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the end of November there fuddenly fettled on the levels near Chichester a moft prodigious number of web-footed birds; a migration thought by fome to forefhew hard weather; but, perhaps, it might be owing to the perpetual cannonading in the Low Countries, where probably thofe forts of birds breed, and where there is not, at prefent, any reft either for man, beaft, or fowl.

Generally fpeaking, the weather continued dry and bright through all November, and during part of December*. On the 4th of the laft-named month there was ice for the first time, and ice occurred again the next day. On the 10th the weather fet-in ftormy and wet. It seems extraordinary, that, after fo dry a fummer, and during fo fair an autumn, the conftitutions of men Thould difpofe towards putridity; yet fuch was the fact, a virulent and tedious kind of putrid fever, in fome cafes accompanied by a fore throat, and in others by a nervous fever, prevailed generally, infomuch that many people, died; the union of the two fevers was dreadful in the extreme.

Very unfortunate it is, that, in the year after the prevalence of the contagion amor goo the hogs, fo great a call thould arife for thofe animals at the Victualling office; and that that demand fhould be more confiderable than it ever had been in any preceding war. This increafed demand is owing to the unprecedented number of commiffioned fhips, and to the idea lately taken up, that pickledpork anfwers better on-board the fhips than falt-beef. Thele circumftances have raised fwine to fuch an immoderate price, that, fhould a ftrange hog-herd bring fome to fale in thefe parts, he would find that he might adopt the old adage of," I have brought my hogs to a fine market!" literally. A healthy yearling pig, of the bangling-ear breed, here fells for 31. 10s, unfatted!

Notwithstand ng this fcarcity of hogs, one cannot but contemplate with wonder the quantity of provifions that England is affording: fleets are plentifully vialled, camps are properly fupplied, and an hoft of aliens are liberally fed, with the produce of this little ifle! We feed the Emigrants, the Jews expelled from France, the prifoners on parole, and the

Awafp was difcovered this month in Ottery St. Mary, on the wing; and on the 27th the robins were as melodious as in the month of March, and the flower, called Heart's Eafe, in full bloom. F. SMERDON.

5

Sans Culottes we hold in prifon. These
latter never lived fo well in their lives-
before they are allowed every day three
quarters of a pound of gond beef, twa
pounds of bread with all the fineft of the
flour in it, the bran alone being extract
ed, two quarts of trong well-retifhed
foup, one pound of cabbage with the
heart included, and a quart of good beer.
As a Frenchman can live upon one
pound of meat for a week, this allowance
is over plenteous, and the prifoners fell-
more than half of it. With the money:
fo obtained they buy as much strong-
beer as they can get leave to have brought
them. The wounded are allowed two
quarts of beer a-day, bread made of the
fineft flour alone, and fuch other articles
of diet as are judged by the furgeons
moft befitting their fituation. Such is the
manner in which Englishinen are at this
juncture treating their natural, invete-
rate, and unalterable, enemies; for, fuch
the natives of France of all defcriptions
are, and ever will be, whatever may he
faid to the contrary by our fine folks in
favour of the Emigrants, or by our De-
mocrats in favour of the Sans Culottes ;
a fact that will be one day exemplified
by the French Royalists and Patriots com-
promifing their differences, and turning
their arms united against England and
her Allies, but more particularly against
England. Although I am a simple ruí-
tick, time will prove me to be a prophet
at least as good as old Nixon, one of
whofe prophecies is likely to be again
verified, viz. "There will be a winter
council, a careful Christmas, and a
bloody Lent!" A SOUTHERN FAUNIST.

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MEMOIR RELATIVE TO WEIGHTS
AND MEASURES. BY M. PELLIZER.
No
certain rule has hitherto been
found, by which a standard might
be eftablished in order to fix true weights.
and meatures all over the world; but,
before it can be fixed, clear and diftin&t
ideas muft be had of what is demanded.

