Page images

LXXXVII. An Account of Mr. Mason's Paper concerning the Going of Mr. Ellicott's Clock, at St. Helena. By James Short, M.A., F. R. S. p. 540. In this paper Mr. Mason tells us that, in order to determine the regularity of the motion of Mr. Ellicott's clock, ne resolved to make observations of the occultations of stars, by a ridge of rocks, the altitude of which was about 30° above the place of observation, and at about a quarter of a mile distance; but that this method was soon improved by the Rev. Mr. Maskelyne, who proposed to make use of the equal altitude instrument for that purpose, by observing the vanishing of the stars out of the field of the telescope. By observations of this sort, from the 31st of October to the 19th of November 1761, he found that the clock went very regularly, not varying so much as a second in that time; but from the 19th of November to the 3d of December, he found that the clock had gone slow, or lost 2 seconds of time; and this alteration he imputes to the wedges, behind the clock, having got loose, shrunk as he supposes by the dryness of the place; he therefore secured the wedges, and found that from the 3d of December to the 22d of December, the clock did not vary in its motion above one second of time. On the 5th of January the clock was stopped; and it appears that the clock did not vary so much as one second of time from the 9th of January to the 22d of January. The thermometer was hung by the side of the clock, and he never saw it higher than 74 divisions, nor lower than 67, from the 12th of Jan. 1761 to the 18th of January 1762. He has given no description of the clock.

Remark. The method proposed by Mr. Mason, of making these observations by means of the occultations of stars behind the ridge of rocks, was certainly better than the other, by means of the equal altitude instrument; for it has been found by experience, that any instrument, however securely fixed, is liable to alterations in its direction, owing perhaps to the effects of heat and cold, moisture and dryness, in the parts to which the instrument is fastened; and an equal altitude instrument was the most improper for this purpose, because it could not be rectified by looking at a distant mark, to correct any alterations it might have suffered in its position or direction. Mr. Mason further says, that by comparing the observations of the going of the clock, made at St. Helena, with those made at the Cape of Good Hope, the difference of the effect of gravity at the two places may be found.

Remark. No observations of the difference in the going of a clock, made at different places, can with certainty determine the difference of the effect of gravity at these places; because it has been found by experience that the same clock, placed at different times on different walls, in the same room, will make a difference in the going of the clock, even though every part of the clock remains the same.

LXXXVIII. The Eclipse of the Moon, May 8, 1762, in the Morning, observed by Mr. Short, in Surry-street, London. p. 542.

Diameter of the moon, (in the direction of an angle of 45° with the horizon, the lower end of the diameter being to the west of the moon's centre, measured with an achromic object-glass micrometer of 40 feet focus, and found to be = 31′ 31′′.7,—On the 7th May, at...

[ocr errors]

a Libræ passed the meridian, at.

Preceding limb of the moon on the meridian, at
Subsequent ditto, at ....

Penumbra, sensible at

Diameter of the moon, 31' 26", measured again, at...

11h 35m 0$

[ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small]
[blocks in formation]
[ocr errors]
[merged small][ocr errors][merged small][ocr errors]

Beginning of the eclipse, through an achromic opera-glass, at ..
Shadow very dense on the moon's limb, at....

So that I conclude the eclipse began at
The times above are apparent times.

[ocr errors]

LXXXIX. Observations on the same Eclipse. By Dr. Bevis. p. 543. Apparent time.

14h 8m os A discernible penumbra on the moon's limb.

14 20 The beginning of the eclipse, by the bare eye; but doubtful to about a minute, from the dilute and uncertain termination of the true shadow.

