out of humour when I order them to burn the oil extracted from the Nummaria.

The Nummaria appears in May, and is ripe about the middle of June. In its maturity the leaves open and scatter the feed; wherefore, in order to make a provision, it must be gathered a little earlier. By cultivating it, you may have it twice a year, if it is fown in March, and in the end of June; and this is very often neceffary, because it doth not grow every year. It loves á particular temperature of air, of which I have no certain knowledge; but I am pofitive, whenever it be gins to grow, it must not be difturbed by any tillage: the more the earth about it is turned up, the more its maturity is retarded."

Upon examining the grain of the Nummaria, I found that it contain ed an oil. It happened, that fome years fince I fowed about four acres of ground with turneps, not one of which grew up: but then, instead of thefe, I had fuch a prodigious quantity of the Nummaria, that one would have thought that my land had been fown with it. To make amends in fome measure for the lofs of the turneps, I refolved to gather the Nummaria, and extract its oil. Accordingly I cleared the ground entirely of this plant, of which there were feveral waggon loads, and piled it up in my granary. In two days time, it heated, for which reafon I fpread it out as much as poffible, that it might dry more eafily; and afterwards it was threfhed. It is not poffible to conceive what an abominable ftink it fpread, not only in the granary, but alfo in the contiguous buildings; and even in the court-yard it was infupportable.

Several years before, fome ye full of white worms had been laid up in that granary: they were in fuch vaft numbers, that at the ufual feafon of the metamorphofis of infects, they crawled out of the heap,: which they covered in fuch multitudes, that with a rake they were gathered in bufhels; and yet, notwithstanding the heap of corn, feemed overfpread with a yellowifh living matter. When fome time after the rye was carried away, the vermin did not abandon my granary; they had made a lodgement there, and in fpite of all my. efforts, and all the remedies I could procure, I could never exterminate them. The new corn brought in was always found, in four and twenty hours, covered with a white web, formed of the kind of filk which is fpun by that vermin.

Difheartened by a thousand expenfive and unprofitable projects, I became accustomed to that difagree. able object. I was even fo indif ferent, that when my granary was emptied of the Nummaria, and the rye was covered off, which I had feen before covered with white worms, I imagined, as none ap peared at that time, that their metamorphofis had been advanced by fome caufe to which I was a ftran ger. Upon reflection, however, I conceived fome fufpicion of the fmell of the plant, and I refolved to make the experiment the first opportunity that fhould offer; and indeed it was not long till one prefented itself.

The following year I had fome corn brought to me full of white worms: immediately I ordered the Nummaria to be fought for; and as only a fmall quantity of it could be gathered, I commanded a ring

or circle to be made with it round the heap of corn, which was very confiderable. It was trod upon, that it might diffuse the fmell more ftrongly, and the fuccefs juftified the idea I had conceived: the white worms disappeared, and fince that time, I have never perceived one in my granary. All my neigh bours, to whom I communicated this discovery, have reaped the fame advantage from it, and it is with pleasure I impart it to you, that the whole kingdom may be indebted to you for the fame ob ligation.

As thefe worms are not found in all countries, every body is, not ac quainted with them; and amongst those who are, perhaps there may be fome, who in order to get rid of them, would fcarce expofe themfelves to the naufeous ftink of the Nummaria; for we must acknowledge, that vermin destroys the corn but very little. Thefe worms never attack it on the fide of the fhoot; they confume but a fifth part of the flour, and never commmunicate to it the least bad taste.

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The corn, therefore, if fown, grows as well, and produces as plentiful a crop as any other; and if ground into flour, gives as good and as nourishing bread as one can defire, without the leaft danger to the health; a fact of which I am well affured by my own experience. But, befides that they diminish the quantity of the corn, they give it fo difagreeable a colour, that it is a difficult matter to fell it. The gain, therefore, is evident in exterminating and destroying them by a cheap and infallible remedy, far fuperior to others, which are often expenfive and ineffectual.

I forgot to inform you, that the oil, the remaining fubftance after the oil is extracted, the leaves, the branches, the trunk of the Nummaria, are feverally endowed with the fame virtue as the whole plant, because they preferve the fame fmell. I experienced this with one of my neighbours, in a year when that plant failed entirely. I order ed fome to be boiled in water that diftilled from a dung hill, and after removing the wheat, we sprinkled plentifully, the place where it had lain. When that place was well moistened, we let it dry, and after wards put the wheat upon it. We washed in like manner the fecond place which the wheat had occupied. In three days time no maggots or worms were to be seen.

