Such are the most notable phenomena of the earthquake of the 28th of March in thefe countries which have hitherto reached my notice. I think myfelf, however, obliged to notice to your excel, lency, that this extraordinary catastrophe of our afflicted province was preceded by great and extra. ordinary frofts in the winter of 782; by an extraordinary drought and infufferable heats in the fpring of the fame year; and by great, copious, and continued rains, which began in autumn, and continued to the end of January. These rains were accompanied by no thunder or lightning, nor were any winds hardly ever heard in thefe cities where they are used to blow very fresh during all this time; but at the beginning of the earthquake they all feemed to break loofe together, accompanied with hail and rain. For a long time before the earth fhook, the fea appeared confiderably agi. tated, fo as to frighten the fishermen from venturing upon it, with out there being any vifible winds to make it fo. Our volcanoes too, as I am confidently affured, emitted no eruptions for a confiderable time before; but there was an eruption of Etna in the firft earthquake, and Stromboli fhewed fome fire in the last. God grant that the pillars of the earth may be again faftened, and the equilibrium of both natural and moral things restored! I have the honour to be, &c. Account of the Black Canker Cater. pillar, which destroys the Turnip: in Norfolk. By William Mar. fhall, Efq. in a Letter to Charles Morton, M D. F. R. S. Fram the fame Work. Ganton, near Ayifham, Norfolk, SIR, Augufl 22, 1782. A Few months after you did me the honour of presenting my minutes of agriculture to the British Mufeum, I came down into Norfolk, as agent to Sir Harbord Harbord. To a perfon intelligent in mat. ters of agriculture it would be fu. perfluous to fay, that Norfolk is celebrated for good hufbandmen; or that the turnip crop is the bafis of the Norfolk hufbandry. If a Norfolk, farmer lofes his crop of turnips, his farm is injured for feveral fucceeding years; for it is not only the lofs of the immediate profit, which would otherwife have arifen to him from his bullocks, but his land is deprived of the confequent manure and trampling (efteemed highly beneficial to the light lands of this county) on which his future crops of corn are effentially dependant. Among the numerous enemies to which turnips are liable, none have proved more fatal here than the black canker (a fpecies of caterpillar) which in fome years have been fo numerous as to cut off the farmer's hopes in a few days. In other other years, however, the damage has been little, and in others nothing. About twenty years ago the whole country was nearly ftrip. ped; and this year it has been fubjected to a fimilar fate. Many thousands of acres, upon which a fairer profpect for a crop of turnips has not been feen for many years, have been plowed up; and as, from the feafon being now far fpent, little profit can be expected from a fecond fowing; the lofs to the farmers, individually, will be very confiderable, and to the county immenfe. that they might have been collected into heaps, lying, it is faid, in fome places two inches thick. From thence they proceeded into the country, and even at the distance of three or four miles from the waft they were feen in multitudes refembling fwarms of bees. About ten days after the appearance of the flies, the young caterpillars were firft obferved on the under fides of the leaves of the turnips, and in feven or eight days more, the entire plants, except the ftronger fibres, were eaten up. A border under the hedge was regularly spared until the body of the inclofure was finifhed; but this done, the border was foon ftripped, and the gateway, and even the roads have been feen covered with caterpil It was observed in the cankeryear above-mentioned, that, prior to the appearance of the caterpillars, great numbers of yellow flies were feen bufy among the turnip plants; and it was then fufpected, that the canker was the caterpillars travelling in queft of a fresh lar state of the yellow fly; and fupply of turnips; for the graffes, fince that time it has been reand indeed every plant, except marked, that cankers have regu- the turnip and the charlock (finalarly followed the appearance of pis arvenfis) they entirely neglect, thefe flies. From their more fre- and even die at their roots, withquently appearing on the fea-coaft, out attempting to feed upon them. and from the vait quantities which This deftruction has not been have, I believe, at different times, confined within a few miles of the been obferved on the beach, washed eaftern coast, but has reached, up by the tide, it has been a re- more or lefs, into the very center ceived opinion among the farmers, of the county. The mifchief, that