First of all, meatures of length mut be diftinguished from weights. A meafure is nothing else but à dift.nce in a frait-and known line, situated betwixt two points. The opening of a pair of compaffes, of parallel points, carried all over the world, would always be the fame. But this kind of measure would be indeterminate and inconvenient; and it would be neceflary to fee it, in order to get acquainted with it. The rod of a pendulum which beats the feconds requires the fame length, all over the

earth,

earth, to produce every where the fame movement, meafuring time equally, and, may be taken as a fandard for measures, by dividing it into three equal parts, which might be called feet. This meafure would be known and fixed all over the world (fee the Supplement). The accidents which happen to this meafure when made of metal, in growing longer or fhorter in the different climates of the earth, would not hurt the equality of length when the pendulum measures time truly; and the fubdivifions which would be given to the foot would be equally fixed and known. This rod or pendulum is, by the prefent meafure, three feet eight lines French meaf. But it is not fo with weights. Weight is nothing else but the tendency all bodies have to defcend to the centre, though fome other body keep it off This tendency is then a neceflary refult from the mafs or collection of corporeal particles which happen to be in every body, and which alone caufes the mo tion of bodies towards the centre, provided there be no other body refifting to this tendency, or that no other motion be given. Hence it is neceffary that the bodies which contain more parts in the fame fpace fhall weigh heavier, and thole which contain lefs fhall weigh lefs. Hence it follows, that bodies weigh equally in their elements, as they do not weigh differently, but in proportion to the parts, the denfity, the mais, they contain in the fame space.

The longitudinal measure may be adopted to all bodies, every way and arbitrarily, as not one fingle phyfical effect is known to depend from a given meafure, except the length of the pendulum. But there are three only which produce the effects in bodies, either in themselves or relatively to other bodies. These three meafures or dimenfions are, the length, the breadth, and the depth, which are infeparable properties to all bodies. They can be neither separated nor phyfically divided among them; and where one of these three dimentions phyfically meets, the other two must meet alfo, though the human understanding may confider them feparate. Length and breadth being unequivocal, and of the fame analogy, they produce in bodies the first aggregation or multiplication of parts which form furfaces. From this aggregation of parts come to bodies the weight of mats and incerti. tude, in which all bodies ought to be equal in proportion to their mais. But

as from these two dimenfions, length and breadth, depth cannot be phyfi cally feparated, it follows, that the latter, by multiplying the furfaces, com-. pofes folids, and produces in bodies another kind of weight, called specific gravity, and effentially belongs to depth, which is the fame thing as height. Thefe two forts of weights can no more be phyfically divided into bodies than the three dimenfions among themfelves; but they are diftinguished in the bodies by the different effects they produce. The effects of the weight of mafs are different from the effects of that of fpecific gravity. Nobody has ever been able to difcern the effects of fpecific gravity in folid bodies. Archimedes found the means of knowing its difference in bo dies but by plunging them in water. In this manner it may be feen how much more mafs or denfity there is in a body heavier than another which is not fo and which differs in fpecific gravity; for, the heaviest body, taking-up lefs space, removes alfo lefs water; and the difference in the weight is equal to the quantity of the water removed, in an inverted manner.

Fluid bodies have alfo the two weights jul now mentioned, thofe of mass and 1pecific gravity. Torricelli was the first, among the moderns, who observed the eft&ts of specific gravity in fluids, and who perfected the art of hydraulics, in fhewing that fluids may be fucked up wards, to the height only which reprefents the specific gravity of each fluid. The difference there is between the weight of folid bodies to that of fluid bodies exifts but in the manner by which Nature expreffes them; for, all fluids are feen to weigh equally, from bottom to top as froin top to bottom, which is commonly called refistance, without their deviating, at the fame time, from the general law of univerfal tendency to the centre. From this fingularity of fluids follows this ininitely-plain truth, that all fluids are in equipoife below their level, and produce no other effect but that of their senttance from below upwards. I have fhewn, by my hydraulic experimen's, published fome years ago, that truth which deftroys the preffure of the atmosphere as a thing impoffible to a fluid in equilibrio. The height where a fluid keeps itfelf is but the mete effect of specific gravity. The height at which fluids keep themfelves changes according to the change which happens to bodies in their pecine

