large drops; which would make the instrument less accurate. For the thermometer's beginning to rise immediately after a drop is fallen, or just as it is going to fall (in which case it will return back into the tube,) will make a difference of such part of a degree nearly as that drop answers to. To prevent this incon venience, the top of the shorter leg close to the ball is contracted, by being held in the flame of a lamp; and the passage is further straitened by a solid thread of glass placed within the tube, and extending from the bottom of the shorter leg to the part near the ball A, where it is most contracted. By this means, as soon as any small portion of mercury is got beyond the end of the thread of glass, it breaks off and falls into the ball in very small drops. This thread of glass is fastened by the heat given to the tube in making the bend next to the ball. In order to fill the shorter leg with mercury, to fit the instrument for a new experiment, it must be inclined till the mercury in the ball covers the orifice of the tube n. The cylinder being then heated, the mercury will be forced into the shorter leg, and will run down the thread of glass in drops, which will soon unite. By this means such a quantity of mercury must be got into the shorter leg, as on the cooling of the instrument, will be sufficient to drive all the spirit of wine into the ball with a less degree of cold than what the thermometer is likely to be exposed to. The scale of degrees on the shorter leg will, in different seasons, be liable to an error of the same kind as that which was explained in the first-mentioned thermometer; but in this it will be less considerable, as the space between the two scales is filled with mercury, whose expansion is about 6 times less than that of spirit of wine.

The thermometer for finding the greatest cold, if applied to the purpose of immerging it deep in the sea to find its temperature, must be left open. at top, for fear of breaking by the pressure. There is another inconvenience to be avoided; which is, that the mercury in the ball a, by the tossing of the instrument, might sometimes get into the shorter leg of the syphon, which would spoil the experiment. To prevent such an accident, the most convenient construction which occurred, was that of fig. 4, which differs from fig. 3, in having the ball A omitted; so that the mercury running out of the shorter leg will fall to the bottom of the cylinder, and will not be so liable to get back into the tube by motion. The cylinder is made to stand not quite parallel to the legs of the syphon, that the contained mercury may more easily be brought to touch the end of the tube, in order to fit the instrument for a new experiment. If by means of a bladder the sea-water can be kept out of the glass, this instrument may be made to show the common degrees of heat. If ther mometers of this kind were to be sent up into the air by means of a kite, they might be made like those proposed for the sea; but it would not be necessary to leave them open.

XXXIX. On a Double Female Monster which was born at Szony in Hungary, Oct. 26th 1701, and which died Feb. 23d 1723, at Presburgh, in the Convent of the Nuns of St. Ursula, and was buried there. By Justus Johannes Torkos, M. D., F. R. S. p. 311. From the Latin.

1. Dr. T. premises his account of this monstrosity by observing, that it affords a remarkable instance of the power of the mother's imagination on the fœtus in utero. For at the beginning of her pregnancy, the mother attentius contemplabatur canes coëuntes, arctius cohærentes, et capitibus erga se invicem quodammodo conversos, eosque sibi crebrius præfigurabat.'

:

2. At the time of parturition, the body of Helen was first excluded as far as the navel; three hours after the feet were delivered, together with the body of Judith, joined to that of Helen. Of the two, Helen was the tallest and straightest. Notwithstanding they were joined together at the back below the loins, yet they were turned with their faces and bodies half sideways (semilateraliter) towards each other, so that they could sit down, and move backwards and forwards. One anus, situated between the right femur of Helen and the left femur of Judith, was common to both. Unam quoque habebant vulvam, intra 4 pedes reconditam, ut dum erectis starent corporibus, ne vestigium ejus conspicuum esset.' It was observed that when one of them wanted to go to stool, the other felt a similar desire; but that in regard to the urinary evacuation, when one of them felt an inclination to make water the other did not.* Hence in their youth, though in other respects they were exceedingly fond of each other, there frequently arose violent contentions between them, in which one would carry the other on her back, or drag her along to the place to which she wanted to go.

3. In the 6th year of her age, Judith was affected with a palsy of the left side, the consequence of which was, that, although she recovered, she ever afterwards remained weaker, more sluggish and dull; on the contrary Helen became more active, more lively, and more beautiful.

