Imágenes de páginas
PDF
EPUB

burn black and crackle, denote misfortune. On the following morning the stones are searched for in the fire, and if any be missing, they betide ill to those who threw them in.

"The authority assumed by the Bards of excommunication during the purity of the system, was an useful corrective in their discipline: but when the civil government became in a degree coalesced with the order, the sentence pronounced in the circle was clothed in all the terrors that surround an outlaw in modern times Then too, their doctrine of expiation by sacrifice extended to more awful victims, for all the criminals (among whom captives taken in war were often considered the most guilty) were collected together at the great yearly assemblies; and there, in atoning for their offences, presented a spectacle to the whole nation at once impressive aud tremendous.

"In tracing the origin of the Bardic system, we are led back to very remote antiquity. The first who made verse the vehicle of instruction and of record, according to the Triads, was Tydain Tad Awen, or Tydain father of the Muse, between whom and Taaut, Thoth, or Hermes of the Egyptians, there is a striking conformity as well in the names as in their attributes. From this original were derived the privileges and peculiar customs, which were arranged and methodized by the three primeval Bards, Plennydd, Alon and Gwron, and then sanctioned and adopted as a part of the constitution of the nation, and which before only received through courtesy what afterwards was insured by law. The Triads differ as to the period when this took place, whether in the time of Prydain son of Aedd the Great, or of Dyvnwal Moelmud

his son. The exact æra of all these personages is lost in antiquity; but it is curious to observe that the Alon here mentioned, seems to be the same with Olen the Hyperborean, Ailinus or Linus in the Grzcian mythology. It may be pertinent here to notice another Triad, wherein it is said, that Gwyddon Ganhebon was the first who composed verse; that Hu the Mighty was the first who made it the vehicle of record and instruction: and that Tydain Tâd Awen was the first who reduced it to an art, and fixed rules of composition; and hence originated Bards and Bardism, and the regulation of the system in all its privileges, by the three primaval Bards, Plenydd, Alon and Gwron. The Gwyddon Ganhebon above mentioned, seems according to another Triad, to have achieved a work that is to be identified with the pillars of Hermes in Egypt; for this Triad mentions three great exploits, one of them being The stones of Gwyddon Ganhebon, upon which were to be read all the arts and sciences in the world.'

"It does not appear that the Bards had any mythological fables. They had Triads, and other kinds of aphorisms, containing their political, moral, religious, and other maxims and branches of knowledge, which it was necessary that every disciple should learn by heart, before he could gain admission into the order. Of these things as many are still preserved as would take up a long time for a person of common capacity to acquire.

"Whatever superstitions might have originally belonged to the system, must in a great measure, or perhaps totally have been expunged by the introduction of Christianity. In other respects, I believe that the system is still preserved as to the general principles within a

small

small district of Glamorganshire; whilst it has become nearly unknown in every other part of Wales for several ages. This appears more particularly from a celebrated Eisteddvod or congress held at Carmarthen, about the year 1450, against which the synod of the Bards of Glamorgan protested, as being totally subversive of the ancient institutions as preserved by them. This congress at Carmarthen and those subsequently held in North Wales, were scarcely any thing more than the simple meetings of poets and minstrels under a few common and indispensable regulations for the sake of good order; and therefore not worthy of particular notice.

"The chair of Glamorgan being the only one that preserved the ancient Bardic institutes; it is of consequence to bring it more particularly to the notice of the public: for without it, we should have probably nothing left of Bardism or Druidism except in scattered ruins, of which nothing satisfactorily could now be made out.

"This provincial chair or Gorsedd has regularly preserved the ancient discipline, and has occasionally held public meetings to give effect to the functions of the Bards belonging to it. Some of these

meetings were expressly convened at the desire of the Lords Marchers and other powerful families, who were desirous of learning something of this extraordinary system, which was so formed, as to have within itself the means of self-preservation under all the great changes of the nation. And to satisfy the wishes of those noble personages, several of the most intelligent Bards of the times were appointed to collect together and digest every particular relating to the order. Of the congresses convoked By such authoritics, the first was under the patronage of sir Richard Neville; à subsequent one was held under the auspices of William Herbert, earl of Pembroke, at Cardiff castle, in 1570; another in 1580, under the direction of sir Edward Lewis, of the Van; and the last for such special purpose was held at Bewpyr castle in 1681, under the authority of sir Richard Basset.

