of the line of their profeffion, they have been properly inferted. As a fpecimen of this kind, we fhall transcribe the Life of John Blagrave.

of

'John Blagrave, born Died, 1611. An excellent mathematician. He was the second son of John Blagrave, of Bulmarsh-Court, in the county of Berkshire. The former part his education he received at Reading, from whence he removed to St. John's college, Oxford. When he quitted the university, where he did not long refide, he retired to Southcote-Lodge, and devoted his time to ftudy, his genius chiefly leading him to the fcience of mathematics. He alfo reduced his ftudies to practice, and gave to the public the fruit of his labours. He was a man of a benevolent difpofition; and his judicious charities are still remembered at Reading with gratitude. One efpecially is too fingular to be omitted in this place. Annually, on Good Friday, he appointed the church-wardens of the feve ral parishes in that town, to choose three maidens of fair cha racter, each of which had lived three years in her place, and to bring them to the town hall, where, before the mayor and aldermen, they caft dice; and the who is fo fortunate as to throw the highest number, is prefented with a purfe containing ten pounds, and attended by the other two maidens who loft the caft. The year following, the maidens, who loft the cast the year before, come again, with a third added to them, and throw again. But if any one is fo unfortunate as to lose three throws, the cannot caft a fourth time, but is excluded from the benefit of the charity. Mr. Athmole, who gives a full account of this custom, adds: "it is lucky money; for I never heard, but that the maid that had the ten pounds fuddenly got a good hufband." Mr. Blagrave died at his houfe near Reading, Auguft 9, 1611, and was interred, near his mother, in the church of St. Lawrence, in that town. His principal works are the following a Treatise on the making and using the Familiar Staff. The Aftrolabium Uranicum generale. The Art of Di alling, and the Mathematical Jewel. This laft is his greatest and most efteemed performance. It was printed in 1585, at London, with this note in the frontispiece: By John Blagrave of Reading, gentleman, and well-willer to the mathematics, who hath cut all the prints or pictures of the whole with his own hands." They are wooden cuts, and neatly executed. Where he has not put his name at length, it is thus abreviated," J. Blag. fculp."

As a fpecimen of his characters of the ftyle of engravers, we shall select the following account of that of Cornelius Bloemart,

The manner of engraving, adopted by this excellent artist, appears to me to be not only quite original, but the fource from

which we may trace that ftyle, in which the greatest and best French mafters excelled: thofe I mean, who worked with the graver only. He covered the lights upon his diftances, and the other parts of his plates, which required tinting, with great care. The lights, whether on the diftant hills, trees, buildings, or figures, in the engravings prior to his time, had been left quite clear, and by fo many white fpots fcattered, in various parts of the fame defign, the harmony was deftroyed, the fubject confufed, and the principal figures prevented from relieving with any ftriking effect. By this judicious improvement, Bloemart gave to his prints a more clear and finished appearance, than all the laboured neatness even of Jerom Wierix had been able to produce.

He drew correaly; but from his ftyle of engraving, which is executed entirely with the graver, the extremities of his figures are heavy; and his heads are not always equally beautiful or expreffive. With refpect to the mechanical part of the works, few indeed have excelled him, either in clearness or freedom of execution. His great fault, however, is want of variety. The naked parts of his figures, the draperies, and. the back-ground, are equally neat, and engraved precifely in the fame manner. Hence the effect is flat, and the flesh, for want of fufficient diftinction, appears cold and filvery. His works are justly held in high estimation.'

In other parts, he inferts ufeful cautions to collectors, which may be attended to with advantage. Speaking of the works of Scheltius a Bolfwert, he obferves,

It is very neceffary to caution the collectors of this mafter's works (thofe efpecially who are not very converfant with them), that many of them have been copied in a very careful manner, so as easily to deceive the unskilful. Some of thefe copies, as the Marriage of the Virgin, from Rubens, &c. are by Lawers. But those which are most likely to mislead are by Ragot, a French engraver, employed by Mariette the print-feller, who frequently meeting with the reverses or counter-proofs, from the prints of Bollwert, gave them to the engraver; and he imitated them with the utmoft precifion. By this means the impreffions from the plate copied come upon the paper the fame way with the original. It is true, his name is ufually affixed at the bottom; but it is often cut off, and then the copy is not cafily diftinguished from the original. Among other prints thus imitated by Ragot from Bolfwert, is Chrift crucified between the two thieves; where the foldier is represented piercing his fide, from Rubens.'

At the end of the volume is a very full collection of engravers marks and monograms, with an Effay on the Art of Engraving, and fome obfervations on the fubject, by another

G4

hand.

hand. We entirely agree in this ingenious author's opinion, that of all the imitative arts, engraving is moft applicable to general use. Prints, from the facility with which they are multiplied, have a great advantage over paintings. Many of the best paintings of the early mafters have been executed on walls, or depofited in damp unfrequented buildings; while a print, with common care, paffes unhurt from one collection to another. In England, where capital performances of the ancient masters are very scarce, we are much indebted to prints for giving us proper ideas respecting their merits. As far as defign, compofition, and drawing, are concerned, a print is equally estimable with a picture; and if the painter was a bad colourist, as was the cafe with Peter Tefta, the print gives him a reputation, which, on account of that defect, he never would have acquired from the picture. What printing has been with respect to general fcience, engraving has been to the arts; and the works of the old Italian masters will be indebted to engraving for that perpetuity which the invention of printing has fecured to the Jerufalem of Taffo, and the tragedies of Shakspeare and Corneille.'

