90. An oyfter, being put into a very fmall receiver, and kept there long PNEUMATICS. enough to have, fucceffively, kill'd three or four birds, or beafts, &c. was shell-fish in an not thereby kill'd, nor, for ought we could perceive, confiderably di- exhausted refturb'd; only at each fuck we perceiv'd, that the air, contain'd betweenceiver. the two fhells, broke out at their commiffure; as we concluded from the foam which, at thofe times, came out all around that commiffure. About twenty-four hours after, I found, that both this oyfter, and another, that had been put, at the fame time, into the receiver, were alive.

On the fame day we put a pretty large craw-fifh into a large receiver, and found, that tho' he had been before injur'd by a fall, yet he feem'd not to be much incommoded, by being included, till the air was, in great meafure, pump'd out; and then his former motion prefently ceas'd, and he lay as dead, till, upon letting in a little air, he foon began to move afresh; and, upon withdrawing the air again, he prefently, as before, became movelefs. Having repeated the experiment two or three times, we took him out of the receiver, when he appear'd not to have fuffer'd any harm.

91. Having put an oyfter into a vial, full of water, before we included it in the receiver, that thro' the liquor the motion of the bubbles, expected from the fish, might be the better feen, and confider'd; this oyfter prov'd fo ftrong, as to keep itfelf clofe fhut, and reprefs'd the eruption of the bubbles, that, in the other, forc'd open the fhells, from time to time; and kept in its own air, as long as we had occafion to continue the trial.

92. A craw-fish, that was thought more vigorous, being fubftituted in the place of the former craw-fifh, tho' once he feem'd to lofe his motion. together with the air; yet, afterwards, he continu'd moving in the receiver, in fpight of our pumping.

93. We took a receiver, fhaped almoft like a bolt-head, containing near A feale-fifh in an exhausted a pint; and the globular part of it, being almost half full of water, we receiver. put into it, at the orifice, a fmall gudgeon, about three inches long; which, when it was in the water, fwam nimbly up and down therein : then, having drawn out the air, fo that about nineteen parts of twenty, or more, were exhausted; we fecur'd the return of the air from injuring our experiment.

Now the neck of the glafs, being very long, tho' there appear'd numerous bubbles all about the fifh; yet the reft of the water, notwithftanding the withdrawing of fo much air, emitted no froth, and but few bubbles.

The fifh, both at his mouth and gills, for a long time, discharg'd fuch a quantity of bubbles, as appear'd ftrange; and for about half an hour, when ever he refted a while, new bubbles would adhere to many parts of his body, (as if they were generated there) efpecially about the fins and tail; fo that he would appear almoft befet with bubbles: and if, being excited to fwim, he was made to fhake them off, he would quickly, upon a little reft, be befet with new ones, as before..

Almoft

PNEUMATICS,

Two animals, with large wounds in their

abdomen, inpneumatical

cluded in the

receiver.

Almost all the while, he would gape, and move his gills, as before he was included; tho', towards the end of the time, I watch'd him, he often neither took in, nor emitted any aerial particles that I could perceive.

After a while, he lay almoft conftantly with his belly upwards; and, yet, would, in that posture, fwim briskly, as before. Nay, foon after, he feem'd to be more lively than at firft putting in.

In about an hour and a half after he had been feal'd up, I found him almost free from bubbles, with his belly upwards, and feeming fomewhat tumid, yet lively as before. But, an hour and a quarter after that, he feem'd to be movelefs, and fomewhat ftiff; yet, upon fhaking the glafs, obferving faint figns of life in him, by fome languid motions he attempted to make, when excited; I open'd the receiever, under water, to try if that liquor, and air, would recover him; when, the external water rufhing in, till it had fill'd the vacant part of the ball, and the greatest part of the ftem, the fifh funk to the bottom of it, with a greater appearance than ever of being alive in which ftate, after he had continu'd a pretty while, I, by the help of the water he fwam in, got him thro' the pipe, into a bafon of water, where he gave more manifeft figns of life. But, yet, for fome hours, he lay on one fide or other, without being able to fwim, or reft on his belly, which appear'd very much fhrunk in.

All the while he continu'd in the bafon of water, tho' he mov'd his gills, as before he had been feal'd up; yet I could not perceive, that he did, even in his new water, emit, as formerly, any bubbles; tho', two or three times, I held him by the tail in the air, and put him into the water again; where, at length, he grew able to lie conftantly upon his belly; tho' that retain'd much of its former lanknefs. And he lived, in the bafon, eight or ten days longer; tho' feveral gudgeons, fince taken, died there, in a much less time.

