MISCELLANEOUS PAPERS. LETTERS on the BREEDING and TREATMENT of SILK WORMS. [From the TRANSACTIONS of the Society for the Encouragement of Arts, Manufactures, and Commerce.] February 1, 1785, the Silver Medal was voted to Mifs HENRIETTA RHODES, of Cann Hall, near Bridgnorth, for her fedulous Attention to and judicious Obfervations on the breeding and treating of SILK WORMS, as communicated in the firit of the following Leiters; and the Thanks of the Society were given to her for her fecond Letter on the fame Subject, in which is contained an Account of the Succefs of her Experiments during the following Summer. 66 'N addreffing this letter to you with the inclofed hank of filk, I believe I deviate from the mode which your institution prefcribes, to those who become claimants for the honorary rewards which are fo nobly diftributed to genius and induftry; but my attempts have fallen fo fhort of what is required by the fociety, that I dare not appear before them under any of thofe forms which would indicate my pretenfions to be unequivoca': fuch however is the idea I have formed of their liberal propenfity to patronize the efforts of preferving ingenuity and laudable ambition, that if I fhall be found to have fucceeded better than any one elfe; if the fpecimen of filk I produce, is (and I have been fo told by many good judges) fuperior to any that has yet been manufactured in England, and equal to that which comes from Italy: and if I can prove that it is impoffible for fo large a quantity as five pounds to be procured in one year, until planta ions of mulberry trees have actually been made, 1 Batter my felf that I fhall not remain undiftinguished. "I will begin from the period in which I first took to feed filk worms, as it will ferve to fhew their prodigious and rapid increafe. In the fummer of the year 1782, a dozen and half of filk worms were fent me by a friend who relided at a diftance; I was then totally ignorant of the method of treating them, but I preferved them in health, and they produced me a great number of eggs. "In the May following, (1783), I found my stock increafed to about thirteen hundred, and I was fo fortunate as to lofe very few during the whole time of feeding; for I had twelve hundred and feventy very fine cones, and they produced me near four ounces of filk. I preferved all the eggs from thefe, and on the 12th of laft May, placed them in the fun, they were hatched in incredible numbers; and by the most accurate calculation, I was mirefs of more than ten thousand; I fed them with lettuce leaves, for the first week, and then from three or four mulberry trees, which grew in fome adjacent gardens. However, as they grew larger, they became fo extremely extremely voracious, that I felt the most mortifying apprehenfions left a famine fhould enfue; and my compaffion for the induftrious little animals who depended on me folely for their daily food and fupport, was fo abundantly excited, that the prefervation of their lives became an interesting object independent of the advantages I had propofed to myself. I fought after mulberry trees with an anxiety I cannot describe, and the discovery of a new one was a real acquifition. At length my resources were augmented to the number of twelve trees, though fome of them were at the distance of ten miles from me. To these the kindness of many friends enabled me to fend every day, and the frequency of my vifis, were vifibly difplayed on all the trees; of the truth of this you will judge, fir, when I inform you that a bufhel of leaves crammed in as clofe as poffible, would frequently be infufficient to fupport them one day. Towards the latter end of June, they had attained their full growth, when an unexpected circumftance, checked my ambitious hopes, (for until then I had certainly entertained the extravagant idea that I might poffibly gain the golden fleece, which would intitle me to the envied prize) and deprived me of thoufands of my infects. You will perhaps recollect a moft awful and tremendous thunder florm, which happened about this period, in the night, and which spread a general alarm throughout England. On visiting my manufactory early the next morning, I found that the lihtning had ftruck feveral of the pans; for I cannot believe that the noife of the thunder could occa tion fuch appearances. A large pan immediately oppofite to the window, containing about five hundred filk worms, was full of a liquor as yellow as gold, and all the little anima's who had been its inhabitants, were dead, and as ap parently fcorched up, as if they had undergone the operation of fire; while others of the pans, had been only partially affected. moved all the dead, but my misfortune did not end there, for three fucceeding days prefented me with fuch numbers who had equally felt the baneful effects of the lightning, that my immenfe ftock was reduced to two thousand eight hundred and ninety three: thefe were exceedingly fine and healthy, and they began fpinning on the 7th of July. During all this time, they had had no other attendant than myfelf, except when the pans were to be cleaned, which was about once a week, and in that office I was affifted