Kitabı oku: «The Mirror of Literature, Amusement, and Instruction. Volume 14, No. 400, November 21, 1829», sayfa 4
Curious Dial
This Dial, which was really no common or vulgar invention, formerly stood in Privy Garden, Whitehall, at a short distance from Gibbons's noble brass statue of James II., which, as a waggish friend of ours said of the horse at Charing Cross, remains in statu-quo to this day. The Dial was invented by one Francis Hall, alias Line, a Jesuit, and Professor of Mathematics at Liege, in Germany. It was set up, as the old books have it, in the year 1669, by order of Charles II.; and in addition to the parts represented in the cut, the inventer intended to place a water-dial at each corner, which he had nearly completed when the original Dial for want of a cover, as he quaintly observes, (which according to his Majestie's Gracious Order should have been set over it in the Winter) was much injured by the snow lying frozen upon it. But there was no chance of obtaining this out of Charles's coffers, and the Dial soon became useless. Its explanation was, however, considered by many mathematical men of the period as too valuable to be lost, and the Professor accordingly printed the description at Liege, in 1673, in which were plates and diagrams of the several parts. The matter was too grave for pleasant, anecdotical Pennant, who, speaking of the Dial, in his London, says "the description surpasses my powers:" he refers the reader to the above work, a "very scarce book" in his time, and we have been at some pains to obtain the reprint, (London, 1685,) appended to Holwell's Clavis Horologiae; or Key to the whole art of Arithmetical Dialling, small 4to. 1712.3
The whole Dial stood on a stone pedestal, and consisted of six4 parts, rising in a pyramidal form, as represented in the Cut.
The base, or first piece, was a table of about 40 inches in diameter, and 8 or 9 inches thick, in the edge of which were 20 glazed dials, with the Jewish, Babylonian, Italian, Astronomical, and usual European methods of counting the hours: they were all vertical or declining Dials, the style or gnomon being a lion's paw, unicorn's horn, or some emblem from the royal arms. On the upper part of the Table were 8 reclining dials, glazed, and showing the hour in different ways—as by the shade of the style falling upon the hour-lines, the hour-lines falling on the style, or without any shade of hour-lines or style, &c. Upon this piece or table stood also 4 globes, cut into planes, with geographical, astronomical, and astrological dials. From the table also, east, west, north, and south, were four iron branches supporting glass bowls, showing the hour by fire, water, air, and earth.
The second piece of the pyramid was also a round table somewhat less than the first, with 4 iron supporters, and dials on the edge, showing the different rising of remarkable stars; the style to each being a little star painted upon the inside of the glass cover. From this piece also branched 4 glass bowls to show the hour by a style without a shadow, a shadow without a style, &c. Upon the upper part of the table were 8 reclining planes, 4 covered with looking-glass, on which the hour-lines, or style of a dial being painted, were reflected upon the bottom inclining planes of the third piece, and there showed the hour. The other 4 had also dials upon them, which were to be seen in a looking-glass placed upon the bottom of the third piece.
The third piece was a large hollow globe, about 24 inches in diameter, and cut into 26 planes, two of which served for top and bottom. The rest were divided into 8 equal reclining planes, 8 equal inclining planes, and 8 equal vertical or upright planes; all of which were hollow. The incliners were not covered with glass, but left open, so as better to receive and show the dials reflected from the second piece. Two of the 8 upright planes towards the north had no bottoms, but were covered only with clear glass, or windows to look into the globe, and thus see the dials as well within as without the same. The other 6 had not only each a cover of clear polished glass, with a dial described on them, like those of the first piece, but had a glass for their bottom; which glass was thinly painted over white, so that the shade of the hour-lines drawn upon the cover, might be seen as well within as without the globe. On these bottom glasses were painted portraits, each holding a sceptre, or truncheon, the end of which pointed to the hour. Two also of the recliners towards the north, had only a glass cover, or window to look into the globe: the other 6 had double glass like the former; their dials being some upon the cover, others upon the bottom; but all so contrived, that the hour could only be known by them, by looking within the globe. From the top of this globe issued 4 iron branches with glass bowls with dials showing the time according to the several ways of counting the hours. These bowls were painted inside so as to keep out the light, except a point left like a star, through which the sun-beams showed the hour; and the place where the hour-lines were drawn, was only painted on the outside thinly with white colour, so that the sun-light passing through the star might be seen, and show the hour.
