover after a time, that the change of place and scenes, the long, long distance. from home, does not realise all their fervid hopes; and some are not a little chagrined to find that they may without due care, contract in Pennsylvania and in the fashionable tour through New York, fevers so near akin to those of their own part of the country as not to be distinguishable from them. Fever and ague and remittent bilious fever, are not the products of the soil south of the Potomac alone. Wherever flows a broad river, with its wide meadows and low grounds, or wherever sluggishly steal along streams through marshes and loam and clay, there may these diseases be looked for in the autumnal months by those who heedlessly expose themselves to the night air, and infringe on the rules of temperate living. Yet another evil awaits the traveller from the south when he reaches our north-eastern coast-if his lungs be weak, he must dread the eastern blast which brings with it catarrh, homoptysis or spitting of blood, and, more than all, fell consumption in its train.

But what more of Medical Geography we have to lay before our readers, and much remains, must be postponed for future numbers of our Journal. We have only been able, in fact desired little more on this occasion than to show how deep and wide the interest in the subject ought to be among the inhabitants of these United States.

TEMPERATURE OF THE INTERIOR OF THE EARTH. The heat discovered at considerable depths from the surface of the earth, must have some other origin than the sun. The heat produced by solar rays only makes its way to a certain depth through the material of the earth, and escapes from the surface by radiation; and so nicely balanced are the quantities received and radiated, that at the end of the year no sensible trace remains of these calorific impressions.

The mean temperature of the year undergoes no permanent change, though it may oscillate from one year to another within certain narrow limits. "Below the surface the heat descends very slowly, and the diurnal and annual variations are only sensible at inconsiderable depths; at greater depths the temperature is nearly uniform, and equal to the mean temperature of the year at the surface."

4 Deaths from Cholera for the last ten years in Philadelphia.

Observations have been regularly made for a length of time, of the temperatures of spots at some distance below the surface of the earth. At Paris they have been continued uninterruptedly during the last fifty years in the caves under the Observatory. The thermometer is placed at the depth of nearly 31 yards, under the surface in a bed of fine sand-and during the last 33 years in which it has been observed by Bouvard, it has indicated no change of temperature, or at least its oscillations have not exceeded the 1-33 of a centesimal degree. It has been found that the constant temperature which it marks is 21-6 deg. Fahrenheit more than the mean temperature of Paris at the surface. The difference here is dependent necessarily on other causes than solar heat-and estimating successive increases at greater depths at the same rate, we should arrive at the temperature of boiling water at the depth of 2542 yards below Paris.

But the rate of augmentation of heat in the temperature of the earth, is not by any means determined in a positive manner. "With a view to the more accurate determination of this important element, M. Cordier himself, (Professor of Geology in Paris,) with a perfect knowledge of all the precautions necessary to be used, undertook to examine the temperature of several coal mines in France. At Carmeaux, the mean of his observations gave 21 yards as the depth corresponding to an increased temperature of 1°. of Fahrenheit, at Littry 11 1-2 yards, and at Decise 9 yards, results far from presenting a satisfactory coincidence." "The mean of a great number of observations made in the mines of Cornwall and Devonshire, by M. W. Fox, and published in the Philosophical Transactions of 1821, and 1822, gives 15 yards as the depth, corresponding to an increase of 1° Fahrenheit. In the coal mines of Brittany, the same mean depth is found to be 25 yards; at Bex, in Switzerland, 15 yards; in Saxony, 24 yards; at Guanaxato, in America, 16 yards. M. Cordier, considers that 15 yards may be provisionally assumed as the average depth to an increase of 10 Fahrenheit."

DEATH'S FROM CHOLERA FOR THE LAST TEN YEARS IN PHILADELPHIA.

In the Reports of the Board of Health, from which the above statement is made, the disease in infants is usually designated by the term Cholera Infantum, that in adults, as Cholera Morbus.

-reasonable

-stupid.

Sullen ColdUnfeeling Quite This very useful scale is earnestly recommended to all heads of families, to be hung up in a conspicuous part of the house. The use of it is to ascertain the degrees of restraint and improvement which have been effected in the human temperature, and its changes. Those who would derive full benefit from it, should imitate the diligence of the natural philosophers, who keep meteorological diaries, by entering in a journal every variation observed in their own tempers or that of their friends. They will thus be enabled at any time by looking back to former entries, to see what measure of improvement has been gained in a given period, as well as to discover, by comparing the entries in the moral with those in the meteorological journal (with which the newspapers from time to time favour us) whether that which is said to affect so powerfully the human temper, the state of the atmosphere, does indeed cause all the alterations we remark. Thus, for instance, when in excuse for a fit of passion in July, or of a peevishness in October, the heat or dulness of the weather is pleaded; if by referring to February, or to some bright cheerful day in April, an entry of the same kind is found, it may be very safely concluded, that the weather is not

alone in the fault.

We recommend the moral thermometer from having known it to be used in numerous instances with great advantage. An individual whose temper always pointed to the degree of sullen in the morning when he met his family at the breakfast table, and on returning from a select party of his friends at night, rose to some one of the degrees above hot, was induced to investigate the cause of these strange phenomena, and arriving at the truth, was enabled to effect such a reformation in himself, that for many months on a stretch his temper and habits remained temperate, or rose only to the degree marked warm but reasonable. A gentleman who made use of the scale, finding by his diary, that while in the first hours of the day his temper was tolerable cool and even, it sunk after his meridian luncheon and cheerful glass to dull, and after a late dinner got so low as quite stupid, effected so complete a change in his