1632

THEORY AND PRACTICE OF ENGINEERING.

Book II.

small columns on the fall towards the nave, or the single column on that towards the sideaisles, the first of which projects 6^ inches, and the latter 4 inches.

The mouldings around the windows and their mullions are shown at the side of thepier in their proper position.

Division of the Nave of St. George's Chapel — The mouldings set around the plan ofthe pier are continued up to the vaulting of the roof, without any other interruptionexcept where they are mitred round the arches.

Bath Abbey Church is 89 feet 5 inches in width from cut to cut measured across the nave,and the clear width of the nave is 29 feet 10 inches, or one-third of the whole, and each ofthe side aisles is a trifle more than the half of the width of the nave, being 15 feet 8 inches ;the walls and piers added together are not quite equal to a third, as they amount only to 14feet 2 inches on each side, or together to 28 feet 4 inches, the difference being given toincrease the side aisles.

The section of this beautiful building presentsto us all the improvements made in vaulting, and theright proportions as well as directions to be givento the flying buttresses: in the first application ofthose supports, as at Salisbury, they are evidentlymisapplied, but in the example before us we findthat the constructors had arrived at a knowledgeof the principles of the catenarian curve, whichis traceable through the solid masses of the section :it was by slow degrees that the freemasons arrivedat a knowledge of the peculiar properties of thisfigure; had it been known at the first commence-ment of the introduction of flying buttresses, weshould have had a better application of them; inseveral instances we find them adopted where noadvantage, or very little, could be derived fromthem.

Division in Bath Abbey Church differs from allother examples of this period, by the height givento the clerestory and the omission of the triforium :the judicious and excellent arrangement of theflying buttresses permits of the greater displayof glass, which in the sixteenth century had arrivedat its most gorgeous state, rich in every colour, andbeautiful from the drawing of the patterns, andfigures with which it was covered.

Bishop King commenced this building about theyear 1500, on an entirely new site, near the oldchurch: from the centre of one pier to that of theother is 20 feet 1 inch; the thickness of the outerbuttresses 3 feet, and their projection 4 feet; onesevery of building contains 1 650 feet, and the areaof the points of support is 275 feet, or one-sixth.

The pillars are square, though set diagonally, theirwidth from north to south and from east to westbeing 5 feet, and the opening of the arches between them 15 feet 1 inch ; half their planand base is shown at fig. 3052.: the height from the pavement to the top of the capitals,where the sculptured angel is placed, is 56 feet 3 inches, and to the top of the vaulting73 feet 6 inches, within 7 feet as much as the clear width between the outer walls.

Fig. 3053. shows the plan of the stone vaulting, which is perfectly geometrical in itssetting out; the cloisters at Gloucester, the aisle at the east end of Peterborough cathedral ,and St. George’s Chapel, Windsor, have vaults of a similar kind.

The thickness of the stone which comprises the vaults of fan tracery varies according toits position, but in no instance is it considerable, or more than absolutely necessary to resistcrushing. The spire of Salisbury, 180 feet in height, of an octangular form, measures fromeast to west internally 33 feet 2 inches, and from north to south 6 inches more; thethickness of the spire at bottom is only 2 feet, or the area of its base is half that of thevoid, the void containing two parts, and the solid around it one; this spire diminishes inthickness for the first 20 feet, after which it is 9 inches in thickness throughout; at about30 feet from the summit is a hole, by which an exit from the interior may be made, andby means of the crockets and irons on the outside the top of the spire may be attained: in1816 the writer examined the position of the vane, and the manner in which the cappingstone was placed, and descended astonished at the perfection of the masonry, and thethinness of the stone with which it was constructed.

Fig. 3049. BATH ABBEY CHURCH.