XC. Of a Remarkable Monument found near Ashford in Derbyshire. By Mr. Evatt, of Ashford. p. 544.

In the year 1759, as some people were making a turnpike road through the village of Wardlow, near this place, they thought proper to take out of an adjoining field a heap of stones, that had lain there time immemorial, and without any tradition why it was thrown together in that place, though it was manifestly a work of art. Here, to their great surprize, on removing the stones, they found a monument, to the memory of 17 persons, or more, who had been there interred. The bodies appeared to have been laid on the surface of the ground, on long flat stones, and their heads and breasts protected from the incumbent weight of stone, by small walls made round them, with a flat stone over the top; excepting 2 principal ones, which were walled up, and covered from head to foot, in the form of a long chest, with a stone cover over each. On removing the rubbish, many bones, such as jaw-bones, teeth, and the like, were found undecayed; but none at all of the larger bones of the body. The heap of stones that covered them was 32 yards in diameter, and about 5 feet high; and the stones of which the coffins or tombs were composed, appear very plainly to have

been taken from a stone quarry, above a quarter of a mile distant. They were disposed in a circular form, but a part of the circle is vacant; though it is probable it was not so at first; as there were found several bones and teeth in that space; the cause might be, that as part lay next the road, it might have met with an accidental disturbance; or, what is yet more likely, the people that came to draw the stones away, beginning on that side of it, destroyed that part before they were aware that it was any ways remarkable or worthy note.

There is one circumstance that seems to denote the monument to have been rather modern, which is this: It appears from the best observations he could make, that a wall of the field cutting off a small segment of the circle, marked d, was erected before the monument was made, as it is hardly probable that the persons who built it, would be at the trouble to remove that part of the circle that was without, for the sake of building a field-wall entirely level; which is the case, for all that portion of the circle, from the inside of the wall, was as level as any other part of the field; and as walls are not probably of very ancient date here, (if the above be a fact) he concludes, that the monument must have been erected in some of the wars of the houses of York and Lancaster, or later. The several coffins were about 2 feet high each: the two complete ones about 7.6 long each; and the others had the flat stone nearly the same length; but the covering extended only as far as the breast.

XCI. Description of the Hiero Fountain at the Chemnic Metal Mines in Hungary, erected in the year 1756. By Wolfe, M.D. From the Latin.

p. 547.

This machine, though it has nothing new, seems not unworthy to be known, both as it is thought the only one of its kind, applied to a large work, and because of the singular generation of snow and ice, observed in its operation.

In pl. 15, fig. 1, N is a wooden cistern at the middle of the mountain, at 143 feet above the horizontal plane, into which the waters from a higher mine are received. o is a similar cistern, at the top of the mountain, 260 feet above the plane, into which the rain waters are led for assisting the work. A is an air vessel, at the foot of the mountain, into which the water from the cistern N or o is emitted, by the tubes RT or GT, and the cock H, by the force of which the air is compressed, and propelled through the tube LMM into a lower vessel. в is a similar vessel in the bottom of the mine, 104 feet below the vessel A, which receives the water from the cistern D collected in the mine, which, being compressed by the force of the air coming from the upper vessel, is raised and discharged through the tube asF. K is a tube with a cock for letting out the water from the vessel A, after the work is finished, for which purpose also the tube I sometimes serves. L transmits or stops the air. The cock E of the little tube ought to be open, 4 M


while the water flows from the cistern D through the tube acp into the vessel B. At the orifice of this, snow and ice are generated. P and s are small valves, to prevent the return of the air from the vessel B, and the water from the tube Fs.

The operation of the machine is performed thus; two men being ready at the vessels, and the cocks being all shut, and sufficient water being let into the tubes RT and GT, from the cistern N or o; first they open the cocks c and E of the lower vessel, and quite fill the lower vessel with water from the cistern D. Then the cocks c and E are shut, and H and L of the upper vessel opened, so that the water, flowing in through нx, may leisurely fill the vessel, and compressing the air, thus force it through LMM into the lower vessel; the water begins then to flow out at F, till the vessel A be hardly half full. The vessel в being thus B nearly emptied, H is shut, and the pipes K and I opened, the greater part of the water is let out of the vessel A. Then K and I are shut again, L opened, and the air returns into the vessel A with a loud noise. Lastly L being closed, the operation is finished, till it be proper to repeat it.

