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thor's juvenility, without impeaching the rectitude of his main design, and general plan. Other little faults
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 necessary to the character of a finish'd performance. We look upon the work, taken altogether, as well deserving 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 persons introduced into it, are just, honourable, and amiable: so that, if some 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, generosity, cou. rage, love of our country, and piety towards God, in their natural and attractive colours. On the other hand, he has justly ridiculed some reigning follies, and feverely exposed and lashed 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 satire, than in those parts where the author digresses into useful lessons of morality, and where he introduces certain conversation-pieces; from whence his younger readers may draw proper hints for their improvement in politeness, humanity-in fine, in the art of meriting and acquiring the respect, and the love of mankind.
In the first volume we have fome admirable rules for the education of youth, especially young gentlemen : in the second volume the author makes some agreeable excurfions into the political province ;'where he takes frequent occasion of thewing his attachment to the present government. In short, we may say of this work, what
the author himself says of the school-majter's plan in the first vo. lume, That instruction and profitable entertainment are here so agreeably and nicely blended, that the one is never suffered to become tedious and irksome, nor the other to cloy or fill the mind too much.'
After thus giving the history 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 some levities and innacuracies to answer for: tho' these are probably thrown out only to engagé, or rather to entrap, the generality of readers, into the more useful and moral parts of the work. He has also abruptly drawn in several stories, no way essential to his plan, or the main busi
ness of his fable. But whatever imperfections he may be charged with, he seems himself to have been sensible of them, when he chose these lines of Mr. Pope for his motto.
Whoever thinks a faultless piece to fee,
We could with pleasure have given some extracts from this work, but find ourselves so much in arrear to our readers, by the extraordinary number of the last winter's publications, that we shall be obliged to give only a characteristical sketch of some articles to make room for others, where extracts are more essentially requisite.
ART. lv. Continuation and conclusion of Dr. Whytt on
the vital and other involuntary motions. W
E terminated our account and abstract of a former
part of this learned and ingenious work, which the author modestly terms an Essay, with his section Of the motions of the pupil, and of the internal ear, in our Review for March last. That Of the alternate motions of reSpiration immediately follows: and as we had formerly observed from his preface, that an early dissatisfaction with the common theories of respiration, and the motion of the heart had first determined him to a disquisition of the vital motions, we shall not be surprized to find many of his notions in this section new and peculiar ; though, as far we are capable of judging, the affectation of novelty does not appear to have been the ruling impulse of our author's dissention, but the love and pursuit of physical truth.
Contrary to the opinion of Morgagni, and some ingenious moderns on this subject, Dr. Whytt afferts, in a note at the beginning of this section, that it were easy 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 present design. We imagine, however, that an evident demonstration of this continual contact would have been acceptable to his medical and chirurgical readers; as the certain recovery of fome few persons from gun-shot Vol. VI.
wounds, where the bullet has penetrated the cavity of the thorax, would induce us to infer such a contraction of the lungs in exspiration, and such a temporary retraction of them from the pleura, as might allow the penetrating bullet, that has divided this, to avoid them. Belides, in dr. Houlton's diffection of a living dog, cited by dr. Hoadly in the appendix to his accurate lectures on respiration, the lungs, expressed there by aliquod album, were observed thro' the denuded pleura, to be applied close to it in inspiration when the breast was dilated; but during expiration, and the coarctation of the breast, they were observed to disappear and give way to the ascent of the diaphragm, his corpus rubrum; tho', upon a further denudation of the superior part of the pleura, the white body only appeared. As this experiment was made in the presence of many, autopsy here manifestly favours the notion of the lower part, at least, of the lungs receding from the pleura in expiration. Their dilatation, however, which dr. Houston afterwards asserts to have been visibly synchronous with the contraction of the thorax, and vice versa, is very surprizing, and not to be accounted for on any theory of respiration we have met with. But if it be considered 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 breast, it is but too inferable, we may be led into very wrong notions of natural respiration, if we conclude it similar to what is, fo probably, a violent and convullive çne. And, in fact, comparing this last phanomenon with the application of the lungs to the pleura in inspiration, which appeared before any irruption into the thorax, it seems a directly inverted and unnatural respiration.
