The Author of this article has long been known as an improver of operative chemistry, and we are glad to find that he obliges the Public with his useful difcoveries.

POLITE ARTS.

The firft Paper on this fubject is, A Letter from Mifs Greenland, on the ancient Grecian Method of painting in Wax. As the account is short, we fhall give it to our Readers in the Authorefs's own words:

Take an ounce of white wax, and the fame weight of gum maftick powdered. Put the wax in a glazed earthen veffel, over a flow fire, and when it is quite diffolved, ftrew in the maftick, a little at a time, until the whole quantity of gum is perfectly melted and incorporated; then throw the pafte into cold water, and when it is hard, take it out of the water, wipe it dry, and beat it in one of Mr. Wedgewood's mortars, obferving to pound it firft in a linen cloth, t abforb fome drops of water that will remain in the pafte, and would prevent the poffibility of reducing it to a powder, which must be fa fine as to pass through a thick gauze. It fhould be pounded in a cold place, and but a little at a time, as, after long beating, the friction will in a degree foften the wax and gum, and instead of their becoming a powder, they will return to paste.

Make fome ftrong gum-arabic water, and when you paint, take fome of the powder and fome colour, and mix them together with the gum water. Light colours require but a fmall quantity of the powder, but more of it must be put in proportion to the body and darkness of the colours; and to black there fhould be almoft as much powder as colour.

Having mixed the colours, and no more than can be used before they grow dry, paint with fair water, as is practifed in painting with water colours, a ground on the wood being firft painted of fome proper colour, prepared in the fame manner as is defcribed for the picture; walnut-tree and oak are the forts of wood commonly made ufe of in Italy for this purpofe. The painting fhould be very highly finished, otherwife, when varnished, the tints will not appear united.

When the painting is quite dry, with rather a hard brofh, paffing it one way, varnish it with white wax, which is put into an earthen veffel, and kept melted over a very flow fire till the picture is varnished, taking great care that the wax does not boil. Afterwards hold the picture before the fire, near enough to melt the wax, but not make it run; and when the varnish is entirely cold and hard, rub it gently with a linen cloth. Should the varnish blifter, warm the picture again very flowly, and the bubbles will fubfide. When the picture is dirty it need only be washed with cold water.'

Mifs Greenland has prefented to the Society fome pictures which the had painted according to the foregoing directions; and he has been rewarded by the premium of the Gold Pallet.

The next Paper is on the important fubject of Education. The scheme to which it relates, viz. The beltowing a Premium on fub Masters as would teach not less than four Scholars to Speak

114

Speak Latin in common conversation, correctly and fluently, we for merly communicated to our Readers, when we reviewed the earlier volumes of thefe Transactions.

On the 19th of December 1786, the Society beftowed a gold medal on the Mafter of a fchool [Dr. James Egan, of Greenwich], and a filver one on each of five pupils who stood candidates for the proffered reward. On these we beftow our mite of praife, from the fuppofition that the examination of these young ftudents was performed by men of acknowledged learning, and particularly eminent as judges of correct Latinity. Such men we confefs are not to be frequently found; but fuch there are, and we are perfuaded that their liberality of mind, joined with a defire of encouraging the purfuit of ancient literature, would induce them to accept with eagerness any invitation to fuch a trial of youthful abilities. We are only told, however, that the Pupils were examined by the COMMITTEE.

It is true, that many people, after feveral years unremitting ftudy, write Latin ;-and that many more read Latin. This we do not deny, but we must affirm, that we have rarely, very rarely, met with any perfon who could speak Latin in common converfation, correctly and fluently: in this we are convinced, from the Paper before us, that we have been unfortunate. Each of the candidates tranflated, separately, a Paper, written for the purpofe, and answered, fatisfactorily, in Latin, fuch questions as were afked. We with these questions had been printed, and with them their answers, as it would have convinced the Public, and the Members of the Society who were not present at the examination, that the Committee acted with propriety, in adjudging the rewards.

