property, viz. on land, negroes, stock, &c. This, as it respects an estate in Virginia, with which I am very well acquainted, I am enabled to do, and will do. We have a road-tax besides, but it is, light, and, in most of the States, paid by a contribution of labour, which rarely exceeds two days in the year, for each male labourer. Dutiable articles is a distinct tax, the quantum of which depends, upon the consumption, upon the disposition of the consumer: with the aid, therefore, of the laws (which I sent you) every man can calculate, better than I am able to do for him, the amount of his own expenditures in this way. An additional duty, or excise, was imposed last session; and this, being now sent, will, if I am not mistaken, (with what was mentioned in my former communications,) bring every tax, direct and indirect, to your view, to which property, in this country, is subjected, either by the general government, or the laws of the States of Pennsylvania, Maryland, and Virginia, to which the observations have been confined.

Beef, and other meats, grain of all sorts, and flour, butter, cheese, and other things, in quantities to make them an object, are always, I conceive, in demand; and are sought after by the purchasers. The sale of lesser articles, at a distance from market-towns, may sometimes stick on hand, but rarely, I believe, forego a sale, if they are worth the transportation.

Sheep thrive very well in the middle States, though they are not exempt from diseases, and are often injured by dogs; and more so, as you approach the mountains, by wolves. Were we to use horses less, and oxen more, on our farms (as they do in the New England States), we should, unquestionably, find our account in it; yet, strange as it may seem, feu are in the practice of the latter; and none push the raising of sheep to the extent they might, and ought to do. The fact is, we have, in a manner, every thing to learn that respects neat and profitable husbandry.'

To one of the President's letters, are subjoined Observations on a letter from Mr. Young to his illustrious correspondent, by Mr. Peters, who is said by General W. to be a theorist and a man of humour.' After having invited Mr. Young to come among them, Mr. P. jocosely enforces his request by thus describing the state of American society:

We have no princes, to indulge the grades more immediately beneath them, in their pleasures and their passions, that they may themselves be supported at the expence of the nation, in their schemes of ambition and luxury-no over-grown nobles, to wanton on the hard earnings of an oppressed yeomanry! He will find a respectable clergy, chosen by their respective congregations, and reputably supported by the voluntary contributions of their hearers. But these are not ecclesiastical drones! - fruges consumere nati :-they do, themselves, the duties required of them! they act not in the affairs of heaven by deputies, whose poverty is truly apostolical; the penurious stipends allowed them by their grasping superiors, compelling them to be conversant only in the fasts, while their principals revel in the feasts, of the church. In a word, he will not see a sable host

of superfluous and pampered priests (maintained by numbers who do not hear, or believe in their doctrines), who fatten on the property of the people; and, while they fetter and terrify men's consciences, to mould them to their purposes, eat out their substances, under the sanction of law. These descriptions of characters, in other countries, create and increase taxes; while they render their subordinates less liable to pay them, by enormous rents, made necessary by their dissipation and extravagance, and by their capricious terms of leasing lands, of which they are the principal engrossers. England has, perhaps, less reason to complain, on these accounts, than some other European countries: but, if we had no other statements to rely on than those given by Mr. YOUNG himself, we should know enough to be convinced, that, even there, some of these causes produce misfortunes in sufficient plenty. Not having the least inclination, if it were in my power, to disturb the systems of other nations, and wishing the happiness of mankind in their own way, I do not men tion either our positive or negative prosperity, with a view to draw odious or disagreeable comparisons. The world will never agree about forms of government. Let those who think well of grades in society, be happy in the possession of such arrangements. We con sider it fortunate, and feel it beneficial, that we have them not.'

