Book IB

THEORY AND PRACTICE OF ENGINEERING.

pendent stone is 17 feet6 inches, and its thick-ness at the top, wherelocked, is 30 inches : thevoussoirs are 3 feet indepth ; the small pointedarches or ribs that formthe groining of the hexa-gonal vault spring fromthe side walls and theornamental knob of thependentive, and are per-fectly independent. Theabutments of the semi-circular arch, which hasa radius of 12 feet, areformed by solid wallscontinued for somelength in the directionof its diameter. Thissacristy is hexagonal;each side internallymeasures 12 feet, and theheight from the pave-ment to the springingof the ribs is 18 feet.

Henry the Seventh’sChapel , Westminster. —

The first appearance ofthe pointed arch wasprobably a little before I®the termination of thetwelfth century; the piU 3054 ' caudebeck sacb.sty.

lars and mouldings which then accompanied it were of Saxon origin : to its acute form was

Fig. 3055.

HER OF HENRY VII. ’S CHAPEL.

afterwards added the slender Purbeck columns and simple groining, producing that unadornedmajesty which reigns throughout the cathedral of Salisbury. This style underwentseveral changes, and was succeeded at the latter end of the thirteenth century by another, in