they are not natives of this however, in the western parts of country, but come across the ocean, Norfolk, and even on the north and obfervations this year greatly coaft, has been lefs general; but corroborate the idea. Fishermen I am afraid it may be faid, with upon the eastern coaft declare, a great deal of truth, that one that they actually faw them arrive half of the turnips in the county in cloud-like flights; and from have been cut off by this voracious the teftimony of many, it feems animal. to be an indifputable fact, that they first made their appearance on the eastern coaft; and, more. over, that on their firft being obferved, they lay upon and near the cliffs fo thick and fo languid, A circumftance fo difcouraging to induftry, and injurious to the public at large, will, I flatter myself, Sir, be thought a fuffi cient apology for my troubling you with a relation of it, and for my my taking the liberty of fending you a male and a female fly, alfo one of the animals in its caterpil. lar, and one which is in its chry. falis ftate, for your infpection, hoping that the public may be come acquainted with the means of preventing in future fo great a calamity. the nerves or ribs on the under furface of the leaf); thes far I can fay, and I think with a con. fiderable degree of certainty, that having put fome fresh turnip-lenes into a glafs containing feveral of the male and female flies, I perceived (by the means of a fimple magnifier) that one of the females, after examining attertively the edge of the leaf, and finding a part which appeared to me to have been bitten, unheath. ed her inftruments, infinuated them into the edge of the leaf, and having forced them afunder fo 2 to open a pipe or channel between them, placed her pubes (the fitua tion of which from repeated and almoft inceffant copulations I had been able to ascertain, precifely, and to the lower part of which thefe inftruments feem to be fixed) to the orifice, and having re mained a few feconds in that pe ture, deliberately drew out the in. ftruments (which the tranfpareny of the leaf held against a ftrong light afforded me an opportunity of feeing very plainly) and proceeded to fearch for another convenient place for her purpose. Let the flies may become dif. figured in travelling, it may be prudent to fay, that their wings are four; that their antennæ are c'ubbed, and about one-third of the length of their body, each being compofed of nine joints, namely, two next the head, above which two there is a joint fome. what longer than the reft, and above this fix more joints, fimilar to the two below; that near the point of the tail of the female there is a black fpeck, outwardly tringed with hair; but which, opening longitudinally, appears to be the end of a cafe, containing a delicate point or fting (about one-twentieth of an inch in length) which on a curfory view appears to be a fimple lanceolated inftru. ment, with a ftrong line paffing down the middle, and ferrated at its edges but, on a clofer infpection, and by agitating it ftrongly with the point of a needle, it feparates into three one edged inftruments, hanger-like as to their general form, with a fpiral line wrinkle winding from the with innumerable wrinkles. Hav point to the bafe, making ten ing acquired its full fize, it fixes or twelve revolutions, which line, its hinder parts firmly to the leaf pafling over their edges, gives of a turnip, or any other fub. them fome appearance of being fer- ftance, and breaking its outer coat or flough near the head, crawls out, leaving the skin fixed to the leaf, &c. The under coat, which it now appears in, is of a blueish or lead colour, and the or rated. By the help of thefe inftruments, I apprehend, the female depofits her eggs in the edge of the turnip leaf (or fometimes, perhaps, in The caterpillar has twenty feet (fix of its legs being of confiderable length, the other fourteen very fhort) and in its firft ftage is of a jetty black, fmooth as to a privation of hair, but covered caterpillar caterpillar is evidently diminished in its fize. In every refpect it is the fame animal as before, and continues to feed on the turnips for fome days longer: it then entirely leaves off eating, and becomes covered with a dewy moi. flure, which feems to exfude from it in great abundance, and appearing to be of a glutinous nature, retains any loofe or pliant fubtlance which happens to come in contact with it, and by this means alone feems to form its chryfalis coat. One I find laid up in the fold of a withered turnip leaf (that which I have the honour of inclofing you) was, among fix others, formed by putting common garden mould to them while they were in the exfudatory ftate above defcribed. From the generic characters of the fly I conclude it to be a Tenthredo of