London : Longman, Rees, Orme, Brown, Green, and Longman · leaf 387
r is 23^ in.; and their horizontal section is some-thing of the form shown at b. The height of the masonry overthe crown of each arch is 2 ft. Now, in 13 ft. there are 156 in., which, divided by 6, gives26 in. for the diameter of each pillar: but the diameter is 23^ in.,therefore 2^ in. too small;… … the piers: but the piers are 11 ft. 6 in. As their proportionsapproach so near to each other, it is probable that a mistakemight have been made in the measurement of the diameter, byhaving allowed a trifle too much. The above proportions ex-actly coincide with those required for arches and piers…
Architecture
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