. Bulletin - United States National Museum. Science. Albion would apjpcar to correspond very closcl\- in- deed to the dial-work which forms the greater part of the de Dondi clock, and for this reason we suggest now thai ihv two clocks were very closely related in other ways too. This, circumstantial though it be, is evidence for thinking that the weight drive and some form of escapement were known to Richard of Wallingford, ca. 1320. It would narrow the gap be- tween the clock and the protoclocks to less than half a century, perhaps a single generation, in the interval ca. 1285-1320. In this c
. Bulletin - United States National Museum. Science. Albion would apjpcar to correspond very closcl\- in- deed to the dial-work which forms the greater part of the de Dondi clock, and for this reason we suggest now thai ihv two clocks were very closely related in other ways too. This, circumstantial though it be, is evidence for thinking that the weight drive and some form of escapement were known to Richard of Wallingford, ca. 1320. It would narrow the gap be- tween the clock and the protoclocks to less than half a century, perhaps a single generation, in the interval ca. 1285-1320. In this connection it may be of interest that Richard of Wallingford knew only the Toledo tables corpus, that of the Alfonsine school did not arrive in England until after his death. There are, of course, tnany literary references to the waterclocks in medieval literature. In fact most of these are from quotations which have often been produced erroneously in the history of the mechanical It seems probable that some of these water clocks could have been sim|5le drip clepsydras, with jx-r- haps a striking arrangement added. A most fortu- nate discovery by Drover has now brought to light a manuscript illumination that shows that these water clocks, at least by ca. 1285, had become more complex and were rather similar in appearance to the Alfon- sine mercury ; The illustration (fig. 19) is from a moralized Bible written in northern France, and accompanies the passage where King Hczekiah is given a sign by the Lord, the sun being moved back ten steps of the clock. The picture clearly shows the central water wheel and below it a dog's head spout gushing water into a bucket supported by chains, with a (weight ?) cord running behind. Above the wheel is a carillon of bells, and to one side a rosette which might be a fly or a model sun. The wheel appears to have 15 compartments, each with a cen-. Figure i8.—Ge.^r Tr.\in of in figure 17. {Pholo courtesy of Science Museum, Lon
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