On the other hand, the long detention of the air, supposed within the cavity of the breast, must tend to lessen its natural spring too considerably, to qualify it for contributing much to expiration, which is the principal use the contenders for this internal air allign it. But as dr. Hales has shewn the inflated lungs of a calf, when out of the body, to transmit some air thro' a few pasiages, if the like obtain in the living man, it has, undoubtedly, its use ; and there will seem
to be a necellity for some internal porofities to absorb or carry off any stale or morbid excess of it, which must otherwise happen from its accumulation, however gradual. And indeed, if we suppose such a reception and emission of air into and from this cavity, it will be the
better qualified to concur as an antagonist to that expelled by expiration.
Some other writers on respiration having supposed the external and internal intercostal muscles to act antagonistically in it, the former co-operating to inspiration, and the latter to expiration, this learned professor does not hesitate to limit the action of both to inspiration only, which was also Borelli's opinion. He affirms the lungs to be no more capable of self-expansion than the bladder of urine, or than an empty bladder, securely tied, is capable of inflating itself against the pressure of the atmosphere. He fupposes the contents of the thorax to be in perpetual contact with its internal surface, and with the upper surface of the diaphragm ; yet,
as he allows the musculer fibres of the bronchia, and even of the vesicles of the lungs, to have the common affection, according to his third principle, of conftantly endeavouring to shorten themselves, it appears dificult at first to conceive them, in compleat expiration, as not receeding somewhat from their contact with the pleura: but, as he must suppose the expiratory muscles to be exerting the same affection, at the same instant, and maintains the motions of the breast and lungs to be not only strictly · synchronous, but also equable in proportion, this must considerably lessen the difficulty, tho' it scarcely leaves the lungs any proper alternate motions of their own.
As contrary sentiments, on some of these particulars, have been promulged by some 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 says, it is only necessary to fhew, why the intercostal muscles and diaphragm are alternately contracted and relaxed; since their contraction produces inspiration, and their relaxation allows the renitency of the cartilages of the ribs, &c. to effect exspirations.'
After employing several pages then in such strictures on certain experiments made on living animals, by mr. Bremond, and others, (which seem to discountenance bis hypothesis) as appear greatly to impair their force; and many more in some strong objections to Boerhaave's and dr. Martine's theories on respiration, he proposes his own in the following terins :
• 1. During inspiration and expiration, the blood finds . an easy passage through the vessels of the lungs, as by their alternate inflation and contraction, it is prefied forward to the left ventricle of the heart. After inspiration is
completed, it begins to flow with more difficulty; and at the end of expiration (if inspiration does not foon succeed) its motion is still less free. After expiration, therefore, the blood, on account of its difficult passage through the pulmonary vessels, is partly accumulated in them, and by distracting their sensible fibres and membranes, acts as a jlimulus upon the pulmonic nerves, occasioning an uneasy fence of fulness, itoppage, or suffocation in the breast, which is more or less remarkable, according to the time during which respiration is stopt, the capacity of the pulmonary vessels, 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 intercostal muscles should be brought into contractions by a stimulus acting upon
the lungs, than that a stimulus should alternately contract the heart and alimentary tube, we may afsure ourselves of the certainty of the fact, from the strongest and justest analo
Thus, says he, for example, if a few drops of water, or any other liquor, by an accident in swallowing, fall into the trachea, the diaphragm and intercostal muscles are instantly called into action, and continue to be agitated with alternate contractions and relaxations, till the stimulating cause is removed. Again, if a thin pituit secerned in too great quantity, by the vessels and glands of the bronchia, distils upon the vesicles of the lungs, alternate convulsions of the diaphragm, intercostal and abdominal muscles, ensue; which are repeated over and over again, till the irritating cause is lefiened or expelled.-- In a true peripneumony aiso, when, by reason of an obstruction in the pulmonary arteries, the blood passes through the lungs with great difficulty, a short cough is almost a conftant symptom. is it not therefore reasonable to infer, that a less remarkable flimulus, or an easy sensation in the vessels of the lungs, will be followed by gentler contractions of the inspiratory inuscles?
• After expiration is finished, the blood beginning to be accumulated in the lungs, will, not only by its quantity distracling their veifels, but also by its heat, occasion an uneasy sensation, that is, act upon those parts as a stimulus; in consequence of which the diaphragm and intercoftal muscles are contracted, and inspiration is performed; by which the blood being not only cooled by the external air, but its passage also promoted towards the left ventricle of the heart, the stimulus or uneafy sensation ceases: hence