gravity;

gravity; and this specific gravity changes in proportion to their being diftant from the centre of the earth. So that I lay it down as an invariable rule, that the farther a body removes from the centre of the earth, the more it weighs, in what ever latitude of the earth you please. All fluids demonftrate this rule, and the barometer efpecially, which defcends in the tube in proportion as we afcend a hill, and afcends in proportion as we defcend, by reafon only of the augmentation or diminution of its specific gravity. Nature, being every where the fame, ought to preserve at Paris the fame laws one wishes her to have at the 45th degree of terrestrial latitude. Convinced of this truth, and of all others which my former experiments had prefented me with, I applied to two ingenious artifts in mathematical inftruments at Paris; the one made fcales for me, with the utmoft nicety and all the precaution my defign required. We equipoifed at his houfe two weights, the one of lead, the other of German glafs. We afcended, all three, the top of the tower of the cathedral of Notre Dame, and there we found the crystal weighed heavier than the lead. The barometer marked two lines and a half (Paris measure). This height appearing to us not fufficiently elevated to make a good experiment, we went to the Calvary, where the barometer marked five lines and a half, and where we conftantly found the crystal weighing heavier than the lead. This effect is fimple and natural. The atmofphere being lefs refiftible above than below, it refifts more below than above to the body, which is most expanded, as is the crystal in its tendency to the centre of the earth. Confequently, being weighed above, the atmosphere refifting lefs to that body, it fhews the overplus of the mafs it wanted to equipoife below. This experiment is proved under the recipient of an air-pump, when the most expanded body weighs heavier in the vacuum than in the atmosphere.

This experiment, which, at first fight, contradicts my principles on the diftance of the centre of the earth, which thewed me that, in weighing directly the two bodies, I did but try them as weights of mals, and not as weights of specific gravity. In confequence, I took up the latter in making the fame experiments in water. I weighed then the cryftal and lead on the borders of the Seine, in two veffels filled with water; and, ha ving put them in equipoife, in adding

4 ounces of lead to the cryftal, I found that at the top of the fteeple of the Calvary the two weights had loft their c quilibrium, that the lead very fenfibly weighed the heavieft, notwithstanding the cryftal had been loaded with fome lead; and that, having defcended to the borders of the Seine, the two weights had resumed their equilibrium; confequently, the fpecific gravity of bodies changes in proportion to their distance from the centre of the earth, as the bor ders of the Seine and the top of the stee ple of the Calvary demonftrate it.

This difcovery naturally induced me to conftruct a new inftrument, which I fhall call a Metrometer, or Regulator of Weights; which, without ceafing to be a barometer, will, at the fame time, be a certain rule for making weights of an entire equality, not only in a certain country but all over the earth. The Mercury in the barometer varies of about four lines by the preffure of a pound weight, of whatever density or fpecific gravity it be. But this effect totally depends, in refpect to its identity, on the meafure which will be given to the cavity of the fyftem of the barometer, the measure of which ought to be previously fixed upon.

The principal effect this inftrument will have is, to fet a hand going, fo that a certain given weight will force this hand to defcribe a circle of about 24 fect; half the weight 12 feet and a grain, 2 degrees and a half, or thereabout, of the circumference of that circle.

The fame motion of the hand of this inftrument, at the fame height of the barometer, will produce, all over the furface of the earth, the fame weight; and this is what is required. Supplement for the Longitudinal Measures.