"The result of these meetings was entered into books, which were revised in the last mentioned congress, and of which manuscript copies are still extant; and the original register of the last meeting is in the possession of Mr. Turberville of Llan Haran in Glamor. ganshire."

[blocks in formation]

ARTS AND SCIENCES.

OBSERVATIONS on REFLECTING TELESCOPES, their METALLIC COM. POSITION, and the MANNER of CASTING them.

[From Mr. LITTLE's Paper in the TRANSACTIONS of the ROYAL IRISH ACADEMY, Vol. X.

[ocr errors]

HERE are but few things produced by the united effort of mechanical artifice and intellectual labour, which have done more honour to the ingenuity and invention of man, than the reflecting telescope; which has many advantages over any of the dioptrical kind, notwithstanding their improvement by achromatic glasses. It will bear a greater aperture, and may be made to magnify more, (as being more distinct,) in proportion to its length, than the others, as they are at present made; and its dimensions and powers are unlimited. What its excellence is, especially the Newtonian construction of it, has been proved by Dr. Herschell, to his own honour, and that of the age, and country, and patronage, which encouraged his labou. s. Accordingly, the persons, eminent for science and mechanical ingenuity, appear to have feit a peculiar and disinterested pleasure, in contributing to its improvement: and the late discovery of a metallic composition for the mirrors of it, which will bear as high a polish as glass, reflect as much light as glass transmits, and endure almost equally yell, with out contracting tarnish, is a farther

4.

encouragement to prosecute its improvement to perfection.

[ocr errors]

Among others, I had formerly, from admiration at its contrivance, bestowed some attention on the mechanism of this instrument: and, as it would have spared me some expence of time and trials, if any other person had previously sug gested to me the hints, which I am to relate; I imagine they will be of use to others, in directing or assisting the course of their labour, in the same pursuit. I had also taken some pains, to understand the me rits of the different constructions of this telescope: but, as this enquiry ended in a conviction, that the Newtonian form of it is the most perfect that can be hoped for; (it being the nature of its great author, to persevere in his researches, till he had arrived at a complete sciution of his doubts, and compre hension of the subject;) so I have only to report what resulted from my experience in the mechanical fabrication of it, as to the method of casting the mirrors, and communicating to them the proper figure.

"Before I had heard of the improvements of the Rev. Mr. Edwards, in the composition of the specula

the precise quantity Mr. Edwards recommends, (though I did so before, in very nearly that proportion,) since I first saw his memoir on that subject. Sir Isaac Newton made trial of a very small portion of it, and found the same effects from it as I experienced: but it is possible, thrat, if it were added in the just proportion discovered by Mr. Edwards, it would be an improvement, and useful ingredient, in the composition.

"I must observe here, that a metal, not liable to contract tarnish from the air, is otherwise suscep

specula for telescopes, I had made many experiments myself with that view; which led me to give full credit to his report of the saperior excellence of that composition composition which he recommends: because I had found, that the qualities of hardness, whiteress, and indopesition to contract tarnish, necessary to a speculum, could not, by any admixture that I could hit upon, be produced, unles, the metal were so highly saturate with tin, as to be excessively brittle; and because I found that this brittleness, how ever inconvenient in some respects, was necessary to reader it susceptible of it accidentally, when there tible of the highest polish: for no metal yet known, except steel, (which, from its disposition to rust, is unit for this purpose,) will take as high a polish as glass will, unless it be more bridle than glass. And indeed this property is common to all substances which we know, that are capable of such polish: they must be very hard, and, as such, brittle; for the polish ing powder employed would stick and bed itself in any soit metal, in stead of cutting and polishing it. "From the result of my trials, I contented myself with the composition mentioned hereafter, as being in every respect sufficient for

