e
line indicates that it was not really a full-size steeple but rather a
small towerlike structure standing only a few feet high within the
church. There is, alas, nothing to tell us about the clock it was
intended to house; most probably it was a water clock similar to that of
the illustrated Bible of _ca._ 1285.

The drawing of the rope, wheel and axles, for turning an angel to point
towards the sun can have a simple explanation or a more complicated one.
If taken at its face value the wheel on its horizontal axis acts as a
windlass connected by the counterpoised rope to the vertical shaft which
it turns, thereby moving (by hand) the figure of an angel (not shown)
fixed to the top of this latter shaft. Such an explanation was in fact
suggested by M. Quicherat,[38] who first called attention to the Villard
album and pointed out that a leaden angel existed in Chartres before the
fire there in 1836. It is a view also supported from another drawing in
the album which describes an eagle whose head is made to turn towards
the deacon when he reads the Gospel. Slight pressure on the tail of the
bird causes a similar rope mechanism to operate.

A quite different interpretation has been suggested by Fremont;[39] he
believes that the wheel may have acted as a fly-wheel and the ropes and
counterpoises, turning first one way then the other acted as a sort of
mechanical escapement. Such an arrangement is however mechanically
impossible without some complicated free-wheeling device between the
drive and the escapement, and its only effect would be to oscillate the
angel rapidly rather than turn it steadily. I believe that Fremont,
over-anxious to provide a protoescapement, has done too much violence to
the facts and turned away without good reason from the more simple and
reasonable explanation. It is nevertheless still possible to adopt this
simple interpretation and yet to have the system as part of a clock. If
the left-hand counterpoise, conveniently raised higher than that on the
right, is considered as a float fitting into a clepsydra jar, instead of
as a simple weight, one would have a very suitable automatic system for
turning the angel. On this explanation, the purpose of the wheel would
be merely to provide the manual adjustment necessary to set the angel
from time to time, compensating for irremediable inaccuracies of the
clepsydra.

[Illustration: Figure 21.--VILLARD'S PERPETUAL MOTION WHEEL, from Lassus
(see footnote