94. Sept. 12. A fmall bird, having the abdomen open'd almoft from flank to flank, without injuring the guts, was put into a little receiver, and the pump being fet a-work, continued, for fome little time, without giving any figns of diftrefs; but at the end of about a minute and an half from the beginning, fhe began to have convulfive motions in the wings; and, tho' the convulfions were not univerfal, or appeared violent, as is ufual in other birds when the air is withdrawn, yet, at the end of two full minutes, letting in the air, and then taking off the receiver, we found the bird irrecoverable, tho' there appear'd no notable alteration in the lungs; and the heart, or, at leaft, the auricles of it, continued beating for a while after,

95. We took, alfo, on the fame day, a pretty large frog, and having, without violating the lungs, or the guts, made two fuch incifions in the abdomen, that the two curl'd bladders, or lobes of the lungs, came out, almoft totally, at them; we fufpended the frog, by the legs, in a small receiver, and, after we had pump'd out a large part of the air, the animal ftruggled very much, and feem'd to be much diforder'd; and, when the receiver was well exhaufted, fhe lay ftill, for a while, as if fhe had been

dead;

dead; the abdomen and thigh being very much fwell'd, as if fome rarify'd PNEUMATICS air, or vapour, forcibly diftended them. But as, when the frog was put in, one of the lobes was almoft full, and the other almoft fhrunk up; fo they continu'd to appear, after the receiver had been exhausted: but, upon letting in the air, not only the body ceas'd to be tumid, but the plump bladder appear'd, for a while, fhrunk up as the other; and the receiver being remov'd, the frog prefently revived, and quickly began to fill the lobe again with air.

heart of a cold

ceiver.

96. The heart of an eel being taken out, and laid upon a plate of tin, The motion of in a small receiver; when we perceiv'd it to beat' there, as it had done the separated in the open air, we exhaufted the veffel, and faw, that tho' the heart animal in the grew very tumid, and, here and there, fent out little bubbles, yet it exhausted recontinued to beat as manifeftly as before, and feemed to do fo more fwiftly; as we tried by counting the pulfations it made in a minute, whilft it was in the exhaufted receiver, and when we had re-admitted the air, and alfo, when we took it out of the glafs, and fuffer'd it to continue its motion in the open air. The heart of another eel, being, likewife, taken out, continued to beat in the empty'd receiver, as the other had done.

97. The heart of another eel, after having been included in an exhausted. receiver, and then accurately fecured from leaking, tho' it appear'd very tumid, continu'd to beat there an hour; after which, finding its motion very languid, and almoft ceas'd; by breathing a little upon that part of the glafs where the heart was, it quickly regain'd motion, which I obferv'd a while; and, an hour after, finding it almoft quite gone, I was able to renew it, by the application of a little more warmth. At the end of the third hour, a bubble, that appear'd to be placed between the auricle and the heart, feem'd to have, now and then, a little trembling motion; but it was fo faint, that I could no more, by warmth, excite it, fo as plainly to perceive the heart to move: wherefore, I fuffer'd the outward air to rush in, but could not difcern, that, thereby, the heart regain'd any fen-fible motion, tho' affifted with the warmth of my breath and hands.

98. Sept. 10. A green-finch, having his legs and wings tied to a weight, The times where was gently let down into a glafs body fill'd with water; the time of his in animals may be kill'd by total immersion being mark'd. At the end of half a minute after that time, drowning, or the ftrugglings of the bird feeming finish'd, when being fuddenly drawn up the air, compa withdrawing of again, he was found quite dead.

A fparrow, very lufty and quarrelfome, was tied to the fame weight, and let down after the fame manner; but tho' he feem'd to be more vigorous under water than the other bird, and continued ftruggling almoft to the end of half a minute, from the time of his total immerfion (during which, there afcended, from time to time, large bubbles from his mouth) yet, being drawn up as foon as ever the half minute was compleated, we found him, to our wonder, irrecoverably gone.

99. A small moufe, being held under water by the tail, emitted, from time to time, feveral aerial bubbles out of his mouth; and, at laft, as a spectator affirm'd, at one of his eyes: being taken out, at the end of half a mi

nute

red.

PNEUMATICS nute, and a few feconds, he yet retain'd fome motions: but they prov'd only convulfive ones, which, at laft, ended in death.

100. We fo tied a confiderable weight of lead to the body of a duck, as not to hinder her refpiration, yet keep her under water; which we had found a fmall weight unable to do, by reafon of her ftrength; and even a great one, if ty'd only to her feet, in fuch a middle-fized veffel as ours was; because of the height of her neck and beak. With this clog, the duck was put into a tub full of clear water, under the furface whereof, fhe continued quietly for about a minute; but afterwards began to be much difturb'd: the fit being over, and perceiving no motion in her, at the end of the fecond minute, we took her out of the water; and, finding her in a good condition, after we had allow'd her fome breathing-time, to recruit herfelf with fresh air, we let her down again into the tub, which, in the mean time, had been fill'd with fresh-water; left the other, which had been troubled with the fteams and foulnefs of the body of the animal, might either haften her death, or hinder our perceiving what should happen.

