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the more simple of three days or lower divisions, the head is occupied by three circles, each of which contains a trefoil constructed upon the crossing of either three or four equi. lateral triangles.
A very extraordinary design, composed of intersecting circles, is to be seen at the east end of the chancel of the church at Sutton, at Hone, in Kent; although much dilapidated, it still preserves many of its original Aowing lines, all struck from the same radius, through points previously determined by crossing the primitive circle by four equilateral triangles.
At half the height of the head of the window a horizontal line may be supposed to be drawn from one side to the other, on which are three circles: the two outer touching, are crossed by the third, struck from the point of their junction; with the same radius several spherical triangles are struck from the points of intersections, producing the lines, which unite and divide the window head into several compartments, differing in pattern and dimension. After the circles were struck, the lines that did not play into each other were left out, and those only retained which flowed on gracefully; by these nice considerations and just application of principles, the masons were cer. tain of producing a perfect effect, without rigidly adhering to any particular form.
Windows of four Days or Divisions. — Among the heads of a more simple character are those which contain one large circle, subdivided by three equilateral triangles, each
HONE CHURCH, KENT.
inclosing a trefoil. Others contain, in adulition to the one great equilateral triangle, two smaller, constructed upon the points of its base, and dropping into the space comprised between the heads of the divisions below.
Windows of Six Divisions are far more complicated, and, though exhibiting greater skill in geometry, are set out precisely upon the same principle. The two equilateral triangles inclosed within the great circle mark out the prominent features of the design, and their terminations are the centres of as many spherical triangles, which, by their crossing, constitute the elaborate filling in.
In some examples, above the two main lower divisions is a circle divided by several others, the twelve which are indicated in the figure serving to proportion the tracery of this compartment.
At the latter end of the fourteenth century, these designs were so multiplied that almost every cathedral and church had its peculiar windows: in Amiens cathedral, the chapels constructed at this same time receive their light from windows, the heads of which are filled in with tracery exceedingly varied, but the general principles of setting out the work are preserved; the circle and the equilateral triangle were subdivided
Fig. 1285. almost to infinity, and at no period of the arts do the inventive faculties appear so fertile as in that we are now considering The great west window of York Cathedral is the finest example of the improvement made in this mode of decoration; the geometric forms are there so concealed by the blending of the several curves, as to produce continued flowing lines, which is partly shown in fig. 1282. : they are, however, all set out in the same manner, and the centres upon which they are struck are established by the crossing of equilateral triangles.
During the episcopacy of John Grandisson, from the year 1927 to 1369, Exeter Cathedral was undergoing an entire change Fig. 1286. in its architecture, To this bishop we are indebted for the great west window, of nine days, and several smaller of four and five, in which are introduced tracery showing a great variety of design: some are composed of equilateral triangles, each containing å trefoil, some of circles with six turns, others have four and three; but the heads of all, varied as they are, belong to the same school as fig. 1285.
The great east window at Bristol Cathedral is another fine example of nine days,
executed about the middle of the 14th century; the centre of the head of the window, or rather the nucleus to the tracery, is an octagon, six sides of which are retained, the other two being suppressed, to allow of a better combination with the three centre divisions of the lower part.
The equilateral triangle also defined the form and magnitude of the several mullions, as shown by fig. 1287., constructed upon measurement of the windows of the clerestory of the nave at Winchester : a line drawn from the apex of one mullion to the other is the base of the triangle, and the space inclosed by the two is divided into ten other equilateral triangles, two of which agree in dimensions and form with each mullion. Of the twelve equilateral triangles embracing two half mullions, ten are given to the day or space to admit the light, and two, or onesixth of the whole, is comprised by the mullion; such appears to have been the manner of proportioning the
Fig. 1287. See also fg. 1303. WINCHESTER, parts of windows in the middle ages.
Rose Windows in the West Transept of the Church of St. Ouen at Rouen is 29 feet 6 inches in diameter, and composed of seven equal circles, one of which occupies the centre : each of those, which surround it, are again subdivided by others; two only of the outer six are preserved in the figure, and form the quatrefoils, whilst the intersections of the others serve as centres to the rest of the design.
ST. QUEN AT ROUEN,
Fig. 1288. Rose Window of the South Transept of the Cathedral at Rouen is 23 feet in diameter, measured to the centre of the large bead, which comprises the figure. A portion only of
this beautiful example is given, for the purpose of exhibiting the principle upon which it is set out: it will be evident that the nucleus of the design is composed of two equilateral triangles, and the sides of each continued, constitute the
The internal hexagon has its parallel sides prolonged, to mark the position of the four divisions that have their pointed heads attached to the small circle, which forms the eye of the pattern; and the length of these prolonged lines is limited to the extent of the sides of an equilateral triangle, which is again divided regularly, the triangular spaces between being filled in with trefoils. The small mullions are in width 24 inches, the next size 3 inches, and those which mark out the figure and have a bead for their termination are 44 inches : another bead and bold projecting label, or rim, circumscribe the whole rose window, the hollow around which is enriched with a curved leaf. On each side of the internal hexagon an equilateral triangle is constructed, around which a circle is struck, uniting elegantly with the next, and forming the six turns which characterise the filling in of
circles at this period; these were the principal decorations after the Lancet style was abandoned, and were continued until succeeded by more flowing and varied designs.
Rose Window of the South Transept at Beauvais, 34 fuet 4 inches in diameter, is composed of six large circles and their intersections.
To set out this window the great circle expressed by the outer bead is divided into twelve parts, each being equal to half the radius; twelve equilateral triangles are then inscribed, the points of which touch each of the divisions, and where they cross nearest to the outer circle, the twelve pointed arches that surround the figure are struck; the other points of intersection of the triangles are centres, from which the other curves are drawn. It must at once. be evident, that in a circle so divided, or by any other equal number of equilateral triangles, the portions contained between the smaller angles must be equal to each other; the six circles around the centre have their curves blended into the outer, and if it be required to fix centres for each of these flowing lines, they can only be obtained by covering the entire rose window with lines in the manner already described. The radius being equal to the side of a hexagon, and that figure being composed of two equilateral triangles, was probably the chief reason of its first preference over all others; it certainly affords the most extraordinary
Fig. 1291. BEAUVAIS CATHEDRAL: SOUTH TRANSEPT. powers of combination, and there is carcely a moulding or form in the architecture of this period but is set out from it. The mullions that bound the divisions are all portions of this figure, as are the mouldings, which sweep round the arches of the buildings themselves. Nothing can surpass the brilliant effect of these marigold windows when glazed with rich colours, and exposed to either a rising or setting sun; in the example now described, this effect is still further heightened by making nearly the whole end of the southern transept a continuation of the same design, the glass descending almost to the tops of the doors which afford access to the cathedral. The construction of such works must excite our highest admiration, for it appears scarcely possible to excel the perfect manner in which the parts are put together and worked off, the execution being in every particular worthy the design.