Hill; but whether that voluminous author be fufficiently accurate; or whether, from being an almost entire franger to natur 1 hiftory, I may, or may not, fufficiently understand my book, I muft beg leave to fubmit to your fuperior knowledge of the fub ject. I am endeavouring to extend my obfervations on thefe infects, and am making fome experiments concerning them, the refult of which I thould be extremely happy in being permitted to communicate to you; and it may be proper to add here, that I fhould not have taken the liberty of troubling you prematurely with this letter, had I not luckily met with an oppor tunity of procuring fome live flies (which are now become very fcarce; and I flatter myfelf they Vol. XXVI. WE opportunity of this re cent publication, to lay before our readers a brief, hittorical account' of the very interefting difcovery which has of late attracted the notice of the whole philofophical world; and which our fanguine neighbours did not fcruple, at the very first, to dignify with the name of Aerial Navigation. Although the author of this book be known to have warmly efpoufed the party of Montgolfier, in oppofition to that of Charles (for there are parties even concerning balloons), yet his reputation, as a man of learning and ve racity, is fufficiently established, and the facts he here alledges are in general, as we have had opportunities to afcertain by collateral evidence, flated with fufficient accuracy to juftify us in taking him for our guide in this narrative. The Preface contains a fhort furvey of what projects have formerly been fuggefted for the purpofe of floating heavy bodies in the atmosphere; the principal of which are thofe of Lana, a Jefuit of Brefcia, and of Galien, a Dominican of Avignon; both which however were, upon well eftablifhed principles, found by theory F to be impoffible in the execution. Due honour is paid to Mr. Cavallo of London, who, in 1782, feemingly with a view to this difcovery, tried to fill bags of paper and bladders with inflammable air; but failed in his attempts, by the unexpected permeability of paper to inflammable air, and the too great proportional weight of the common fized bladders. Had he then thought of employing gummed filk, or gold-beater's, fkin, he probably would have plucked the very laurels that now adorn the brows of Montgolfier and Charles. what fhort of the weight of the air which its bulk difplaces. On thefe principles, they prepared matters for an experiment, They formed a bag, or balloon, of linen cloth, lined with paper, nearly fpherical, and measuring about 35 feet in diameter; its folid contents were about 22,000 cubic feet, a space nearly equal to that occupied by 1980lb. of common air, of a mean temperature, on the level of the fea. The vapour, which, by conjecture, was about half as light as common air, weighed 990lb. The balloon, tc. gether with a wooden frame fufpended to the bottom, which was to ferve as ballaft, weighed 490lb. whence it appears that the whole muft have been about 500 lb. lighter than an equal bulk of common air. This difference of specific gravity, by which thefe bodies are made to rife, we shall henceforth, without warranting the propriety of the expreffion, call their power of afcenfion. I. The honour of the difcovery is certainly due to the brothers Stephen and Jofeph Montgolfier, proprietors of a confiderable paper manufacture at Annonay, a town in the Vivarais, about thirty-fix miles fouth of Lyons: and their invention is the more to be admired, as it is not the effect of the late difcovery of a permanent elaftic fluid lighter than the common air, but of properties of matter long known, and in the hands of the many acute philofophers of this and of the laft century. They conceived that the effect they looked for might be obtained by confining vapours lighter than com mon air, in an inverted bag, or covering, fufficiently compact to prevent their evaporation, and fo light, that when inflated, its own. weight, added to that of the inclofed vapour, might fall fome The 5th of June, 1783, was fixed on for the difplay of this fingular experiment. The ftates of Vivarais, who were then af fembled at Annonay, were invited to the exhibition. The flaccid bag was fufpended on, a pole 35 feet high; ftraw and chopped wool were burnt under the opening at the bottom; the vapour, or rather fmoke, foon inflated the bag, fo as to diftend it in all its parts; and, on a fudden, this immenfe The impoffibility of Lana's project was demonftrated by Hook; fee his Philofophical Collections, No. I. p. 28. And fince by Leibnitz. Galien's never needed any confutation. + All the measures here given are French. The French foot is to the English at 144 to 135; a French toife is fix French feet, or, fix and threeeighths English feet. mafs |