Mr. Strutt very accurately examines the different evidences in favour of Italy and Germany, in respect to the invention of engraving plates for impreffions, and concludes that there is the greatest reafon to believe, that the art was practifed in Germany before it reached Italy. It did not appear in Italy before the year 1460; while it may, with the greatest justice, be placed ten years earlier among the Germans. The author is of opinion, that the art was practifed in its infancy, in our own country, of which he produces a fpecimen, together with feveral other plates, either originals, or copies from the oldeft mafters.

This volume finishes with the letter G, and abounds with information, fuperior to any work we have seen on the fame fubject. We hope that the author will complete his defign, fo foon as the great attention and care, neceffary for the purpofe, will permit. In the profecution of it, we would advise him to write aqua tinta, inftead of aqua tinto, which is a vulgarifm much beneath a writer of his rank.

Philofophical Tranfactions of the Royal Society of London. Vol. LXXV. For the Year 1785. Part I. (Concluded, from p. 59.) Rticle XI. Obfervations and Experiments on the Light of Bodies in a State of Combuftion. By the Rev. Mr. Morgan, The experiments and conclufions of Mr. Morgan

are

are very ingenious. As it feems now to be generally acknowledged, that light is a body, confifting of different parts, capable of becoming a component part of other bodies, and of being feparated by a fuperior attraction, Mr. Morgan examines the phænomena of combustion, to ascertain the manner of its feparation. It appears, from this enquiry, that the moft refrangible rays are decompofed with the leaft heat, and the leaft refrangible only with a greater; but befides the mere power of heat, there are other modes of retarding or accelerating the combuftion of bodies.

1. A candle burns moft rapidly and brilliantly in dephlogifticated air.

2. The blue column of a fulphureous flame in pure air is changed into a dazzling white.

6 3. The flame of inflammable air, when mixed with nitrous air, is green. It is white ftrongly tinged with the indigo and violet when mixed with common air; but when mixed with dephlogisticated air, or furrounded by it, the brilliancy of its flame is moft fingularly beautiful.

If a

If the preceding facts prove that light, as an heterogeneous body, is gradually decompofed during combuftion; if they prove, likewife, that the indigo rays escape with the leaft heat, and the red with the greateft; I think we may rationally account for feveral fingularities in the colours of different flames. piece of paper, impregnated with a folution of copper in the nitrous acid, be fet on fire, the bottom and fides of the flame are always tinged with green. Now this flame is evidently in that weak state of decompofition, in which the most refrangible rays escape in the greatest abundance; but of thefe rays the green efcaped moft plentifully through the unignited vapour, and that portion of the atmosphere which separates the eye from the flame. The peculiarity which I have now endeavoured to account for may be obferved in the greatest perfection in brass founderies. The heat in this inftance, though very strong, is fcarcely adequate to the decompofition of the metallic vapour which efcapes from the melted brafs. A very fingular flame, therefore, appears to the eye; for while its edges are green, its body is fuch as to give the objects around a very pallid or ghaftly appearance, which is the confequence of its wanting that portion of red rays which is neceffary to make a perfect white.'

Many other fingularities, in the appearance of flame, are examined and explained on the fame foundation, with equal ingenuity.

The appearances of electric light next claim Mr. Morgan's attention. Every fluid or folid body may be made luminous by the paffage of electric light; but the difficulty of making

any

any body luminous is greater, the more powerful that body is as a conductor, or the more its denfity is increased. Again, the brilliancy and splendour of the electric fluid, in its passage through any body, are increased by leffening the dimenfions of that body; and the influence of different media, on electric light, is analogous to their influence on folar light. Thefe feveral pofitions are elucidated by decifive experiments. The conclufions from them are equally ingenious; but they would not be easily intelligible without the experiments, fo that we must refer to the volume.

In the obfervations on phofphoric light, Mr. Morgan objects to Mr. Wilfon's opinion, that it proceeds from a flow combuftion; and, with more reafon attributes it to the light of the fun not being immediately reflected, but to its being retained with some force, though not actually absorbed. In fact, the phosphoric light is nearly in the same state with heat, which, when added to a body, and not combined with it as a component part, gradually escapes. As fome bodies receive heat by exposure to it, into their compofition, without allowing it to escape, fo fome metallic calces are changed in confequence of expofure to light. Again, phofphoric light is fometimes feparated by heat, but not attended with any additional heat; and, in this cafe, we approach more nearly to Mr. Wilfon's opinion of its being a mode of combustion. But we must not indulge ourselves too much in these reflections.

Art. XII. On the Conftruction of the Heavens. By Wil liam Herfchel, Efq. F. R. S.-The magnitude of the objects, the vaft diftance, and amazing extent of the fields of view, mentioned in this paper, fill the mind with ideas fo immenfe, that it is loft in the contemplation; and, when we endeavour to pursue them in imagination, we often lofe fight of the whole. We have frequently experienced this obfcurity in reviewing Mr. Herfchel's researches: we now feel it with additional force; fo that we fear our account of this paper will appear imperfect and obfcure. We cannot enter on it at any length; for then our article muft equal the original.

A reader of Mr. Herfchel's works muft poffefs a lively imagination, and a clear ready comprehenfion: he must forget his former ideas of fixed ftars being scattered in parallel planes; and must learn to conceive as many different inclinations of them, as there are varieties of nebulæ or systems.

At page eighteenth of the last volume, we gave. some account of the author's first paper on this fubject. He now pursues his former reasoning. The groups, he fuppofes, may be formed by the laws of attraction: if we originally fuppofe the ftars

fcat.