4. Not only was there this difference in their persons, but a difference was also observable in regard to their vital, animal, and natural functions, in health as well as in disease. And although they had the small pox and measles at one and the same time; yet they had other disorders separately. Judith was often convulsed, while Helen remained free from indisposition. Helen had a pleuritic affection. Judith had a fever. One of them had a catarrh and a colic, while the other continued well.

5. At the age of 16 the menstrua appeared and continued, but not at equal

* Another account, noticed further on, states that the alvine, as well as the urinary evacuation, was performed by each at different times.

times or in the same manner, or in the same quantity. Sometimes one, sometimes the other, would be most disordered at such periods; but Judith was more frequently convulsed, and was subject to various hysterical and pectoral af

fections.

6. On the 8th of Feb. 1723, in the 22d year of their age, Judith was seized with violent convulsions, succeeded by coma, which terminated fatally on the morning of the 23d of February. During this time Helen was affected with fever, accompanied with frequent faintings, by which she was so much debilitated, that although she was still sensible and could speak, she fell into an agony three minutes before Judith; after a short struggle, they both expired almost at the same instant.

7. On opening their bodies, each was found to be provided with distinct viscera; which were all in a healthy condition in Helen; but the heart of Judith was preternaturally enlarged and inclosed in a very strong pericardium; the right lobe of the lungs was in a putrid state. The descending aorta and descending vena cava, before they send off the iliac arteries and iliac veins, were found coalesced together. All the viscera in the abdomen were in a sound state. Each of the 2 bodies had its own liver, its own spleen, its own pancreas, its own kid-, neys, its own bladder, its own uterus, with the ovaria and Fallopian tubes, and separate portions of vagina, terminating in one common vagina. Partes genitalium externorum, præter commune orificium vaginæ, cuilibet erant propriæ velut clitoris, nymphæ, orificium urethræ; alæ seu labia utrinque ad perinæum concurrentia fossulam navicularem densiorem constituerant.' The stomach and intestines were situated in the natural manner, in both; but the 2 intestina recta were united into one at the os sacrum, so as to form a sufficiently large. and common canal. The os sacrum was concreted together at the 2d division, and forming one body, terminated in one os sacrum and one os coccygis, common: to both.

Dated Presburgh, July 3d, 1757.

The interval between the reading of this paper before the R. S. and its publication, was occasioned by the long indisposition, and afterwards death, of their President Martin Folkes, Esq. who having taken it to his house with a view of collecting and adding to it some further particulars, it could not be found after his decease. But Dr. Torkos, the writer, being again applied to, immediately transmitted the copy of it printed above: and, in order to supply in some measure the want of what Mr. Folkes's extensive reading and industry might have furnished the public with, in relation to so very remarkable a fact, the following accounts, printed and manuscript, are subjoined as a supplement to the preceding article.

Extract of a Letter from William Burnet, Esq. F. R. S. eldest Son of Dr. Gilbert Burnet, Lord Bishop of Salisbury, to Doctor Hans Sloane, dated Leyden, May 9, 1708, N. S.*

In this letter Mr. Burnet states that he had seen, and attentively examined this union of twin sisters at the Hague. They were Hungarians: the urinary passage was between the 2 foremost thighs. The situation of this, as well as of the anus, was the same to outward appearance as naturally, with this difference, that they were between 2 different bodies here, whereas in the course of nature they are between the 2 parts of the same body. It seems probable that their parts were distinct; but that the most remote labia of each were outwardly visible, and the 2 contiguous ones within. There seemed to be no cheat in the thing; and the skin where they were joined was perfectly smooth, without any scar. They were then about 6 years old. They spoke French and High German. They were very full of action, and talked one more than the other. When one stooped to take up any thing, she carried the other quite from the ground; and that one of them often did, being stronger as well as more lively than the other. They had not their feeling common any where but in the place of their conjunction.

This letter was read to the R. s. on the 12th of May 1708.

