156 ANCIENT VASES. with a draw knife, or other instrument, perfectly smooth, which must be particularly attended to: then lay on the plaster, about one-eighth of an inch thick, all over the part where the wood or bark has been so cut away, finishing off the edges as thin as possible. Then take a quantity of dry powder of wood-ashes, mixed with a sixth part of the same quantity of the ashes of burnt bones; put it into a tin box, with holes in the top, and shake the powder on the surface of the plaster, till the whole be covered over with it, letting it remain for half an hour to absorb the moisture: then apply more powder, rubbing it gently with the hand, and repeating the application of the powder, till the whole plaster becomes a dry, smooth surface. "All trees cut down near the ground, should have the surface made quite smooth, rounding it off in a sinall degree, as before mentioned; and the dry powder directed to be used afterwards, should have an equal quantity of powder of alabaster mixed with it, in order the better to resist the dripping of trees and heavy rains. "If any of the composition be left for a future occasion, it should be kept in a tub, or other vessel, and urine of any kind poured on it, so as to cover the surface, otherwise the atmosphere will greatly hurt the efficacy of the application. Where lime-rubbish of old buildings cannot be easily got, take powdered chalk, or common lime, after having been slaked a month at least. "As the growth of the tree will gradually affect the plaster, by raising up its edges next the bark, care should be taken, where that happens, to rub it over with the finger when occasion may require (which is best done when moistened by rain), that the plaster may be kept whole, to prevent the air and wet from penetrating into the wound," ANCIENT VASES. (Continued from page 139, No. 149.) Although the black coating produced in this manner upon the surface of ear then vessels, agrees in many of its qualities with the varnish of the antique Grecian vases, and it is not improbable, that a similar substance, and a similar mode of painting, was used in their manufacture; yet the varnish prepared in the manner above described, differs from the ancient varnish in this respect, that it does not resist a very great degree of heat; nor have I as yet succeeded in my efforts to discover, by what means the faculty of sustaining the power of an intense heat could be given to varnish prepared of asphaltum. However, it is evidently not impossible, that time may have done something in this respect, which art could not produce. But, It is well known, that asphaltum and naphtha were among the substances known to the ancients, and that they were applied by them to various purposes. Pliny, in fact, relates, that inscriptions made with Jet (Gagates) upon earthen-ware, are not effaced. from what we learn with regard to this Gagates of Pliny, it is to be inferred, that it was not the Jet of modern times, but asphaltum; which renders it probable, that the art of making a coating for earthen-vessels of that substance nish and paintings, indeed, which occur in the sepulchral vases of the Greeks, do not seem to have been applied by the Romans to earthen-ware manufactures; for no traces of them occur among the numerous remains of Roman pottery. A covering, however, in some respects similar to it, but consisting of vegetable pitch, was used by the Romans in their wine vessels, the preparation of which is accurately described by Columella. I do not doubt, that a varnish made from asphaltum in the manner above described, and the mode of painting founded upon it, to which the name of Enamelling is applied, might be used with advantage in modern pottery, as for ornamenting vessels, covering tiles, &c. was known to the ancients. The var Besides the black varnish, some other colours are seen in Grecian and Etruscan sepulchral vases; for example, white, yellowish white, red, brown, rarely bluish-green or livid.§ In the *Natur. Hist. lib. xxxvi. cap. 34. + Consult. Brocchi, sulle Vernici usate dagli Antichi. Bibl. Ital. t. vi. p. 459, 463. De Re Rustica. Lib. xii. cap. 18. § Hirt, in Boetticher's Griech Vasengemälden. Bd. 1, Heft. 3. p. 27. Millingen, Peint. Ant. p. 5. GEOMETRICAL PROBLEM AND SOLUTION. vases whose paintings are made of the varnish itself, particular parts only of the paintings consist of these colours; for example, leaves, flowers, architectural ornaments, the drapery of figures, the wings of winged figures, horses, chariots, &c. In other vases, which are evidently covered with black varnish, certain ornaments are sometimes laid in upon it with other colours, especially white. The nature of these pigments is as follows: 1. They are, without exception, opaque, and belong to the paints called in German Deckfarben. 2. They seem prepared either from earth or metallic oxides; for example, the white pigments from argil; the red from oxide of iron; the brown from oxide of iron mixed with oxide of manga.nese. 3. They are not vitreous, but have an earthy aspect. 4. They are not intimately united with the baked-clay; they fall off, and may easily be abraded; they are partly dissolved in acids. 5. They are usually laid upon the black, varnish, which appears evident enough when particles of the paint have fallen off, or are abraded, by which the black varnish is discovered. From these properties, it may be inferred, that antique painted vases have not been baked in the same manner as our earthen-ware is, along with the pigments, but have had the pigments applied to them after being baked.