The black worm, which gnaws the corn entirely, leaving nothing but the bran, is far more danger ous, I am not certain if the Num. maria deftroys that infect or not, having never made the experiment; but I am inclined to believe, that it is an enemy to all vermin, for I could never perceive a caterpillar upon its leaves; and it is very probable, that with the white it destroys alfo the black worm, caterpillars, bugs, wood-lice, wevils, and a mul titude of other infects, which infeft and confume our most valuable effects. (Journal Oeconomique.)

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M de la Nux, of the ifle of Bourbon, a correfpondent of the academy at Paris, has advised M. de Reaumur to make ufe of tobacco either green or in rolls, as a prefervative against wevils: thefe animals, who are apparently liquorith, will come to the tobacco from all parts, and as foon as they have eaten of it, they certainly die.

A demonftration of the accuracy of the trials made with Mr. Irwin's Marine Chair, for finding the longitude at fea, by Jupiter's Satellites. By M. De Lle, of the Royal Academy. of Sciences at Paris, Fellow of the Royal Societies of London, Berlin, Stockholm, and Upfal, and late Principal Aftronomer in the Impes rial Academy at Petersburgh..

N the Journal Etranger, for the

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with a short defcription of this Marine Chair, invented by Mr. Ir win, for obferving the longitude at fea, wherein it is faid, that Mr. Ir. win, on his return from a voyage he had undertaken to make trial of it, found that he was not mistaken above twenty-three miles, or about a third of a degree, in his eftimate of the longitude, from the feveral obfervations he had taken; that is to fay, that, by means of his machine, he had obtained the longitude to a greater degree of precifion than the act of parliament, made in England, requires.

As the Journal Etranger abovementioned recites the journal and particulars of thefe firft obfervations, made with Mr. Irwin's Marine Chair, by Mr. Jeremy Siffon, I thought proper to examme into the exactness of them, by means of correspondent obfervations made at Paris and elfewhere, to fupply the uncertainty of the calculus which Mr. Siffon had only to rely upon. he not knowing of any correfpondent obfervations that had been taken. I have alfo compared his observations and their correfpondent ones, with the pofition of the ifle of Ufhant, within fight of which Mr. Siffon obferved, the 9th

Siffon, is that of the first fatellite, the 9th of Auguft, in the evening, which he found to happen at fea, at 7 h 55 min. 1 fec. Tobferved it at Paris, at the Hotel de Clugny, with a 22 foot telescope, at 8 h 20 m. 42 fec: and M. Meffier, with a New tonian reflector, of four feet and a half long, which magnified 56 times, 15 feconds later. By comparing M. Meffier's obfervation with Mr. Siffon's, the place where the latter then was should be 25 m. 52 fec. of time weft of the meridian of Paris, or 16 m. 14 fec. weft of the meridian of London, on fuppofition, that the diftance of London from Paris, is 9 m. 41 fec, as marked in the Connoifans des Temps. Mr. Siffon makes the difference of longitude between London and his place of obfervation, 18 m. 16 fec. or 4 h. 34 m. 15 fec. and he adds, that his obfervation was taken in fight of Ufhant. Now, according to the general chart of France, regulated by triangles, the ifle of Ufhant is weft of the meridian of Paris, 7 d. 24 m. 33 fec. from whence taking 2 h. 25. m. for the distance from London to Paris, there remains 4 d. 59 m. 33 fec. for the longitude of the place of Mr. Siffon's obferva.

tion, weft of London, which gives the longitude of the ifle of Ufhant, with respect to London, 25 m. 18 fec. less than it is marked on the chart of France. This difference of 25 m. is certainly but a minute error for an observation of the longitude, as it amounts to no more than fix marine leagues. But, to reason a little further; probably the error might turn out fill lefs, if we could introduce into the account, the bearing and distance the fhip then was from Ufhant, and the difference of the telescopes with which the correfpondent obfervations were made: it is well known, that an emerfion of the fecond fatellite may be seen 30 feconds fooner with a reflecting telescope of four feet, than with one of two feet, which would again diminish the error by about a third; and were we to fuppofe that the ship, which, according to the relation, was in fight of Ushant, was three or four leagues diftant from it, the error would abfolutely vanish.