Soon after the date of Mr. Burnet's letter, the twin sisters were brought to England and publicly shown in London, as appears from the following мs. note in a copy of the print bound up by the writer with Fortunius Licetus de Monstris,|| edit. Amstelod, 1665, 4to. in the possession of T. Wilbraham, M. D. “Londini 14 Junii 1708, has vidi gemellas (plus annis 6 natas) quarum forma et vivacitas elegantior et vegetior quam pictura et descriptio."

F.R.S.

Another account of them by an eye-witness in London is in a Ms. vol. among those of Sir Hans Sloane, Bart. in the British Museum, intitled, a short History of human Prodigies and monstrous Births, of Dwarfs, Sleepers, Giants, strong Men, Hermaphrodites, numerous Births, and extreme old Age, &c. The name of the writer was James Paris du Plessis. In p. 39, under the title Two Sisters conjoined, he gives a drawing of them, and the following description: "These 2 monstrous girls were born at Szony in Hungary in the year 1701. They were born conjoined together at the small of the back. I asked the father and mother, if they could not be separated one from the other? but they answered, no;

* Original letters to Sir Hans Sloane, Bart. vol. A-B. in the British Museum.-Orig.

+ This letter was accompanied with a print of these conjoined twin sisters. Journal, vol. xi. p. 143.-Orig.

In this treatise,!L. 2. p. 80. is the following passage: in pago Rorbachio non procul Heydelbergâ, Paræi etiam relatu, gemini utriusque sexûs obversis tergoribus annexis orti sunt.-Orig.

because the urinary and fœcal vessels and passages were so united, as to have but one issue for the urine, and another for the excrements, betwixt both. They were brisk, merry, and well-bred; they could read, write, and sing very prettily: they could speak 3 different languages, as Hungarian, High Dutch, [German] and French, and were learning English. They were very handsome,

very

well shaped in all parts, with beautiful faces. Helen was born 3 hours before her sister Judith. When one stooped, she lifted the other from the ground, and carried the other upon her back; neither could they walk side by side. They loved one another very tenderly. Their clothes were fine and neat. They had 2 bodies, 4 sleeves, and 1 petticoat served both bodies, and their shifts the same. When one went forward, the other was forced to go backward."

A later and more particular account is contained in p. 41, & seqq. of a book very seldoin met with in this country, being printed at Vienna in 1729, intituled, Gerardi Cornelii Drieschii Historia magnæ Legationis Cæsareæ, quam Caroli VI. auspiciis suscepit Damianus Hugo Virmondtius, &c. The account given in this book coincides in most respects with the preceding accounts. This author however, states that neither the alvine nor the urinary evacuations were always performed at the same time by both sisters; that the menstrua happened at different times, one having them a week or more after the other; that when one was asleep the other was often awake; that one had a desire for food, when the other had not, &c. That between the 2 sisters there was a striking difference, not only as to bodily strength and activity, but also in regard to intellectual powers; that Helen was of very engaging manners, and excited much interest by showing that she was sensible of her own unfortunate situation and that of her sister; that although they both tenderly loved and often kissed each other, yet in their early youth they not unfrequently quarrelled and fought in consequence of their desires for the alvine and urinary evacuation coming on at different times; that during their travels, they had learned various foreign languages, some of which they had forgotten, but that at the time this account was written, they could still speak German, French, and Hungarian; that after they were placed in the convent at Presburgh, they were taught to read and write, instructed in religion, and employed in needle work, the manufacture of lace, &c.

XL. Observations on the Origin and Use of the Lymphatic Vessels of Animals : being an Extract from the Gulstonian Lectures, read before the Coll. of Physicians of London, By Mark Akenside,* M. D. Fell. of the Coll. of Phy sicians, and F. R. S. p. 322.

It is proved, by a multitude of experiments, that the lymphatics communicate with the blood-vessels. They may be distended by blowing air, or by injecting. water or mercury, into an artery; and the lymph, which they carry, is frequently

*This ingenious poet and physician was a native of Newcastle upon Tyne, where he was born in 1721, and where he received his grammatical education. His father, who was a butcher of the U

VOL. XI.