thor's juvenility, without impeaching the rectitude of his main defign, and general plan. Other little faults may also be found, which, however, are not of fufficient moment to deserve our particular mention; and may only serve to shew our author's disregard of that laborious correctness neceffary to the character of a finifh'd performance. We look upon the work, taken altogether, as well deferving our recommendation. The principles which the author every where aims to inculcate by the moral of his fable, and the conduct and characters of the perfons introduced into it, are juft, honourable, and amiable: fo that, if fome parts of his work are only intended to divert the reader, yet others can fcarcely fail of improving him. He paints the virtues of humility, modefty, gratitude, prudence, generofity, courage, love of our country, and piety towards God, in their natural and attractive colours. On the other hand, he has justly ridiculed fome reigning follies, and feverely expofed and lafhed many vices of the times. But the merit of this work confifts less in the entertainment it may afford as a novel, or the satisfaction it may give to the lovers of fatire, than in those parts where the author digreffes into useful leffons of morality, and where he introduces certain converfation-pieces; from whence his younger readers may draw proper hints for their improvement in politenefs, humanity-in fine, in the art of meriting and acquiring the refpect, and the love of mankind.

In the firft volume we have some admirable rules for the education of youth, especially young gentlemen: in the fecond volume the author makes fome agreeable excurfions into the political province ; where he takes frequent occafion of fhewing his attachment to the prefent government. In fhort, we may fay of this work, what the author himself fays of the school-master's plan in the first volume, That inftruction and profitable entertainment are here fo agreeably and nicely blended, that the one is never fuffered to become tedious and irksome, nor the other to cloy or fill the mind too much.'

After thus giving the hiftory of Jack Conner its due praise, we must however remind our readers, that we have faid it is not free from faults; that the author has fome levities and innacuracies to anfwer for: tho' these are probably thrown out only to engagé, or rather to entrap, the generality of readers, into the more ufeful and moral parts of the work. He has alfo abruptly drawn in feveral stories, no way effential to his plan, or the main bufi

nefs

nefs of his fable. But whatever imperfections he may be charged with, he seems himself to have been fenfible of them, when he chose these lines of Mr. Pope for his motto.

Whoever thinks a faultless piece to fee,

Thinks what ne'er was, nor is, nor ne'er fhall be.
In ev'ry work, regard the writer's end,
Since none can compass more than they intend;
And if the means be just, the conduct true,
Applaufe, in fpite of trivial faults, is due.

We could with pleasure have given fome extracts from this work, but find ourselves fo much in arrear to our readers, by the extraordinary number of the laft winter's publications, that we shall be obliged to give only a characteristical sketch of fome articles to make room for others, where extracts are more effentially requifite.

ART. LV. Continuation and conclufion of Dr. Whytt on the vital and other involuntary motions.

WE

E terminated our account and abstract of a former part of this learned and ingenious work, which the author modeftly terms an Effay, with his fection Of the motions of the pupil, and of the internal ear, in our Review for March laft. That of the alternate motions of reSpiration immediately follows: and as we had formerly obferved from his preface, that an early diffatisfaction with the common theories of refpiration, and the motion of the heart had first determined him to a difquifition of the vital motions, we shall not be furprized to find many of his notions in this section new and peculiar; though, as far as we are capable of judging, the affectation of novelty does not appear to have been the ruling impulfe of our author's diffention, but the love and purfuit of phyfical truth.

Contrary to the opinion of Morgagni, and fome ingenious moderns on this fubject, Dr. Whytt afferts, in a note at the beginning of this fection, that it were eafy to refute the notion of the lungs not being always contiguous to the pleura, and that of internal air being contained between them and it; tho' he judges the formal proof of it foreign to his prefent defign.' We imagine, however, that an evident demonftration of this continual contact would have been acceptable to his medical and chirurgical readers; as the certain recovery of fome few perfons from gun-fhot VOL. VI. wounds,

Gg

wounds, where the bullet has penetrated the cavity of the thorax, would induce us to infer fuch a contraction of the lungs in exfpiration, and fuch a temporary retraction of them from the pleura, as might allow the penetrating bullet, that has divided this, to avoid them. Befides, in dr. Houfton's diffection of a living dog, cited by dr. Hoadly in the appendix to his accurate lectures on refpiration, the lungs, expreffed there by aliquod album, were obferved thro' the denuded pleura, to be applied close to it in infpiration when the breast was dilated; but during expiration, and the coarctation of the breaft, they were obferved to disappear and give way to the afcent of the diaphragm, his corpus rubrum; tho', upon a further denudation of the fuperior part of the pleura, the white body only appeared. As this experiment was made in the prefence of many, autoply here manifeftly favours the notion of the lower part, at leaft, of the lungs receding from the pleura in expiration. Their dilatation, however, which dr. Houston afterwards afferts to have been vifibly fynchronous with the contraction of the thorax, and vice verfa, is very furprizing, and not to be accounted for on any theory of refpiration we have met with. But if it be confidered here, that, befides the agony from diffection, there were at this time two ribs cut through, and a very large aperture made into one fide of the breaft, it is but too inferable, we may be led into very. wrong notions of natural refpiration, if we conclude it, fimilar to what is, fo probably, a violent and convulfive one. And, in fact, comparing this laft phænomenon with the application of the lungs to the pleura in inspiration, which appeared before any irruption into the thorax, it feems a directly inverted and unnatural respiration.