When the work is performed with the water from the cistern N, which is saturated with nitrous and sulphureous particles, if in the foregoing operation, the air being returned by opening the cock L, and the tubes c and E opened, a kind of snow is always generated at the orifice of the tube E, and collected like a cap about it. But if, after the said operation, the cock L be not opened, and so the air remain in a state of compression, on opening the tubes c and E, the cap, instead of snow, is formed into a firm and thick cap of ice. But nothing of this kind happens when the operation is performed with the rain water from the cistern G.

The measures of the parts are as follow ;

Of the vessel A, the diameter 49 inches, height 54 inches, thickness 14 inch. Of the vessel B, the diameter 324 inches, height 60 inches, thickness 14 inch. The tubes RT, GT of iron, diameter 44 inches, thickness 14 inch.

Also the diameter of Fsa 34 inches. inches, the lower 1 inch, and thickness

The Chemnic foot is to the Paris, as

LMM tapering, has the upper diameter 2 14 inch.

1538 to 1440, the pound as 106 to 92.

A cubic foot of the mine water weighs 72lb.

The vessel A contains 57 cubic feet, в 27 cubic feet, or 22 amphoras.

At each operation there is raised 25 cubic feet, sometimes 31, differing only in time, as the water flows in from N or from o; and there will be performed 20 or 21 repetitions of the operation in the one case, in the other only 17

or 18.

XCII. Of a remarkable Marine Production.* By Alexander Russell, M.D., and F. R. S. p. 554.

Extract from Dr. Nasmyth's Letter, who brought the animal from America. "At my return from North America, in November 1759, I sent you 2 or 3 articles picked up in that country. One of these, from its singular appearance, and from its being a perfect stranger to every body that saw it, I must now recommend to your attention. The desire of keeping it entire, and as it was found, prevented any other investigation, than that of viewing it particularly, when I first got it, and at times afterwards, to be assured of its safety, as well as to observe the changes it might undergo while it continued in spirits.

In June 1759, the squadron destined against Quebec arrived in the river St. Lawrence, when being in the latitude 49° 50′ north, and about 10 leagues to the westward of Anticosti, (an island in the mouth of the river) we sounded, and struck ground in 42 fathoms; the soundings white sand and black specks. Having at the same time thrown overboard a fishing-line, the hook was found strongly attached at the bottom; and after some efforts, brought up a piece of rock, into the surface of which was inserted a strong tendinous substance of a light brown colour, in length about 7 inches; it was round, and nearly of the thickness of a common goose-quill; the other end formed a sack, or bag, of the size and shape of a pigeon's egg. The whole of this substance was elastic; and on pressing the bag, I plainly discovered a contained substance, and imagined that it was attended with motion."

[Thus far Dr. Nasmyth.]

On examination of it, by Drs. Solander and Russell, and Messrs. Collinson and Ellis, it appeared to come nearest to what has been by naturalists called Priapus; they therefore named it Priapus pedunculo filiformi corpore ovato. The body was oval, and in size between a pigeon and pullet's egg, smooth, membranous, and of a silver ash colour. What appeared to be the mouth, was situated a little below the apex, and was quadrivalvular, in the form of a (+) cross. The anus was on the same side, a little above the base, or insertion of the stalk, and also quadrivalvular. Towards the aperture of the mouth and anus, the body felt more callous. From this body issued a peduncle, or stalk, of 10 inches in length; This stalk was of a light the extreme end of which was fixed to a piece of rock. brown colour, about the thickness of a large hen's quill, round, hollow, rough, and of a membraneous, leather-like substance. When the body was opened, the internal coat appeared to be composed of reticular fibres. The interior orifice of

This animal, which was referred by Linnæus, in the twelfth edition of the Systema Naturæ to the genus Vorticella, under the name of Vorticella ovifera, is a speices of pedunculated Ascidia; and is the Ascidia pedunculata of the Gmelinian edition.

« PreviousContinue »