was born. They must conceive, that the infant who is born with a large discolouration on any part of its skin, had, before the discolouration took place, a fair skin: that the child who is born with six toes, had originally but five; and again that the child who is born with one leg, or one arm, had ori ginally two; and so of every other preternatural appearance, whether it be an increase or defect of the parts of the body.

Now, Madam, to shorten my letter as much as possible, I shall single out a case, from the many narratives publish ed in favour of that opinion; and, by exposing the absurdity of this one example, you will infer, that all the other wonderful stories of the same kind, are equally absurd. It has been alleged, that a lady advanced five or six months in her pregnancy, has been so terrified by a beggar's thrusting suddenly the stump of an amputated arm into her coach, that the child, of which she was afterwards brought to bed, was born with a stump of an arm, resembling that of the beggar.

Be so good to pause here, awhile, and consider what an operation must be performed to work this effect. A child at the term of five or six months, is of a considerable bulk, and the arm itself not small. This arm must drop off by the power of imagination; there must be no blood lost to endanger the life of the child, and the wound must be healed before the birth. Does not the mere stating this proposition expose its ridiculousness? I am almost ashamed to urge any other reasons to demonstrate the folly of it; but shall observe, for argument's sake, that, admitting a limb could drop off by the force of fancy, it still would remain with the mother, till the delivery; the bones, at least, would not putrify and waste away, though the flesh should: but it was never pretended, in cases of this nature, that any part of the limb was found by the midwife; and, what is also worthy of observing, the stumps of all such imperfect limbs have a smooth skin, which plainly evinces they were, from their first formation, of the same figure; for, had there been a wound, there would have been a scar, and scars are very distinguishable from sound skin.

Perhaps you will reply, that, in the instance I hav› quoted, they committed a mistake who ascribed such an event to such a cause; but that, probably, though the power of imagination cannot work on the large limbs such great effects, still it may on the lesser. In answer to thi› suppo sition, I must inform you, that the histories of this kind stand upon the same foundation, and are equally wel attested with any of the others, which may appear less marvellous;

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and if the evidence of the one be given up, the evidence for the rest will fall to the ground. Besides, Madam, a philosopher will instruct you, that what seems in your eyes little and simple, is as wonderful, in its organization, as things of a larger scale; that to add a sixth finger, or a sixth toe, to a child, is as great an instance of a miraculous power, as to add two or three legs, or two or three arms: therefore you may be assured, all the metamorphoses said to be wrought during pregnancy, are equally practicable, and equally true.

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I believe there is no defect more frequent than that of the hare lip, and it seldom happens that a woman who has a child with that deformity, does not endeavour to recollect she either longed for hare, or was frightened by a hare, or saw somebody with a hare lip, no matter which. A woman, already prepossessed there must have been some such cause, is not long at a loss; her memory, or her prejudice, soon furnishes her with a fact, and the instance of this child is added to the long catalogue of forgeries and false facts.

Discolourations, or spots on the skin, another very common appearance, are fondly resembled, by some people, to certain fruits. I do not mean to enter particularly into the consideration of this article; and should not have mentioned it, but to expose the great propensity there is in the world, to uphold one piece of superstition by another. You must have heard, how much it is believed, that these spots grow vivid, as the respective fruits they are said to resemble, ripen; and afterwards fade away during the winter season: now, though the assertion be false, and the falshood very palpable, yet eredulity has hitherto prevailed over truth, at least amongst the vulgar.

The preternatural configuration of the parts of the body, is a much more frequent phenomenon than the generality of mankind imagine: the deviations on the external parts only, are the objects of their contemplation; but anatomists know, that the internal parts are likewise subject to the same disorders. To take one example out of a hundred it has been observed, in the dissection of a body, that, instead of two kidneys, nature has only bestowed one, which she has enlarged, and placed upon the middle of the back-bone. In this instance, where the variation was imperceptible, till the death of the subject, I will be bold to say, that the mother never suggested any frights or longings as the cause of that effect; and yet, the case was as extraordinary as where that plea is advanced. Again, it happens that these preternatural productions occur equally amongst all rauks of people, and in every part of the world, as much amongst

those who have never pretended to assign a cause, as amongst the credulous, who never want one. If then we

grant it to be sometimes an event of nature, why should we doubt that it is not always so? Do we not smile, when Sir Roger de Coverly seriously says, in the Spectator, that he does not believe Moll White had any hand in the high wind, which blew down one end of his barn? Storms, we know, are events that must and do arise in the ordinary course of nature; and therefore we laugh when weak people suppose they are sometimes raised by witches and conjurers.Give me leave to say, that it is equally unphilosophical to admit, that irregularities in the formation of a child, are sometimes events in the ordinary course of nature, and at other times are brought about by a cause so very disproportionate to the effect: I may justly say disproportionate, since a knife and a saw, or a hammer and chisel, seem requisite for the operation, in some of the instances I have alluded to.