On the other hand, the long detention of the air, fuppofed within the cavity of the breaft, muft tend to leffen its natural fpring too confiderably, to qualify it for contributing much to expiration, which is the principal use the contenders for this internal air aflign it. But as dr. Hales has fhewn the inflated lungs of a calf, when out of the body, to tranfmit fome air thro' a few paffages, if the like obtain in the living man, it has, undoubtedly, its ufe; and there will feem to be a neceflity for fome internal porofities to abforb or carry off any ftale or morbid excess of it, which muft otherwife happen from its accumulation, however gradual. And indeed, if we fuppofe fuch a reception and emiffion of air into and from this cavity, it will be the

better

better qualified to concur as an antagonist to that expelled by expiration.

Some other writers on respiration having fuppofed the external and internal intercoftal muscles to act antagonistically in it, the former co-operating to infpiration, and the latter to expiration, this learned profeffor does not hesitate to limit the action of both to inspiration only, which was alfo Borelli's opinion. He affirms the lungs to be no more capable of felf-expanfion than the bladder of urine, or than an empty bladder, fecurely tied, is capable of inflating itfelf against the preffure of the atmosphere. He fuppofes the contents of the thorax to be in perpetual contact with its internal furface, and with the upper furface of the diaphragm; yet, as he allows the mufculer fibres of the bronchia, and even of the veficles of the lungs, to have the common affection, according to his third principle, of conftantly endeavouring to fhorten themselves, it appears cult at firft to conceive them, in compleat expiration, as not receeding fomewhat from their contact with the pleura: but, as he muft fuppofe the expiratory mufcles to be exerting the fame affection, at the fame inftant, and maintains the motions of the breast and lungs to be not only ftrictly. fynchronous, but alfo equable in proportion, this must confiderably leffen the difficulty, tho' it fcarcely leaves the lungs any proper alternate motions of their own.

diffi

As contrary fentiments, on fome of these particulars, have been promulged by fome writers of reputation, we shall not venture to interfere further here, but proceed to our author's own account of respiration in order to which, he fays, it is only neceflary to fhew, why the intercoftal mufcles and diaphragm are alternately contracted and relaxed; fince their contraction produces inspiration, and their relaxation allows the renitency of the cartilages of the ribs, &c. to effect exfpirations.'

After employing feveral pages then in fuch ftrictures on certain experiments made on living animals, by mr. Bremond, and others, (which feem to discountenance his hypothefis) as appear greatly to impair their force; and many more in fome ftrong objections to Boerhaave's and dr. Martine's theories on refpiration, he proposes his own in the following terms:

1. During infpiration and expiration, the blood finds. an eafy paffage through the veffels of the lungs, as by their alternate inflation and contraction, it is preffed forward to the left ventricle of the heart. After inspiration is Gg 2

completed,

completed, it begins to flow with more difficulty; and at the end of expiration (if inspiration does not foon fucceed) its motion is ftill lefs free. After expiration, therefore, the blood, on account of its difficult paffage through the pulmonary veffels, is partly accumulated in them, and by diftracting their fenfible fibres and membranes, acts as a jtimulus upon the pulmonic nerves, occafioning an uneafy fence of fulness, ftoppage, or fuffocation in the breast, which is more or lefs remarkable, according to the time during which refpiration is ftopt, the capacity of the pulmonary veffels, and the quantity of blood thrown into them by the right ventricle of the heart.'

He adds immediately, that tho' it may seem more wonderful, that the diaphragm and intercoftal muscles should be brought into contractions by a fimulus acting upon the lungs, than that a stimulus fhould alternately contract the heart and alimentary tube, we may affure ourselves of the certainty of the fact, from the ftrongest and justest analogy.' Thus, fays he, for example, if a few drops of water, or any other liquor, by an accident in fwallowing, fall into the trachea, the diaphragm and intercoftal muscles are inftantly called into action, and continue to be agitated with alternate contractions and relaxations, till the stimulating caufe is removed. Again, if a thin pituit fecerned in too great quantity, by the veffels and glands of the bronchia, diftils upon the veficles of the lungs, alternate convulfions of the diaphragm, intercoftal and abdominal mufcles, enfue; which are repeated over and over again, till the irritating caufe is leffened or expelled. In a true peripneumony also, when, by reafon of an obstruction in the pulmonary arteries, the blood paffes through the lungs with great difficulty, a fhort cough is almoft a conftant fymptom. Is it not therefore reasonable to infer, that a less remarkable ftimulus, or an eafy fenfation in the veffels of the lungs, will be followed by gentler contractions of the infpiratory inufcles?

After expiration is finished, the blood beginning to be accumulated in the lungs, will, not only by its quantity diftracing their veffels, but alfo by its heat, occafion an uneafy fenfation, that is, act upon those parts as a ftimulus; in confequence of which the diaphragm and intercoftal muscles are contracted, and infpiration is performed; by which the blood being not only cooled by the external air, but its paffage alfo promoted towards the left ventricle of the heart, the stimulus or uneafy fenfation ceases: hence

thefe