He starts out like this:
"Keystones are not needed. So we don't need a page about keystones. Ah well, let's just fill up this page with miscellaneous observations about beams and arches. Actually, you will probably have already realised from the existence of three-pin arches that the keystone is inessential"
Yet also includes this:
"Since this page is rather negative about keystones, we could also mention an article in Arab Construction World Nov 2005 / Vol XXII - Issue 7, in which Hakan Sandbirg points out that the value of the keystone is that it reminds us that "until the structure is complete, we have to keep thinking" - an important point"
And so I just couldn't stop reading and finished the whole chapter on, well, keystones - from this great site.
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In keeping with the general video friendly theme of the blog I've added some Keystone Cops documentary footage below ( Although the article was awesome I just couldn't find any interesting video footage about actual keystones).