The correspondence concludes with an account of four farms, containing in the whole 3260 acres, which General W, seemed solicitous of letting to European tenants. He, indeed, indirectly insinuates a wish that Mr. Young himself might be tempted across the Atlantic. We shall give the General's own words, in order to shew the delicate manner in which he manages the subject:

I shall now conclude as I began, with a desire, that if you see any impropriety in making these sentiments known to that class of people who might wish to avail themselves of the occasion, that it may not be mentioned. By a law, or by some regulation of your government, artisans, I am well aware, are iaid under restraints; and, for this reason, I have studiously avoided any overtures to mechanics, although my occasions called for them. But never having heard that difficulties were thrown in the way of husbandmen by the government, is one reason for my bringing this matter to your view. A second is, that having yourself expressed sentiments which shewed that you had cast an eye towards this country, and was not inattentive to the welfare of it, I was led to make my intentions known to you, that if you, or your friends, were disposed to avail yourselves of the knowledge, you might take prompt measures for the execution.-And, 3dly, I was sure, if you had lost sight of the object yourself, I could, nevertheless, rely upon such information as you might see fit to give me, and upon such characters, too, as you might be disposed to recommend.'

No intimation is given that any success attended this application; and indeed we are confident that Mr. Young never felt any inclination to exchange Bradfield Hall in Suffolk for

either

either Dogue Run or Muddy-Hole farms, which the President proposed to let to him, or any discontented English farmer.

ART. III. Experiments upon the Circulation of the Blood, throughout the Vascular System: On languid Circulation: On the Motion of the Blood, independent of the Action of the Heart: And on the Pulsations of the Arteries. By the Abbé Spallanzani. With Notes, and a Sketch of the Literary Life of the Author; by J. Tourdes, M. D., of the University of Montpellier, and one of the Physicians to the French Army in Italy, &c. Translated into English, and illustrated with additional Notes; by R. Hall, M. D., &c. 8vo. pp. 430. 9s. Boards. Ridgway. 1801. THE name of the industrious author of these experiments

is associated with so many interesting recollections, that our readers will probably be glad to see a few brief particulars concerning him, extracted from the memoirs prefixed to this Volume.

Lazarus Spallanzani was born at Scandiano, near Reggio, Jan. 12th, 1729; and his father was an advocate. He studied first at Reggio, and afterward at Bologna; where experimental philosophy was taught by his cousin, a distinguished woman, Laura Bassa. He displayed early talents, especially in researches concerning Natural History; of which his observations on the Origin of Fountains, and his dissertation "De lapidibus ab aqua resilientibus," are remarkable proofs. At twenty-six years of age, he was appointed professor of philosophy and belles lettres at Reggio, and he held this situation during six years. At the age of thirty-three, he removed to Modena ; and at this time he published his treatise on the reproduction of animals. In 1770, he was invited to fill the chair of Natural History at Pavia; and here he commenced that brilliant. career which has gained for him so high a place among modern philosophers. In this part of the memoirs, Dr. Tourdes has given a concise and perspicuous view of the author's principal works. The world was deprived of this eminent man in Feb. 1798; when an apoplexy, conjoined with enlargement of the prostate gland, and considerable disease in the bladder, brought him to the grave.

Mo-y.

As a particular view of the numerous and interesting experiments here detailed would lead us into a discussion of too great length, we shall present our readers with parts of the summary of them which is given by Dr. Tourdes. It may be necessary to premise, however, that Spallanzani accounts for the diversity between some of his observations and those of REV. AUG. 1802. Haller,

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Haller, from the circumstance of his having examined the mesenteric vessels in situ, while Haller previously extended

them on hooks.

1. The heart does not entirely empty itself in the systoleHaller thought otherwise. He conceived that if any portion of the blood remained in the cavities of the heart, it would, by a continued excitement, oppose the state of diastole; but Felix Fontana has justly observed that the blood which then remains in the ventricles, cannot preserve in activity the contractile force which they possess.