+ We shall now, in the second place, speak of the mechanical method, in which the varnish and paintings have been applied. All that I have observed with regard to this matter, during a dili gent examination of Grecian and Etruscan vases, as well as all that has already been observed by others, agrees well with the opinion expressed above, regarding the composition of the varnish. Some antiquarians have thought, that the paintings of the Grecian vases have been perfected by the assistance of the moulds to which our workmen gave the name of Patrones. Others have supposed, not that the whole paintings, but the ornaments, have been made in this way. I cannot, however, give my as 157 sent to thèse opinions. If the figures or ornaments had been perfected by the aid of moulds, vases would undoubtedly be sometimes found in the same place, with the same paintings. But although similar representations are not unfrequently seen in different vases, there have never, in so far at least as I know, been found two vases, whose paintings correspond in every respect, which has already been remarked by Grivaud.* If the ornaments, which might have been made by means of moulds more easily than the more diversified and complex figures, be attentively examined, certain irregularities and slight blemishes will often be found, which would undoubtedly have been avoided, if moulds had been applied in the painting of vases. (To be concluded in our next.) GEOMETRICAL PROBLEM AND SOLUTION. 66 SIR,-AS of the readers of many portunity of perusing Taylor's “ Eleyour Magazine may not have an opments of Thought," the following extract from that publication, may not be altogether unworthy of your notice. The author is endeavouring to prove, that "many of the first principles of science seem to imply a direct contradiction: they are, apparently, impossible, and yet true; so that, while they demand assent, they baffle the understanding." And readers will be astonished to find that I doubt not that very many of your they must believe that, Two points or lines may continue to approach each other for ever, and yet never meet! But, however startling the proposition may appear at the first reading, it is not the less true,`and, with our author, we must sooner or later acknowledge, that we are often obliged, by unquestionable evidence, to assent to propositions which not only surpass our power of comprehension, but which seem directly to contradict the plainest truths.' Your's, obediently, EDWARD B. PALMER. Mutford, Suffolk, May 21st, 1826. Two points or lines may continue to approach each other for 66 Jorio Sul Met. d. Ant. nel dipingère Vasi, p. 9. 158 PROPERTIES OF NUMBER NINE. ever, and yet never meet;" which both divisible by 9; conséquently, may be proved thus The lines A B, C D, may be imagined to be continued infinitely; let the line A B, be divided into equal parts.-1, 2, 3, 4, &c. so that these points continued on an infinite line, shall be infinite; let a point E, be taken in the line C D, and lines drawn from it to the divisions in the line A B, as E 1, E 2, E3, &c. It is evident that the line E 3, is nearer to the line CD than the line E 2, and that the line E 4, is nearer to it than the line E 3. Now these lines, from the point E, may continue to be drawn to the successive division in the line A B, ad infinitum; and every succeeding line will be nearer to the line C D, than the preceding line; and yet no line running from one parallel line to another, can ever meet or coincide with either of them; or, in other words, the lines from the lower to the upper line, may continue for ever to approach the lower, but can never meet it."Page 95. To the Editor of the Mechanics' \Magazine. Sir, The properties of the number 9 are not of such infinite service to the man of figures, as J. Key Pringle states; yet, while those properties are given, their utility should at the same time be pointed out. For example, since the sum of the digits or significant figures in the products is either 9 or a multiple of 9, if the numbers of a fraction be either a 9 or a multiple of 9, they are divisible by 9, which is shewing the use of the above property. 720 Example. Reduce to its lowest terms. 3249 The sum of the digits in 720 is 9, and 720 3249 80 = 301 9 times any multiplicand being 10 times minus once, the same, and 99 times equal to 100 times, minus once, the same, &c. To multiply, therefore, by any number of 9's, annex a cypher for each 9 in the multiplier, from which subtract the multiplicand. To find the product of any number from 12 to 20, by 9 mentally.-The units of the first product (as in the multiplication by any other number as well as 9) is the units place of the required product,and the tens place is thesum of the tens and hundreds, of the required product, and as in this case, is always the hundreds place, the tens must therefore be lessened by 1: thus, 9 times 19 171; for 9 times 9: that is, I for the unit's place, and 8 being the sum of the other two places, 1, 7, and 1, are therefore the digits of the product, which may be found in one-third of the time that the reader will be employed in reading these lines. 81; The following is a curious property of 9. 9 times 98765432 888888888; and the division of SS8888888, is 98765432. For the division by any number of 9's see Russell's Philosophy of Arithmetic, just published by Souter. Note. I have lately been endea vouring to find easy methods for reducing fractions to their lowest terms by inspection, and have met with little or no difficulty in knowing whether the numbers of a fraction be divisible by 2, 3, 4, 5, 6, 8, 9, 10, 11, and other higher numbers: yet I cannot tell how the terms of a fraction are to be inspected for their division by 7. If any of your arithmetical readers will assist me in this, I shall feel obliged. I am, Sir, 32 49 is 18; they are, therefore, April 25th, 1826. CLYDE, EXPERIMENTS IN ELECTRICITY. CALCULATING BOY. Mr. Editor,-In No. 137, page 398, of your interesting miscellany, mention is made of another calculating boy, who is about to exhibit his powers before