and even the distaiicf Ironi each other he demonstrated to 

 his pupils most elTcciually. Just how he accomplished this 

 it is unsuitable to enter into here because of its extent lest 

 we should appear to be wandering from our main theme. 



Thus, although there is a hint of mechanical com- 

 plexity, there is really no jtistification for such an 

 assumption; the description might well imply only 

 a zodiac band on which the orbits of the planets were 

 painted. On the other hand it is not inconcei\ablc 

 that Gerbcrt could have learned something of Islamic 

 and other extra-European traditions during his 

 period of study with the Bishop of Barcelona — a 

 traveling scholarship that seems to have had many 

 repercussions on the whole field of Evnopean 

 scholarship. 



Once the floodgates of Arabic learning were 

 opened, a stream of mechanized astronomical 

 models poured into Europe. Astrolabes and equaloria 

 rapidly became very popular, mainly through the 

 reason for which they had been first devised, the 

 avoidance of tedious written computation. Many 

 medieval astrolabes have survived, and at least 

 three medieval equatoria are known. Chaucer is 

 well known for his treatise on the astrolabe; a manu- 

 script in Cambridge, containing a companion treatise 

 on the equatorium, has been tentatively suggested 

 by the present author as also being the work of 

 Chaucer and the only piece written in his own hand. 



The geared astrolabe of al-Biruni is another type of 

 protoclock to have been transmitted. A specimen in 

 the Science Museum, London,"* though unfortunately 

 now incomplete, has a very sophistocated arrange- 

 ment of gears for moving pointers to indicate the 

 correct relative positions and movements of the sun 

 and moon (see figs. 17 and 18). Like the earlier 

 Muslim example it contains wheels with odd numbers 

 of gear teeth (14, 27, 39); however, the teeth arc no 

 longer equilateral in shape, but approximate a more 

 modern slightly rounded form. This example is 

 French and appears to date from ca. 1300. Another 

 Gothic astrolalje with a similar gear ring on the retc, 

 said to date from ca. 1400 (it could well be much 

 earlier) is now in the Billmeier collection (London).-' 



Turning from the mechanized astrolabe to the 

 mechanized equatorium, we find the work of Richard 

 of VValiingford (1292?-1336) of the greatest interest 



as providing an immediate precursor to that of do 

 Dondi. He was the son of an ingenious blacksmith, 

 making his way to Mcrton College, Oxford, then the 

 most active and original school of astronomy in 

 Europe, and winning later distinction as .Abbot of .St. 

 Albans. A text by him, dated 1326-27, described in 

 detail the construction of a great equatorium, more 

 exact and much more elaborate than any that had 

 gone before.'" Nevertheless it is evidently a normal 

 manually operated device like all the others. In 

 addition to this instrtiment, Richard is said to have 

 constructed ca. 1320, a fine planetary clock for his 

 .'\bbcy.'' Bale, who seems to have seen it, regarded 

 it as without rival in Europe, and the greatest curiosity 

 of his time. LInfortunately, the issue was confused by 

 Leland, who identified it as the Albion {i.e., all-by 

 one), the naine Richard gives to hLs manual equa- 

 torium. This clock was indeed so complex that 

 Edward III censured the Abbot for spending so much 

 money on it, but Richard replied that after his death 

 nobody would be able to make such a thing again. 

 He is said to have left a text describing the construc- 

 tion of this clock, but the absence of such a work has 

 led iTiany modern writers to support Leland's identi- 

 fication and suppose that the device was not a mechani- 

 cal clock. 



A corrective for this view is to be had from a St. 

 Albans manuscript (now at Gonville and Caius Col- 

 lege, Cambridge) that described the methods for 

 setting out toothed wheels for an astronomical horo- 

 logium designed to show tlie motions of the planets. 

 Although the manuscript copy is to be dated ca. 1340, 

 it clearly indicates that a geared planetary device 

 was known in St. Albans at an early date, and it is 

 reasonable to suppose that this was in fact the ma- 

 chine made by Richard of \VaIlingford. L'nfortu- 

 natcly the text docs not appear to give any relevant 

 information about tlie presence of an escapement or 

 any other regulatory device, nor docs it mention 

 the source of power.'" Now a geared version of the 



" Item 198 in Gunthcr, op. cil. (footnote 21). I am grateful to 

 the authorities of that museum for permission to reprocluee 

 photographs of this instrument. 



» Sotheby and Co., London, sale of March 14, 1957, lot 154. 

 The outer rim of the rctc has 120 teeth. 



'" The Latin text of the treatise on the Albion, has been 

 transcribed by Rev. H. Salter and published in R. T. Gunthcj, 

 Early science in Oxford, Oxford, 1923, vol. 2. pp. 349-370. .An 

 analysis of its design is given in Price, op. cit. (footnote 23), pp. 

 127-130. 



" Such evidence as there is for the existence and form of the 

 clocl- is collected by Gunthcr, np cil. (footnote 30), p. 49. 



3- I have discussed this new manuscript source in "Two 

 medieval texts on astronomical clocks," .InliqiinrKin Horology, 

 1956, vol. 1, no. 10, p. 156. The manuscript in question is 

 ms. 230/116, Gonville and Caius College, Cambridge, folios 

 ll>-14'' = pp. 31-36. 



PAPER 6: CLOCKWORK, PERPETUAL MOTION DEVICES, AND THE COMPASS 



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