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 drum." 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 

 Poi.NTER in figure 17. {Pholo 

 courtesy of Science Museum, London.) 



clock, thereby providing many misleading starts for 

 that history, as noted previously in the discussion of 

 the horologium. There arc however enough men- 

 tions to make it certain that water clocks of some sort 

 were in use, especially for ecclesiastic purposes, from 

 the end of the 12th century onwards. Thus, Jocelin 

 of Brakelond tells of a fire in the Abbey Church of 

 Bury St. Edmunds in the year 1198.'' The relics 

 would have been destroyed during the night, but just 

 at the crucial moment the clock bell sounded for 

 matins and the master of the vestry sounded the 

 alarm. On this "the young men amongst us ran to 

 get w-ater, some to the well and others to the clock"' — 

 probably the sole occasion on which a clock served 

 as a fire hydrant. 



tral hole (perhaps similar to that in the Alfonsine 

 clock) and it is supported on a square axle by a 

 bracket, the axle being wedged in the traditional 

 fashion. The projections at the edge of the wheel 

 might be gear teeth, but more likely they are used only 

 for tripping the striking mechanism. If it were not for 

 the running water spout it would be very close to the 

 Alfonsine model; but with this evidence it seems impos- 

 sible to arrive at a clear mechanical interpretation. 



" The Chronicle oj Jocelin oj Brakelond . . ., H. E. Butler (<-cl.), 

 London, 1949, p. 106. 



'* C. B. Drover, "A medieval monastic water-clock," .An- 

 tiquarian Horologt; 1954, vol. 1, no. 5, pp. 54-58, 63. Because 

 this water clock uses wheels and strikes bells one must reject 

 the evidence of literary reference, such as by Dante, from 

 which the mention of wheels and bells have been taken as 

 positive proof of the exi.stencc of mechanical clocks with 

 mechanical escapements. The to-and-fro motion of the 

 mechanical clock escapement is quite an impressive feature, 

 but there seems to be no litrr.irv reference id it before the 

 time of dc Dondi. 



PAPER 6: CLOCKWORK, PERPETUAL MOTION DEVICES, AND THE COMP.\SS 



105 