Three months after this decifion, at the inftigation of the pupils, a letter was written by the Mafler to the Secretary of the Society, to return their grateful thanks for the honours which they had received. This letter contains alfo the thanks of the Mafter, who declares his gratitude to the Committee, for affording the candidates an opportunity of difplaying their abilities. Dr. Egan defcribes the method, which he ufes in his school, of teaching his pupils to speak and write Latin correctly and fluently. The whole of his plan does not meet our approbation; but we fhall fufpend our animadverfions on it. We muft, bowever, remind the Society, that it feems to have interfered in matters foreign to its plan. As a Society of Arts it is refpectable, and has been of much real fervice to the nation, by promoting and encouraging improvements in agriculture, manufactures, &c.; but Omnia non poffumus omnes; the Society in

* Writing Latin was also mentioned as a requifite for obtaining the premium.

ftituted

ftituted for the encouragement of Arts is not, nor cannot be

expected to be, a Society for the encouragement of Literature. B--y.

The next Paper gives us The Defcription of a Machine to teach Mufic to People deprived of Sight, and to enable them to preserve their Compofition, in the Act of compofing, without the Affiflance of a Copyift. By Mr. Griffith James Cheese.

This contrivance confifts in expreffing the written mufic, by pins, of various forms, ftuck in a cushion. The cushion is stuffed on a frame; and on the top of it, five ftrings of packthread are fewed, parallel to each other, the whole length of the cushion; thefe ftrings reprefent the lines which compofe the ftave; they are made of coarfe packthread; and those which reprefent the Ledger, or occafional lines, drawn through the heads of the notes, where the mufic exceeds the compafs of the established ftave, are made of fmaller twine, and, like the other five, are extended the whole length of the cushion. To write harpsichordmufic, the cushion may be of any length, and about five or fix inches wide; the ftrings are fewed in the following order, beginning from the bottom: first, four small threads, which correfpond with the notes in the base of the inftrument ff, rr, cc, ee; next five large ones for the ftave, which correfpond with the notes in the inftrument g, b, d, f, r; one fmall one, which reprefents the occafional line between the bafe and treble, or middle; five large ones for the treble flave, which make the notes e, g, b, d, f; three fmall ones, which reprefent the ledger lines when the mufic goes in alt; thefe provide for the notes a in alt, e in alt, and e in alt, in the space above which, next the edge of the cushion, the f in alt is wrote when it is wanting, which completes the compafs of the inftrument. Mr. Cheese then describes the fize and form of the cushion for finging or playing on fingle inftruments, fuch as violins, &c. This cufhion is only half the width of the former; it has on it only one stave, and that in the following order: two fmall lines at the bottom, five large ones in the middle, and three fmall ones at the top; it must be obferved, that neither of the outfide lines fhould be fewed close to the edge of the cushion, as notes may be fuppofed to be both above and below. At each end of each cushion are ftaples, fo that any number of cufhions may be combined together by running a rod through the ftaples.

The characters ufed to write on this machine are pins, fome with one, two, three, or more heads; others without heads, others with the heads flatted and flit, others with the heads bent in various forms, fo that each may reprefent a femibreve, minim, crotchet, quaver, &c. &c. with the refpective refts, and all the different characters that are requifite.

We hope that the above defcription, which is the best we sould give without the plates, will convey to our Readers fome

adequate

adequate idea of this ingenious contrivance, which will not only teach blind perfons mufic, but, by calling the characters, letters, a blind man may be enabled to write, and convey his fentiments to his friend, without the affiftance of a fecretary, or to read letters fent to him. It is eafy alfo to apply this machine to arithmetic and algebra; and, with fome little alterations, to geometry.

MECHANICS.

Defcription of the Statical Hydraulic Engine, invented by the late Mr. William Westgarth of Colecleugh. By J. Smeaton, F. R.S. This machine is conftructed on the principle that a longer coJumn of water will outweigh a fhorter. We wish it were in our power to give our Readers a defcription of the curious invention here ufed by Mr. Weftgarth, but the complications of valves, &c. neceffary to produce the alternate librating motion of the pumps, cannot be explained without figures.