The bird being thus under water, after a while, began, and, from time to time, continued to emit bubbles at her beak. There, alfo, came out at her noftrils several real bubbles, from time to time; and when the animal had continued about two minutes under water, fhe began to ftruggle very much, and to endeavour either to emerge, or change pofture; the latter of which, fhe had libetty to do, but not the former. After four minutes, the bubbles came much more fparingly from her: then, alfo, fhe began to gape, from time to time; which we had not obferv'd her to do before, but without emitting bubbles; and fo fhe continued gaping till near the end of the fixth minute; at which time all her motions, fome whereof were judg'd convulfive, and others that had been excited by rouzing her, appear'd to ceafe, and her head to hang carelefly down, as if fhe were quite dead. Notwithstanding which, we, for greater fecurity, continued her under water a full minute longer; and then, finding no figns of life, we took her out; when, being hung by the heels, and gently prefs'd in convenient places, fhe was made to void a confiderable quantity of water : but whether any of it had been received into the lungs themfelves, we wanted time and opportunity to examine. All the means we used to recover the bird, proving ineffectual, we concluded, the had been dead a full minute before we removed her out of the water: fo that, even this waterfowl, was not able to live in cold water, without taking in fresh air, above fix minutes.

101. A duckling, having a competent weight ty'd to her legs, was let down into a tub of water, which reached not above an inch or two above her beak: during the most part of her continuance wherein, there came out numerous bubbles at her noftrils; but there feem'd to proceed more and greater, from a certain place in her head, almoft equi-diftant from her eyes, tho' fomewhat lefs remote from her neck than they. Whilft fhe was kept in this condition, fhe feem'd, frequently, to endeavour at diving lower under water; and, after much struggling, and frequent gaping, fhe had, fe

veral convulfive motions, and then let her head fall down backward, with PNEUMATICS. her throat upwards. To this movelefs pofture fhe was reduced at the end of the third minute, if not fooner; but, a while after, there appear'd a manifeft tremulous motion in the two parts of her bill; which continued for fome time, and was, perhaps, convulfive: but this alfo, ceafing, at the end of the fourth minute, the bird was taken out, and found irrecoverable.

102. A viper, that we kept in an exhaufted receiver, till concluded to have been quite dead, was, nevertheless, not thrown away, till I had try'd what could be done, by keeping her all night in a glass-body, and a warm digestive furnace: upon which, this viper was found, the next morning, not only reviv'd, but very lively.

We, therefore, put her into a tall glafs-body of water, fitted with a cork to its orifice, and deprefs'd it with a weight, fo that fhe could have no air. In this cafe,we obferv'd her, from time to time; and, after she had been duck'd a while, the lay, with very little motion, for a confiderable time. After an hour and a quarter, the often put out her black tongue: at the end of near four hours, the appear'd lively; and, as I remember, about that time, alfo, put out her tongue; fwimming, all this while, as far as we obferv'd, above the bottom of the water. At the end of about seven hours, or more, The feem'd to have fome life; her pofture being manifeftly chang'd in the glafs, from what it was a while before. Not long after, fhe appear'd quite dead; her head and tail hanging down movelefs, and directed towards the bottom of the veffel; whilft the middle of her body floated as much as the cork would permit it.

confiderable de

tion.

103. In the generality of our pneumatical experiments upon animals, it Animals in air fuited with our purpose, to rarify the air as much, and as fuddenly as we brought to a could; but I had other trials in view, wherein an extraordinary degree of gree of rarifa. rarifaction, yet not near the highest to which the air might be brought by our engine, feem'd likelieft to conduce; as particularly to afford fome light in the nature of those diseases, that are thought, primarily, to affect refpiration, or its organs.

Wherefore, having gages, by help of which fuch experiments might be much the better perform'd, I attempted several of them in the following

manner.

Aug. 16. A linet being put into a receiver, able to hold about 4 pints and a half of water, the glafs was well clos'd with cement and a cover; but none of the air drawn out with the engine, or otherwife. And tho' no new air was let in, nor any change made in the imprifon'd air, yet the bird continued there three hours, without any apparent approach to death and tho' fhe feem'd fomewhat fick, yet being afterwards taken out, fhe recover'd, and liv'd several hours.

104. Aug. 18. From the receiver above-mention'd, we drew about half the air, whilft a linet was in the glafs; and in that rarified air (which appear'd by a gage to continue in the fame ftate) the bird liv'd an hour and near a quarter before fhe feem'd in danger of death: after which, the air being let in, withVOL. II. Zzz

out