the

purpose, and inferior to none in. whiteness, lustre, and exemption from tarnish: for, as to the addition of silver, I found that, when used in a very small quantity, it had an extraordinary property of rendering the metal so soft, that I was deterred from employing it: and unless it shall be found that, without this effect, it makes the metal less porous than otherwise it might be, or less rail and brittle, I am certain that it may, in every other respect, be dispensed with. I had no opportunity to try it, in

happen to be minute holes in its siface, caused by the air, or sand, &c. in casting it. Such cavities will be filled with the dust, or rusty solution of the brass, in grinding; which will, in time, become a sort of vitiol, and act on the contiguous parts of the speculum, producing a canker in it, which will spread, in form of a cloud of tarnish, around each cavity. In such a case, to prevent this, I would advise, to lay the mirror, as soon as polished, in warm water, and, after drying, while it remains heated, to rub it over with spirit-varnish; from which it may be cleansed, by a piece of fre hen dieped in spirit of wine. The varnish will remain in the cavities; and, by defending the inpurities in them from the action of the air, will probably preserve them from becoming corrosive to the metal.

"From numerous experiments, of the qualities of different compositions, made by several persons, it appears, that no combinations, of any other metals or semi-metais, are fit for specula, except those of copper, brass, tin, silver, and arsenic. I tried no semi-metal, except the latter, which whitens copper, and Q &

unites

unites intimately with it; because it is stated, in the treatise of the Art of Assaying, by the observant and accurate Cramer, that all the semi-metals rise in flowers, during the fusion which would certainly make the metal porous. On this account, I would have rejected the brass, because of the zinc contained in it; but that it seemed to render the composition whiter, and less apt to tarnish, than it would be without it. It will have little tendency to rise in flowers, if the speculum-metal be fused, with the lowest heat requisite, and if the brass be of the best kind; because, in this, the zinc is more perfectly united with the copper, and both are purer. I used, for this purpose, the brass of pin-wire: and, because the quantity of it was only the one eighth part of the copper employed, which, I imagined, would receive too fierce a heat, if put alone into the melted copper; I first added to the brass, in fusion, about an equal quantity of the tin, and put the mass cold into the melted copper; supplying after ward the remainder of the tin, and then the arsenic; the whole being generally in the following proportion: viz. 32 parts best bar copper, previously fluxed with the black fiux, of two parts tartar, and one of nitre, 4 parts brass, 164 parts tin, and 1 arsenic. I suppose, with others, that, if the metal be granulated, by pouring it, when first melted, into water, and then fused a second time, it will be less porous than at first.

"In this process, whatever metals are used, and in what proportions soever, the chief object is, to hit on the exact point of saturation of the copper, &c. by the tin. For, if the latter be added in too great quantity, the metal will be dull

coloured and soft; if too little, it will not attain the most perfect whiteness, and will certainly tarnish. It is too late to discover the imperfections of the metal, after the mirrors are cast and polished; and no tokens given of them (that I know) are sufficiently free from ambiguity. But I observed the following, which proved, in my trials, at first view, indubitable marks of the degree of saturation; and I think it fit to describe them particularly, as they have not, to my knowledge, been noticed by others.

"When the metal was melted, and before I poured it into the flask, I always took about the quantity of an ounce of it, with a small ladle, out of the crucible, and poured it on a cold flag; and observed the following appearances.

"First. If the metal assumed, in cooling, a lively blue, or purple colour, commonly intermixed with clouds, or shades of green or yel low; and if, when broken, the face of the fracture exhibited a silvery whiteness, as bright and glistening as quicksilver, without any appearance of grain, or inequality of texture; then the degree of saturation of the metal, with the tin, was complete and perfect.

"Secondly. If the surface of the metal became of a dun or mouse colour, and especially if of a brown or red; and, when broken, the fracture exhibited a more yellow, or tawny hue, than that of quicksilver; then the quantity of tin in the composition was deficient, and it was necessary to add more.

"Thirdly. If the colour was an uniform dull blue, like lead, and, where broken, discovered a dull

colcur,

« AnteriorContinuar »