In our excurfions in the north, about 15 years fince, we remember to have seen one of thefe machines in the lead mines of the late Sir Walter Blackett, which worked well, and, at a very fmall expence, perfectly drained the mine.

MANUFACTURES.

In our Review, vol. lxxv. p. 422, et feq. we gave a circumfantial account of the labours of Mifs Henrietta Rhodes, in ber filk manufactory at Cann Hall, in Shropshire. By a Paper which is inferted in the volume before us, we are forry to find that the has experienced fome difappointments in the profecution of her ufeful fcheme; but she does not think herself totally unfortunate, fince thofe very disappointments may supply the most useful hints to others, and, however paradoxical it may appear, they are fo many new proofs of the practicability of her plan.

About the beginning of July 1786, Mifs Rhodes had several thoufand healthy worms, but, juft at the period of their beginning to fpin, a chilling north-eaft wind fet in, and the baneful effects of the uncommon cold were feverely felt by her little family. All thofe which were ready to fpin became of an icy coldnefs; they made fome feeble efforts to eject the thread, but in vain, for they fhrunk into the chryfalis ftate without being able to form the web which inclofes the cone. On examination, the found that the glutinous matter, which forms the filk, was become fo congealed by the cold, that it refembled a strong tendon, both in appearance and tenacity. Thoufands died daily. It was fufficiently obvious that fires would remedy the evil; but the worms being fituated over a large range of warehouses, rendered that expedient impracticable; and to remove fuch numbers into the house was impoffible. They were, however, foon fufficiently reduced, fo that the removal of them was easily accomplished;

and

and with the help of conftant fires the worms recovered their ufual health, arrived at maturity, and purfued their induftrious Occupations with alacrity.

Hence it appears, that cold, though it impedes their growth, does not effentially hurt the worms until they arrive at the state for fpinning; and that then a certain degree of heat is requifite, to render the filk fufficiently fluid to be ejected with ease.

6

This difappointment, however, has not difcouraged the lady; for I have refolved,' fays fhe, not to relinquish my defign till I have obtained the quantity of filk neceffary for a drefs.' p. 146. We heartily with her fuccefs.

Though that was originally her fole motive in cultivating filk worms, yet the bas fufficiently eftablished the following facts:

Firft, That the management of the filk worm is by no means difficult; the principal objection having been obviated, by the difcovery that they may be fupported fo long a time on an indigenous plant, which may be procured in all fituations.

Secondly, That our climate fupplies a fufficient degree of warmth to bring the filk to the highest degree of perfection, unless in very extraordinary seasons, which may be guarded against by the conftruction of fire-places.

Thirdly, That the profits, which arife from the manufacturing of filk, are immenfely advantageous; one fourth part of the price of the filk being adjudged enough to defray the whole expences.'

The next article, on the fame fubject, is a letter from the Rev. Mr. Swayne, of Puckle-church, near Briftol. This gentleman objects to Mifs Rhodes's method of fubftituting lettuce for mulberry leaves, as food for the worms. He thinks the extent of land neceffary for the growth of fuch a quantity of lettuces as would be fufficient for the confumption of any confiderable number of worms, muft render every attempt to raise filk upon that plan ineffectual. He feems not rightly to comprehend Mifs Rhodes's intentions; the fubftitutes lettuce leaves at a time when mulberry leaves cannot be procured; and by bringing forward the worms to fpin at different times (or rather procuring a feries of (pinning periods), the filk harveft, if we may use the expreffion, may be protracted for a great length of time, and confequently the hurry and expence of reaping a large and fudden crop of filk is avoided. See this fully explained in our former account of Mits Rhodes's method, in Rev. vol. lxxv. p. 424, &c.

Mr. Swayne thinks any fubftitute for the mulberry unneceffary, yet he fays, As a farther direction to a research of this kind [f finding a fubftitute for mulberry] the obfervation of botanists may be adduced, that plants of the fame natural clafs and order have a near resemblance in their virtues and qualities. This clue would lead us only to a few plants of the native growth of

* See Rev. above quoted.

B