2. Does the blood flow with an uniform velocity from the heart to the most distant extremities of the arterial branches?-On considering the nature of this fluid, the canals through which it flows, their flexures, angles, unequal diameters, &c., we might, at first, be induced to conclude that the velocity of the blood must decrease in proportion to its distance from the heart; this, at least, is the consequence which would result from a strict application of the laws of Hydraulics to the animal economy. Haller suspected that this application was false; and he founded his opinion principally on the almost equal velocity observable in the largest arteries and the smallest veins. If it be true that the motion in the latter is equally rapid as in the large arterial trunks, we cannot but suppose, that the velocity is not diminished in arteries of the same diameter with the smallest veins. This, however, was but mere conjecture, until the experiments of our author converted it into a reality. He found that the blood invariably circulates with equal rapidity in the large and middlesized vessels; that it loses nothing of this rapidity in the very smallest; and that the angles and curvatures, whether natural or artificial, neither augment nor diminish its momentum. The circulation, however, is not entirely uniform throughout the whole of its course; close to the heart the blood experiences an alternation of motion and rest, corresponding to the systole and diastole of that organ. In proportion as it recedes from the heart, this alternate change disappears; the blood flows more rapidly during the systole; and it proceeds with the same degree of velocity to the very extremities of the arteries.'

3. The arteries are transformed into veins in various ways. Some of them, in becoming veins, bend back their course immediately towards the heart; others, previously, form a thousand doublings and windings. While one anastomoses directly with a vein; another communicates with it only through an intermediate tissue. Here an artery branches into a variety of veins; and there a number of arteries unite in a single vein.'

4. It was farther supposed, though more from theoretic reasoning than observation, that the venous blood accelerates its motion as it approaches the heart. Haller could easily observe that the blood circulated in the trunk of a vein with greater rapidity than in the branches which open into it. But a single fact was not sufficient to establish a general law.-Spallanzani made a great number of experi ments upon this subject. On a careful examination of several veins throughout the whole of their course, he perceived that the circula

tion

tion increases in proportion as the venous vessels enlarge their diameters, admit a greater quantity of blood, and more nearly approach the heart. The result of his enquiries into the ratio of this velocity was, that in the large vessels it scarcely exceeds by one third that of the smallest.'

Does the momentum of the blood depend entirely on the action of the heart? Such was the Professor's opinion; of the truth of which he was so firmly convinced himself, that he conceived he should convert the most incredulous of his readers. It is certainly a matter of surprize that he, who had so often seen the blood circulate, with rapidity and regularity, in vessels separated from the heart by ligature or division; who had ascertained the existence of a distinct action in the arteries and veins; who attacked, with so much force of reasoning, the too general theory of Harvey; and who combated, by the most direct arguments, the doctrines of the Mechaniciansshould, yet, have adopted an opinion so favourable to their hypothesis, so contrary to the result of his own experiments, and even so opposite to the title of one of his dissertations-" The motion of the blood, independent of the action of the heart."—

Haller is the only physiologist who has collected the various phenomena of languid circulation; that is, when it is on the point of entirely ceasing. From being, at first, strong and rapid, according to his account, it suddenly diminishes its velocity, becomes irregular, makes a retrograde movement, oscillates, and finally stops altogether;-Spallanzani, however, asserts, that all these irregularities proceed from the mode of experiment adopted by Haller; that the blood is sensibly diminished in velocity at the commencement, then abates its current by little and little, and, at last, becomes stationary in a gradual and insensible manner, without ever exhibiting, in a natural state, any oscillation, or retrograde movement.' —

The globules of the blood float in an invisible and elastic fluid. Their figure is nearly spherical, and they are elongated or compressed, according to the diameter of the vessel through which they pass.'

These extracts contain the principal points on which the author differs from preceding physiologists. Our readers must consult the book for the proofs by which his doctrines are supported.

The Abbé seems to be of opinion, (p. 299,) that the red globules of the blood possess elasticity: but he has only been able to observe an appearance of it in one instance. The researches of the ablest modern physiologists have left so many curious questions undecided respecting the great process of circulation, that a wide field for inquiry still remains. On the subject of the globules of the blood, we beg leave to refer our readers to some curious observations by Mr. Cavallo, in the appendix to his treatise on the Medical Properties of Factitious Airs, which were cited in our Review, vol. xxxii. N. S. p. 146, &c.

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