the public. With respect to the first specimen of his skill, with which you have favoured us, I suspect an answer to another question has been given; the true answer will be found to be 455520. A SUBSCRIBer. ON SOUNDS. In answer to Philobotanicus, No. 133, page 355, I believe it to be an established opinion, that sound is conveyed through the air in undulations, similar to those produced by the falling of a stone into water, with this exception, that in water the undulations move on a plain surface, whereas in the air they move in a spherical form. Concluding, then, that in the day-time innumerable undulations take place, the passage of one undulation must be considerably retarded by the undulations of other sounds. In the night-time, when the greater portion of noises have ceased, sound is conveyed to a far greater distance; partly owing to the undulations being less retarded by other undulations; in part, because the atmosphere is colder, which is much more favourable to the transmission of sound; and partly, because there is a greater degree of moisture in the air, which moisture acts as a very good conductor. Franklin states, that at a distance of two miles he heard the sound produced by striking two stones under water. I am, &c. X. OP AGE. EVERY living thing has its beginning and ending, and undergoes innumerable changes. Thus we see that infancy is weak and feeble; but youth is comely, flourishing, and luxuriant. Manhood is plump, strong, and full of stature; but old age 159 droops, becomes weak, languid, and dissolution. Plants are subjected to dry, the sad presages of approaching the same vicissitudes, and go through the same stages. In their infant, or very useful state, they are small and weak, destitute of flowers and fruit; when more advanced, they wanton in beautiful and shining colours, being the most agreeable, and, as it were, in the joyous spring of life; in summer, being then more plump, firm, and strong, but less splendid, they bear fruit in autumn, or old age, they droop, grow dry, and wither, returning to dust from whence they came. The ivy, in its first or tender state, has spear-shaped leaves, and bears neither flowers nor fruit. This is that variety, which Bauhine calls Hedera humi ripens," Ivy creeping on the ground." The same plant, when more advanced, bears fine lobed leaves, climbs on trees and walls, and is barren. This variety, Bauhine calls Hedera major sterilis, the "Greater barren ivy." In the next, or more mature state, it sends forth three-lobed leaves, and, leaving its props and supporters, it rises by its own strength, and puts on the ap pearance of a pretty tall tree, being loaded with flowers and fruit. This is the Hedera arborea, or "Free ivy." But when old, it puts forth egg-shaped leaves, without lobes. This is the Hedera poetica, or "Poet's ivy." Daily experience abundantly shows, that all plants undergo a variety of changes. From the seed spring up tender shoots, which at first resemble small shrubs; these, by degrees, acquire a firm trunk, and bear flowers and fruit; after this, the branches flag, and are covered, as well as the trunk, with moss; first one branch decaying, and then another, till the whole tree moulders away, and the place thereof knoweth it no more, LINN. EXPERIMENTS IN ELECTRICITY. SIR,-In the course of pursuing some experiments in Electricity, lately, I wanted to communicate to a friend at a distance the results, and the exact degree of electricity 160 AGRICULTURAL QUERIES, &c. which my machine was capable of exciting; just at this time a thought struck me, which, if it would effect no other end, would at least this. I will describe as briefly as I can my idea. If a wire rod be exactly balanced on an upright pillar, with a brass ball at each end, and one end of the rod be graduated, a weight being attached to that end, and regulated at different distances, you may ascertain the exact weight which your electrical influence is capable of overcoming, in raising the ball of the graduated end, by approximating it to within the influence of the ball of the conductor. If you should think the above worth insertion in your excellent Publication, You will oblige, Sir, Your obedient servant, AMICUS. ON DRESSING POTATOES. Where these useful roots are boiled for the purpose of feeding swine, or other animals, they should be put into bags or sacks, leaving room for them to swell, and when sufficiently boiled, the sacks should be taken out and left to drain, for the water becomes so strongly impregnated by the poisonous properties of the roots, as to be highly detrimental to animals in general. This will account for the disappointment of those persons, who feed their pigs with potatoes mashed with the water in which they have been boiled. When prepared agreeably to the above direction, potatoes become a most beneficial food for pigs, but they are by far less nutritious in the raw state, for the poisonous qualities not being drawn out by boiling, it counteracts the benefit of the farinaceous qualities of the root. AGRICULTURAL QUERIES. SIR, Not agreeing with your Correspondent Agricola, in your 132d Number, on the propriety of using Machines in Agriculture, I take the liberty of asking, through the medium of your Miscellany, the following questions: Would it not be possible to draw our ploughs by steam-engines? And where is Mr. Michael Barry's machine for digging potatoes to be seen at work? In your 116th Number, Mr. Ogle has very disinterestedly presented the public with the plan of a reapingmachine. Would he, or the Messrs. Brown mentioned by him, deliver a machine competent to do the work he has stated, under this proviso, that the price be paid on the machine being approved? As I am desirous of receiving answers to these inquiries, I send you privately my address. I am, Sir, your's, &c. Cardiff. |