by a fervant. I fed them three times a day with leaves which had been gathered in the morning, and they took up fo fmall a portion of my time, that neither my amufements, or any other avocations, were interrupted by it. "By means of a finall and very fimple machine, which I invented for the purpofe of winding the filk, I was enabled to get through that talk very expeditiously. I felected two hundred and fifty of the largest cones, and from them I wound the fkean which I have fent you; its weight is three quarters of an ounce and one drachm: however, upon an average, I find that three hundred and fixty cones produce an ounce; for from the two thoufand eight hundred and ninetythree, I had exactly half a pound of filk: the whole is precifely of the fame colour, texture, and height of gum with the inclosed. Of the wafte filk with which the cones are furrounded, I had fomewhat more than a quarter of a pound, and I fent it foine months ago ago to Nottingham, to be carded and wove into ftóckings. It was my defign to have fent thofe flockings alfo, for the infpection of the fociety, but the manufacturer has not yet returned them to me. which threatened me, I tried most of the different leaves to be found in a large kitchen garden, but the filk worm would eat none, except lettuce and fpinnage; and they perifh even on those in a very short time, owing, as I imagine, to their moisture and coldness. "I am determined to perfevere until I have procured a fufficient quantity to make a piece of filk; The criterion to judge of the but the difficulty which attends goodness of filk is, I have been the meeting with food, and the told, by the height of the gum ; unpleafant circumftance of being that mine more than vies with the fo very troublesome to one's friends, Italian filk, in this refpect I thus renders it neceffary for me to pro- account for in their climate, the ceed by a flower progrefs than I chryfalis foon comes to life, and it had hoped for. is neceffary to deffroy them, left by eating their way out, they should injure the filk; and to effect this, they are placed in heated ovens: in ours, where every progreffion is flower, there is fufficient time to wind off the filk, without killing the chryfalis. I frequently wound the cones out of boiling water, placing them afterwards on dry paper, and always found that the chryfalis came to life again, at its proper time. "From the recital I have given, it will appear very obvious, that a number not less than thirty thousand must be fed to obtain five pounds of filk; and that the leaves of twelve large mulberry trees, (allowing that they were not ab. folutely ftripped) were fcarcely found adequate to the fupport of ten thousand. "The eafe and fuccefs with which I managed my manufactory, will, I think, make it equally ap-' parent, that if it be pollible by any means to ftimulate the fpirit of making mulberry plantations, that the whole difficulty is overcome. "The expence of erecting a place for them would be very trifling, and from the little trouble I myself experienced in the management of my ten thousand, I am of opinion that two perfons would be fufficient to take care of a whole manufactory, until they begin to fpin. The period they lived with me was about fix weeks. The calamity mine fuffered from lightning, is not to be adduced against me, that was certainly no common occurrence; and if it were, might be guarded againft, as mine were in an expofed fituation. "Amidit the fcarcity of food, "If therefore the chryfalis could bear fo great a degree of heat as boiling water, it is obvious that the warmth of the ovens, and the length of time neceffary to keep them there, muit greatly injure the strength and gloffy hue of the filk. But this is not all, for in Italy they fuffer the moth to eat its way out of the largest cones, in order to have eggs from the most healthy, and thereby lofe all the filk in thofe cones. Here the filk may be gathered as well as the moth preserved; and thus do we poffess two ftriking advantages, which amply compenfate for the lofs of many others. Upon the whole I am de. cidedly of opinion, that this great article of commerce, which use and luxury have rendered fo effential to our comforts and conveniencies, and “SIR, "THE marks of approbation which the fociety honoured me with last year, together with your polite wishes to hear from me again, have determined me to communicate the fuccefs which has attended my management of filk worms this fummer. "I think I mentioned in my laft letter that the difficulties I had encountered in procuring mulberry leaves, had fo far checked the ardour of my ambition, that I should greatly limit the extent of my manufactory another feafon; I accordingly preferved only one fheet of writing paper covered with eggs; and in order that the worms might have the advantage of the hotteft fummer months, thefe eggs were not expofed to the fun until the morning of the first of June; before night, fome hundreds were hatched, and in a day or two the whole made their appearance. Having convinced myself by repeated experiments, that the lettuce was the only food which could be relied upon next to the mulberry, I had