Thus, with the aid of this machine, solar and lunar eclipses of the past
can be recalled and future ones can be foreseen. Indeed, if the index of
prime minutes is speeded up by hand, whose wheel imparts motion to the
other indices and shields, then, the dials and openings will foretell
the year, month, day, hour, etc., of any future eclipse. I foresaw that
the times would thus be evolved too slowly, and that the clock wheels
would be considerably worn by repeated experiments (if, for instance, by
the rotation of the index of prime minutes, to whose period only a
single hour corresponds, the future new and full moon ecliptics were
being investigated). Therefore, I took care that the wheel which
immediately communicates motion to the index of the synodic moon should
be so fitted internally to the mechanism that by the reversal of any
external index, the wheel would be removed from its proper position;
whenever desired, it could be quickly and most accurately restored to
its proper place.
In this way, since the close meshing of the wheels is released, you can
extend the experiment for many years, even for many centuries. You have
only to guide with your hand the index of the synodic moon on the
circles, always intently observing whether, in the passage which this
index makes over the little index, both pointers of the little index are
hidden by the segments of the circle. Having observed this, look at the
index moved by hand, for if this has carried the solar disk halfway
between the two larger segments of the circle to the region of the
hidden little index, then you will know that eclipse will be a solar
eclipse. On the other hand, you will know that it will be a lunar
eclipse, if the index (moved by hand) has carried the moon, situated
between the two smaller segments of the circle, to the same region
(i.e., the hidden part of the circle). The solar disk and the lunar disk
alternately will reveal to you the circumstances of both eclipses. The
current year will be given by the Julian period, reducible to any
desired epoch, and, contained in the solar cycle, the golden number and
the Roman cycle. The month of the year and also the day of the month
will be indicated by the pointer of the little index, first on the right
side of the clock. And what I have said of future eclipses should be
equally understood of past eclipses, so long as the index, which can be
moved either way at will, is moved in reverse.
Finally, though 55 wheels were employed to carry so many dials, all are
driven by one source of power not exceeding the third part of a Germanic
hundred-weight which, suspended at the geometric height of five feet
(about the ordinary stature of a man), keeps the whole machine in
operation for a hundred days and more.
Although the machine repeats hours and quarter hours at will and,
consequently, the number of wheels and the rest of the apparatus
necessary for these functions is thereby increased, it has not grown to
an unwieldy size, however much one might erroneously imagine it to be.
It does not exceed the bulk of ordinary clocks hanging from a wall;
indeed, it scarcely equals these.
The entire machine, ready for operation, does not weigh more than 156
ounces, although it is made of steel or brass throughout and further
weighted with two bells and a rather large brass dial-plate.
Of course, there are many more things to be said, especially about the
mechanical structure of the wheels, but fearing to tire my kind reader
unduly by exceeding the bounds of a summary, I am forced to put an end,
though unwillingly, to this sufficiently shortened explanation of the
work. I have hope of giving satisfaction to many more when I shall have
communicated to the learned world another and completely new automatic
work, grander than this present one. It is already theoretically
completed in all its calculations, but still to be worked out
mechanically from the very beginning, if but God, thrice Best and
Greatest, bless the undertaking and mercifully grant life and health--to
whom be in, and from, and through all things, all honor and glory in
eternity and beyond.