I have given, in my Memoir on Weights and Measures, the length of the pendulum, which beats the feconds, in all the Jatitudes of the earth, at Cayenne, at Paris, and in Lapland, as a fet rule. My reafon for it is plain; time being every where of the fame duration, the inftru ment which meafures it exactly in one place ought to be the fame every where; and, if the length of the pendulum is, at Paris, 3 feet 8 lines long, it will be of this very fame length at Cayenne and in Lapland, where the pendulum would not mealure time exactly, were it either fhorter or longer than 3 feet 8 lines

100

This affertion is abfolutely contrary to the opinion of the Academy of Sci

encee

ences at Paris, according to M. de la Lande, in his Abrégé d' Aftronomie, No 606; in which he affirms, that the length of a pendulum ought to be, for its measuring time truly at Cayenne, er under the Equator, 3 feet 6 lines 70 at Paris, 3 feet 8 lines; at Ponoi, in Lapland, 3 feet 9 lines; and the difference in these two extremes is 2 lines 47

I lay down as a fact, that this difference proceeds only from the expansion or contraction of the metal the pendulum was made with, from the falfe meafure made ufe of to afcertain its length,

and not from the variation of the meafure requifite for the pendulum to meafure time.

The truth of this is clearly demonftrated by the first experiment of this kind made in 1642, by Mr. Richer, of the fame academy. He carried to Cayenne a clock which marked the feconds with exactnefs at Paris, and this very clock happened to go flower at Cayenne, by two minutes in 24 hours. Mr. R. fhortened its pendulum, to make it beat the feconds at Cayenne; confequently, the heat of the climate had lengthened the pendulum to more than what was requifite for beating the feconds.

The fame gentleman took with great care, at Cayenne, in an iron rod, the length neceffary to make the pendulum beat the feconds at Cayenne; and, ha ving brought that rod to Paris, he found the length required for beating the feconds at Paris had got fhorter by one line and quarter, which was the neceffary measure to beat the feconds at Paris.

From this fact of the most authentic experiment that had been made among the moderns, and which clearly thews an equal length to be as neceffary to beat the feconds at Cayenne as at Paris: the contrary of this has been concluded by the Academy of Sciences.

In later times experiments have been made with the Paris foot to know the length of the pendulum which beats the feconds at Cayenne, under the Line, at Lapony, and at the Polar circle; but that inftrument being expofed to the excefs of the heat and cold of thofe two climates, the meafure receives the fame influence as the weather; in confequence of which, it is impulfible to find true measure.

*Aline is the 12th of an inch Paris meaf.

I thought, having found it in the manner of measuring geometrically the terreftrial femidiameter, by means of two perpendiculars, of about 1000 of 2000 feet in length, the two inferior ends of which should be where the cir cumference of the earth is, on the feafhore at high-water, the two fuperior. ends fhould mark a fecond circumference. In drawing to thefe points two inferior and fuperior cords, the difference of the one to the other would give which, with the fame difference of all a length towards the fide of the angles; lars, would interfect the other, the dif the parallels to one of the perpendicu tance of these two perpendiculars fhould be at least 100 feet afunder. This geometrical operation (notwithstanding all the difficulties attending it) would be more fure than the measuring an arch of nine degrees on the meridian. I thought to have found in geometrical thumb-nail, taken 8, 16, or 24 times, figures, formed after the length of the which figures might correct themselves, tion of the angle, which should be fet a greater or smaller quantity in a variafor a given quantity; but I could not convince myfelf of the certainty of this operation, on account of the extreme difficulty of the art of true divifion.

Thefe difficult operations led me to make experiments on the dilatation or expanfion of metal; and it is that which gave me the means of having a true ftandard in all the climates of the earth; and it will ferve likewife to prove against the wrong affertions of the Academy at Paris,-that the pendulum is not of a different length, under any climate of the earth, when it beats the feconds truly.

meafure which deferves more than I do not know, in all nature, any another to be called natural, except the length of the pendulum, which produces the natural effect of measuring time; tion of the earth. The meafurement of that is to fay, the day or diurnal mothe femidiameter of the terrestrial circumference is an operation too difproportionate to the faculties of man to be abie to make it with a geometrical precifion; and this is the very precision which is required. It is this precifion I propofe in the dilatation of the two metals together, yet feparate from one another, and at full liberty, to the end that any one, with his own eyes, may fee by how much his measure varied, and know how to bring it back to its

true

true length, were it difplaced but an is evident that the fame measure has hundredth part of a line.