caufed fome large beds to be care fully cultivated; and it now remained for me to make trial how long they would fubfift upon thefe without injury to their growth, or the produce and texture of the filk; they were fo extremely fine and healthy, that I fed them folely with lettuces until the 24th of June, a lunar month within four days, and more than double the time they used to be kept from the leaves of the mulberry tree. "In less than a week after their change of food, they began to fpin, and I had the pleafure to observe that the cones were as fine and firm as any I ever had. "By the latter end of July, the whole bufinefs was completed, and I had wound exactly four thou fand cones, which produced me eleven ounces of filk, precifely the fame as the fpecimen you have seen. I am tempted to entertain very fanguine hopes from the difcovery that the filk worm will fubfitt fo long a period of it's little life, on an indigenous plant fo eatly procured; the more efpecially fo, as I did not lofe a dozen during the whole time of their feeding, and can demonftrate that the cones were not inferior in fize and weight to thofe which have been manufactured in Italy. "Mrs. Williams, in the account fhe has given of her management of filk worms, (fee the fecond vol. of the Tranfactions, page 153.) afferts that two hundred and forty four, produced near an ounce and half of filk. Upon an average I have collected no more than one ounce from three hundred and fixty of mine; but this apparently material difference between us, will be found to exift only in the ftatement of facts. "Conceiving that the premiums offered by the fociety, extended merely to that filk which may be manufactured without carding, I held it incompatible with my ideas of truth and candour, to bring the wale in the fpring; and neither could waste or carding filk, into the account,, otherwife I fhould at all they nor the leaves of the blacktimes have been able to double my berry, even then, be procured in quantity. For the loose filk which fufficient quantities to ferve a ma you must trip from the cones, nufactory. Of the young leaves before you begin to wind, together of the elm, I myfelf made trial, to with fome that will remain round the deftruction of nine worms out them at the last, notwithstanding of twelve, which I gave them to. the utmost care, is nearly one third The remaining three I refcued from more than that which I have un- the fame fate, by giving them the derstood to come under the deno- mulberry leaf; but they never remination of merchantable filk; and covered their strength futficiently thus this year I might have boafted to form a cone. of twenty-five ounces instead of eleven, if, like Mrs. Williams, I had included the filk for carding. "In a treatise which lately fell in my way, addreffed to the trustees for establishing a filk manufactory in Georgia, the author, who feems perfectly well informed on the fubject, tells us that the cones in general are found to contain three hundred yards of filk, which weighs no more than two grains. Happy to meet with a piece of information which would enable me to afcertain the degree of perfection I had brought the filk worm to, I meafured the filk from one cone, with the most critical, exactnefs, and found it contained four hundred and four yards, which when dry weighed three grains; and this was from one of the worms which fed only a week upon mulberry leaves. I muft, however, acknowledge that although this cone exceeded the given quantity in weight and meafure, that all were not equally fine, and that I purfued the thread through all its intricacies, with a molt perfevering patience. "Mrs. Williams's obfervations on the various kinds of leaves they will eat, admitting their truth, can never be of the leaft utility, unlefs to gratify the curiofity of the fpeculative philofopher. She talks of gathering cowflip leaves in October, but they vegetate luxuriantly only "I alfo adopted the ingenious hint of the honourable Daines Barrington, and collected thofe kinds of leaves which were fimilar to the mulberry, in taste and appea rance; fuch as the nut, currant, lime, kidney beans, ftrawberry, chefnut, rafberry, &c. &c. but none of thefe would do. The cabbage leaf, (of which I was enduced to make trial, because it is made choice of by our common caterpillar) was preferred to either of thefe, though fparingly eaten of; and I had no with to try the effect of their continuance at this food, as the fmell would render it unfit for a large manufactory. A female friend of mine, who had kept filk worms, many years ago, affured me that they devoured fh leaves with great avidity; and a gentlema of my acquaintance, likewife told me that his fifter ufed to give them vine leaves. The latter, mine would not venture to begin upon, and of the former, they were fa tiated at one meal. "Mr. Barrington fuggefts that it might poffibly be difcovered what leaf the ik worm would live beft upos, if we were to ob ferve what infect made the mul berry its fuccedaneum; it has therefore escaped the notice of that learned inveftigator into the phænomena of nature, that no other infect whatever, will feed upon the mulberry |