_Antiquarian Horology_, 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 existence 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 literary reference to it before the time of de
Dondi.

[35] _Annales de la Societe Royale d'Archeologie de Bruxelles_,
1896, vol. 1/8, pp. 203-215, 404-451. The translation here is
cited from Drover, _op. cit._, (footnote 34), p. 56.

[36] L. Thorndike, _The sphere of Sacrobosco and its
commentators_, Chicago, 1949, pp. 180, 230.

[37] The album was published with facsimiles by J. B. A.
Lassus, 1858. An English edition with facsimiles of 33 of the
41 folios was published by Rev. Robert Willis, Oxford, 1859. An
extensive summary of this section is given, with illustrations,
by J. Drummond Robertson, _The evolution of clockwork_, London,
1931, pp. 11-15.

[38] M. Jules Quicherat, _Revue Archeologique_, 1849, vol. 6.

[39] M. C. Fremont. _Origine de l'horloge a poids_, Paris,
1915.

[40] For this, I have used and quoted from the very beautiful
edition in English, prepared by Silvanus P. Thompson, London,
Chiswick Press, 1902.

[41] See E. G. R. Taylor, "The South-pointing needle," _Imago
Mundi_, Leiden, 1951, vol. 8, pp. 1-7 (especially pp. 1, 2).

[42] I have wondered whether the medieval interest in perpetual
motion could be connected with the use of the "Wheel of
Fortune" in churches as a substitute for bell-ringing on Good
Friday. Unfortunately I can find no evidence for or against the
conjecture.

[43] W. E. May, "Alexander Neckham and the pivoted compass
needle," _Journal of the Institute of Navigation_, 1955, vol.
8, no. 3, pp. 283-284.

[44] W. E. May, "Hugues de Berze and the mariner's compass,"
_The Mariner's Mirror_, 1953, vol. 39, no. 2, pp. 103-106.

[45] H. Balmer, _Beitraege zur Geschichte der Erkenntnis des
Erdmagnetismus_, Aarau, 1956, p. 52.

[46] The collection is the _Gami 'al Hikajat_; the relevant
passage being given in German translation in Balmer. _op. cit._
(footnote 45), p. 54.

[47] Balmer, op. _cit._ (footnote 45), p. 53.

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