The fourth piece stood on the globe, had 4 iron supporters, and was a table about 20 inches in diameter, and 6 in thickness! The edge was cut into 12 concave superficies like so many half-cylinders; on each of which was a dial showing the hour by the shade of a fleur-de-lis fixed at the top of each half-cylinder. From the top of this table issued 4 iron branches, with glass bowls, like those of the first, second, and third pieces, though proportionally less. The dials on these bowls showed only the usual hour, and otherwise differed from the third piece; here the hour-lines being left clear for the sunbeams to pass through, that by so passing, they might exhibit the same dial on the opposite side of the bowl, which was thinly painted white, that the said hours might be seen, and show the hour by their passing over a little star painted in the middle.
The fifth piece likewise upon 4 iron supporters, was a globe of about 12 inches diameter, cut into 14 planes, viz. 8 triangles, equal and equilateral; and the other 6 were equal squares. The dials on these planes showed the usual hour by the shade of a fleur-de-lis fastened to the top or bottom of each plane.
The last, or top piece of the pyramid, was a glass bowl of 7 inches diameter, upon a foot of iron. The north side of this piece was thinly painted over white, that the shade of a little golden ball, placed in the middle of the bowl, might be seen to pass over the hour-lines which were drawn upon the white colour, and noted the hour. The bowl was included between two circles of iron gilt, with a cross on the top.
Such is a general description of the parts or divisions of this very curious Dial. To which may be added that the first four pieces had all their sides covered with little plates of black glass, first cemented to the said pieces, except those places whereon the dials were drawn; which being also covered with plates of polished glass, nearly the whole of the outside of the dial appeared to be glass; the angles or corners being elegantly gilt, as were in part the iron work of the pyramid, supporters, branches, styles, &c.
We have abridged and in part rewritten this explanation from upwards of six closely-printed 4to. pages. After the general description, in the original tract, the different sections or parts of the dial, 73 in number, are still further explained, and illustrated by 17 plates, besides a vertical section, of which last our Cut is a copy. Perhaps these details would tire the general reader, and on that account we do not press them: a few of them, however, may be noticed still further.
Of these, the Bowls appear to be the most attractive. One on the first piece, by fire was a little glass bowl filled with clear water. This bowl was about three inches diameter, placed in the middle of another sphere, about six inches diameter, consisting of several iron rings or circles, representing the hour circles in the heavens. The hour was known by applying the hand to these circles when the sun shone, when that circle where you felt the hand burnt by the sunbeams passing through the bowl filled with water, showed the true hour, according to the verse beneath it:
Cratem tange, manusq horam tibi reddet adusta.
The phenomenon is thus explained by the Professor: "the parallel rays of the sun passing through the little bowl, are bent by the density of the water, into a cone or pyramid, whose vertex reaches a little beyond those hour circles, and there burns the hand applied; for so many rays being all united into a point, must needs make an intense heat, which heat is so powerful in the summer-time, that it will fire a piece of wood applied to it."
To many of the Dials were suitable inscriptions as above, and these with the references must have made the construction of the whole a task of immense labour. It would be absurd to expect that Charles II. had much to do with its completion, for he was, in his own estimation, more pleasantly employed than in watching the flight of time by heavenly luminaries. His attractions were on earth, where the splendour of a wicked court and the witchery of bright eyes eclipsed all other pursuits. Still, the licentious king was not forgotten by the inventer of the dial. Among the pictures on some of the glasses were portraits of the king, the two queens, the duke of York, prince Rupert, &c. In the king's picture, the hour was shown by the shade of the hour-lines passing over the top of the sceptre—perhaps the only time the royal trifier ever pointed to so useful an end. Prince Rupert, by his contributions to science, had a better right to be there; but Charles was not even grateful enough for the elevation to protect the precious Dial from rain and snow.
In the list of subscribers for the reprint of the Tract, occurs "Jacob Chandler, basket-maker:" in our times this would be considered a knotty work for any but a professional reader.