Metbed.

Take a very fmooth brafs rod, long enough to be able to trace on it the length of a pendulum meafuring time exactly, from the point of fufpenfion to the centre of gravity. This rod muft be affociated to another of iron, of equal length, like a fector. Through the centre of the joints of these two rods a line is to be drawn acrofs, at rectangles with the two fides of the two rods. Confe quently, the infide contact of the two rods must be as perfect as poffible, and the furface of the two rods muft make but one, and a very fmooth and even ene. In the two rods at the other point of the other extremity another tranf verta! line, like the first, mufl be drawn, which is to contain exactly, from the other line, the length of the pendulum. In the two lines, and on the fide of the iron, two flat rofe-diamonds may be fet, in each there is to be a point, wherein the very sharp points of the compafles are to be placed, to avoid spoiling the line by the repeated taking of the length. In the breadth of the iron rod a line, from one end to the other, may be drawn and fubdivided. The inftrument may alfo be lain, as it were, in a loose wooden frame, fo as to have both furfaces expofed to the impreffion of the climate.

In this fituation it is evident that the two rods, joined at one end, will not be able to dilate or fhorten themselves but at the oppofite end. It is evident alfo, that the braf's rod will dilate itfelf more than the iron one, which will dilate alfo, by the fame caufe which will dilate the brafs rod. Therefore, when the cold wil fhorten the iron rod, the brafs one will shorten too, but more, as brafs is more dilatable than iron. In both cafes the tranfverfal line, drawn to the centre

of the joint of the two rods, will under

go no aiteration; but the other tranf verfal line, drawn at the other extremity of the inftrument, and which ends the length of the pendulum on the fame furface of the iron and brass, will prefent an account of the greater dilatation of the brafs, two lines inftead of one; that of the brass rod will go beyond that of the iron rod by the dilatation, and the farme line more behind that of the iron rod by the contraction.

In these two contrary cafes contrary caules must be made ufe of to replace the two lines, in order to make but one of them; and every time it is done, it

been found which had been fixed upon at irft, à lined. If then the heat of the climate, or the artificial heat, removes the line of the brafs rod from that of the iron rod, cool the two metals till the two lines form but one again. As thefe two lines ought to be as fine as poffible, and the two extremities of the rod extremely even, a good glas muft be made ufe of to be able to difcern them well.

If, on the contrary, the cold should contract the brafs, and remove its line from the line of the iron rod, the inArament must be heated till the two lines form but one, and confequently be at the fame difiance thefe two lines had been fixed from that of the other end. In order to demonftrate it, these two means of cold and heat may be employ el in every climate, as they are in the place where the inftrument is made; for, in taking with a pair of compaffes the length of the two lines, and res moving them afterwards by heat or cold, the compaffes will fhew by how much they are difplaced; and every time the two lines form but one it exactly anfwers the length taken with the compaffes. It is then evident that, by thefe means, the lame length will be had in every climate of the earth; confequently, the fame meature to which all others will be referred with the fame exactnefs, the mistakes of the hand excepted.

Every mathematical inftrument maker will be enabled to make his inftruments more correct, obferving, by this inftrument, the variations they experience ja the conftruction by the varied influence of the change of the variation of the weather.

Mr. URBAN, Adderbury, ÓB. 1. YOUR Literary Intelligence is cer

tainly very acceptable to many of your readers, and, in common with others, I am much pleased with it; and thank you for this and numerous other inftances of Urbanity exhibited in your zeal to oblige. I read with particular pleafure the intelligence communicated in p. 536, refpecting the works of Pope and Dryden, and rejoice to understand they are in fuch good hands, especially Dryden; as I believe it is impoffible to procure a complete and uniform copy of his Works. Both, as eminent authors, deferve to be handed down to pofterity with the moft fplendid advantages of

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