SB M. Van Swhiden on the l7i ve7itmn of Pendulum-Clocks 
the drawings’i I kept the copies sent' from 'Fiorence ; I had 
yours made after themv? {Leydeh M.^^.) r ; . : ! 
It' is hianifesty ffbnr inspection of the/: figure^ that 
Ihe drawing was made in: a Very coarse inatmer : I ^suppose, 
therefore, that the Ibwermbst ' wheel had teeth on its whole cir^ 
cumference, though but'orieihalf- is ■ represented^ and likewise 
that the nekt following or middle wheel was divided equally by 
teeth every where, though a part here consists of merely a few 
hasty strokes ; probabl;^ to iheet the convenience of : the artist 
who drew them . The axis to' which the pendulum is affixed , 
and which ihoved with it, has a short bent lever, reaching to 
a number of 'Studs or pins, projefcting from' the side of a sort of 
ratchet wheel; the teeth' or incisibns of which are equal in num- 
ber to the pins. Above ' this wheel appears a crooked lever, 
fixed at one end,’ on which it‘ turns, and seeming to rest with 
the other extremity against the axis or end of the pendulum, 
somewhat like a spring : it is also furnished with a projection, 
in the form of a cross, to enable it, as it would seem, to catch 
in its descent' the teeth of the wheel. Farther, there appears 
neither spring-barrel nor cylinder for a weight. The only indi- 
cation that can be found of its having been moved by a weight, 
is perhaps to be traced in the axis of the uppermost wheel, a 
part of which has an indistinct appearance of grooves cut into 
it, as if a rope or chain were to be wound round it. 
As to the Action of this machine, I can conceive the short 
bent lever to strike against one of the projecting pins, impelling 
it either iii the one direction or the other j whilst the pendulum 
is swinging to one side ; but I do not so easily perceive; the way 
in whichyoii swinging backwards, it should fall in with the next 
following pin ; and supposing this to be possible, then it is in- 
conceivable to me how the loss suffered by the pendulum in its 
passage through the air and' by friction, could be exactly cora- 
'pehsated, as happens in the clock of Huygens, by the reciprocal 
action of the crown-wheel on the pallets, a contrivance of great 
ingenuity, which was not at first clearly understood by all. 
Whether Vincenzio Galilei greatly improved upon the design 
of his father, is doubtful, for it is of his attempt in 1649 , that 
Prince Leopold and Frisi speak, when they call it a sketch 
riahozzo\^ Tiwd ,a slight shetch (?m poco (Tahozzo). But, however 
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