I have before hinted, that not only in the animal, but also in the vegetable world, there is a variety of preternatural productions; which circumstance alone should teach us, that whatever be the appearance, that appearance took its rise in the very moment of its formation; since it cannot be presumed, that plants are actuated by any perception or fancy, as women are said to be: but lest you should tell me, this is an unfair parallel, and that you do not understand the analogy betwixt vegetables and animals, I shall beg leave to illustrate what I have laid down by another consideration.

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Those who have been attentive to their poultry," will inform you, that chickens are as liable to a preternatural structure of their organs, as children this proposition being granted, let us proceed a little farther into the inquiry.The egg, in order to be hatched, is placed under the hen, the heat of whose body gives motion to the fluids which nourish the chick, till it becomes sufficiently strong to break the shell, when it is produced with a claw extraordinary, or any other preternatural appearance, to which chickens are liable. Now, in this case, the extraordinary claw, if we take this instance for our argument, must either have been formed in the moment of conception, or been added at some period afterwards, when we suppose the hen to have been under the influence of some powerful imagination. Which supposition then do you admit? if you grant that the chick was originally framed in this shape, it follows, from the rules of analogy, that all preternatural births have the same cause:

if it was not, the fancy of the hen must have operated through the shell to work the effect. I flatter myself, however, that prone as we are to delight and believe in the marvellous, this is too marvellous and absurd a notion to gain much credit from a woman of your good sense. But, Madam, an anatomist will tell you, that, considering the nature of the communication betwixt the mother and the embryo, it seems equally incomprehensible to him, that an embryo should receive an impression from the fancy of the mother, through such a labyrinth of vessels, as that a chick should, through the pores of the egg-shell.

If after what I have here said upon the subject of the hen and the egg, you have still a secret persuasion, that the hen may (in some wonderful manner, you do not know how) whilst she is sitting, affect the chick in the egg, so as to alter its frame, know, for a certainty, that eggs hatched in dunghills, stoves, and ovens, produce as many monstrous births, as those which are hatched by hens; which I should imagine, proves irrefragably, that the chick is produced in the very shape in which it was formed.

I hope, from the light in which I have placed this popular piece of superstition, you are now convinced it has not the least foundation in truth. It is not more than a century since some men of learning gave credit to the efficacy of sympa thetic medicines; they believed that sympathetic medicines, like other charms, communicated their virtues to patients at a distance. Learning, and good sense, have at length utterly banished this visionary conceit; and I do not doubt but, in another century, the prejudice I have been here combating, will meet with the same contempt. Men of letters do even now embrace the doctrine I inculcate; and it is to be hoped, that, in a short time, it will be the opinion of the common people. 1764, Oct.

I am, Madam, &c.

IV. Solution of Optical Phenomena. Part of a Letter from the late James Logan, of Philadelphia, to the late Sir Hans Sloane. From an original MS. communicated by Peter Collinson, Esq. IT may perhaps be needless now to add any thing in confirm'ation of Doctor Wallis's solution of the sun and moon appearing so much larger at rising and setting, than in a greater altitude; though some have gone on very absurdly, and still go on to account for it from vapours; which I remember was given me in my youth for the true cause of it,

It is true, indeed, that it is these vapours in the atmosphere alone, that make those bodies, when very near to the horizon, appear in a spheriodical form, by refracting,. and thereby raising (to sight) the lower limb more than the upper, yet these can be no cause of the other. Sun or moon, each subtending about half a degree, appears in the meridian of the breadth of eight or ten inches, to some eyes more, and to others less, and in the horizon to be two or three feet, more or less, according to the extent of ground they are seen over.

But if one has an opportunity, as I have here frequently had, of seeing the sun rise or set over a small eminence at the distance of a mile or two, with tall trees standing on it pretty close, as is usual in woods, without underwood, his body will then appear to be ten or twelve feet in breadth, according to the distance and circumstances of the trees he is seen through, and where there has been some thin underwood, or a few saplings, I have observed that the sun setting red, has appeared through them like a large extensive flame, as if some house was on fire beyond them.

Now the reason of this is obvious, viz. that being well acquainted with trees, the ideas of the space they take up are in a manner fixed, and as one of those trees, subtends an angle at the eye, perhaps not exceeding two or three seconds, and would scarcely be distinguishable, were it not for the strong light behind them, the sun's diameter of above thirty inches, takes in several of them, and therefore will naturally be judged vastly larger. Hence it is evident, that those bodies appear greater or less, according to the objects interposed, or taken in by the eye on viewing them, and to this only is this phenomenon to be imputed.

J. LOGAN.

Part of a second Letter from James Logan, to Sir Hans Sloane.

I OBSERVED the ingenious gentleman Stephen Hales, in his Vegetable Statics, to mention that phenomenon of the streaks or darts of lightning in thunder storms appearing crooked and angular (I do not remember his words) as a thing unaccounted for, and therefore guessed at a solution of it; but if I mistake not, I sometime since discovered the true one, which was this-Having a sash window, glazed with bad or waved glass, and sitting about twelve feet distance from it, one of my people was carrying by that window, at some distance from it, a long lath on his shoulder, which, through that glass, appeared to my view exactly in the form D d

VOL. II.

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