Laftly, it is to be noted, that the Jongitudes marked on this chart, and calculated from a series of triangles, as they are expreffed in two columns, graved at the fides of the chart, were computed by M.Caffini, and his affiftants, under the hypothefis of a spherical earth; whereas they fhould be lefs in the hypothefis of an earth oblate towards the poles. Thus Mr. Siffon's obfervation agree better for the pofition of the ifle of Ufhant, with the figure which we now know the earth has, than with the determination deduced from the measure of the parallel of Paris in the hypothefis of a spherical earth. This is a proof of the goodness of Mr. Irwin's Marine Chair, and the

exactness that may be arrived at in the obfervations of Jupiter's fatellites, made in it.

The other obfervation of the fatellites by Mr. Siffon, of which we have a correfpondent one, is the emerfion of the second, on the 13th of Auguft in the evening, which Mr. Siffon has noted at 11 h. 21 m. 54 fec. By an obfervation made at Vienna with a four foot Newtonian reflector, this obfervation fhould have happened at London, at 11 h. 44 m. 35 fec.*; and confequently the place of his obfervation was weft of London 22 m. 41 fec. Mr. Siffon marks this difference of longitude 24 m. 25 fec. not having had any correfpondent obfervation, and being obliged on that account to refer to the tables.

Thus we fee plainly, that navigators are, for the future, to confider the invention of the Marine Chair, as one of the greatest benefits that can poffibly accrue to their fcience. The knowledge of the longitude, which is fo effential a part of it, and fo long defired, is now brought to its utmost perfection, if, by this new means obfervations can be made as well at fea as at land. The heavens are continually offering proper phænomena for finding the longitude, and the greateft difficulty has, till now, been, how to obferve them well. It is therefore of the utmoft importance to be more and more fatisfied, by repeated trials of the goodnefs of this method. I make no doubt, that, in a fhort time, the navigators in general, jealous of the progrefs of their art, will difpute the glory of having firft profited by fo excellent a discovery.

Useful

ATHING in the fea-water, in hot climates, is very wholefome when done with difcretion. It should never be immediately after meals, for reafons obvious to thofe who are acquainted with animal nature and oeconomy. Bathing in, and drinking the falt water is a Specific cure for fcorbutic diseases. Cleanliness, and frequent washings, are very beneficial. Sir John Narborough preserved the health of his crew, in a long and unwholesome voyage, by obliging them to have

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ftrict obfervance of cleanlinefs, and particularly by washing themfelves, and being careful to keep neat and fweet their veffels of cookery. Cleanliness also extends itself to apparel and bed cloaths, which should always be with the stricteft care obferved, in the utmost state of poffible purity. One inftance of detrimental uncleannefs, is, lying down to fleep, as feamen too frequently do, in all their cloaths: this fhould never be fuffered; but, instead of being prevented, it is often encouraged, that they may be the more ready at a call. Much fleep in hot weather is hurtful; it relaxes and enervates very greatly, and difposes the body to many disorders. It greatly behoves all feamen who have a due regard for felf-prefervation, never to fleep upon deck, especially in the night, or when the air is moift: for obvious reasons. Let the breaft be covered during fleep. It were perhaps needless to admonish the prudent feamen never to fleep expofed to the fun, rain, or cold winds. Every feaman ought to have three hirts, that he may be able, by keep

ing them duly washed, to change once in three or four days. After linen has been washed in falt water, it should be rinced in fresh water; for the falt particles adhering to it, are hurtful to the wearer. The expence of fresh water would be but fmall, a hundred fhirts may be rinced in a fmall pail of fresh water; but when it rains, even without that charge.

It is very important to the headthinefs of fhips, to be well provided with a plentiful ftore of vinegar; if the feamen nfe it with all their victuals, the better; but especially with pork; and a little in their water too, particularly in hot climates, or intemperate weather. Vinegar corrects evil effects from water inclining to putrefaction, and promotes greatly that falutary perfpiration, which in hot climates prevents putrid fevers and inflammations. If vinegar fails, fpirit of fea falt anfwers, in a very small quantity, nearly the fame happy purpose, as vinegar does in a greater proportion. If a little fhrub was provided for the ufe of the feamen after hard fatigue, inftead of fuch other liquors as are commonly given to them, by generous and humane commanders, on these occafions, it would have a much better effect, as the vegetable acid in it gives it a fuperior efficacy against putrefaction.

On fuch occafions as fickness, how eafily might feamen be supplied with good plenty of excellent and wholefome foup, by the help of a digefter in Papin's manner? By this machine, with a lamp or candle, the bones of any kind of meat-animals might be liquified in a few minutes. How light of charge this engine? How plentifully and readily bones of cattle might be pro

cured?