[Sidenote: _Doctrine of circular motions._] Of later years there succeeded new inventions, and horologies composed by Trochilick or the artifice of wheels; whereof some are kept in motion by weight, others perform without it. Now as one age instructs another, and time that brings all things to ruin, perfects also every thing; so are these indeed of more general and ready use then any that went before them. By the Water-glasses the account was not regular: for from attenuation and condensation, whereby that Element is altered, the hours were shorter in hot weather then in cold, and in Summer then in Winter. As for Scioterical Dials, whether of the Sun or Moon, they are only of use in the actual radiation of those Luminaries, and are of little advantage unto those inhabitants, which for many months enjoy not the Lustre of the Sun. It is I confess no easie wonder how the horometry of Antiquity discovered not this Artifice, how _Architas_ that contrived the moving Dove, or rather the _Helicosophie_ of _Archimedes_, fell not upon this way. Surely as in many things, so in this particular, the present age hath far surpassed Antiquity; whose ingenuity hath been so bold not only to proceed below the account of minutes, but to attempt perpetual motions, and engines whose revolutions (could their substance answer the design) might out-last the exemplary mobility, and out measure time it self. For such a one is that mentioned by _John Dee_, whose words are these in his learned Preface unto _Euclide_: By Wheels strange works and incredible are done: A wondrous example was seen in my time in a certain Instrument, which by the Inventer and Artificer was sold for twenty talents of gold; and then by chance had received some injury, and one _Janellus_ of _Cremona_ did mend the same, and presented it unto the Emperor _Charles_ the fift. _Jeronimus Cardanus_ can be my witness, that therein was one Wheel that moved at such a rate, that in seven thousand years his own period should be finished; a thing almost incredible, but how far I keep within my bounds, many men yet alive can tell. CHAPTER XIX Of the Pictures of _Mermaids_, _Unicorns_, and some others.