A'P P E N D I X II. 37

hived' it in a different Form from that inVhich they are usually made, and by whichCleans they are easily applicable to the fore-going Purposes; and even those that willfttew Jupiter's Moons are hereby renderedPortable, or adapted to the Pocket.

These Pocket Reflecting Telescopes havea Drawer, in the End of which the smallspeculum is fixed, and adjusted by Teetha nd Pinion. They are equally applicableto use at Sea as at Land; and, notwith-ftanding many People have been persuaded,that Refracting Telescopes are most use-hst at Sea, the Absurdity of this Notionhist evidently appear to any one who con-siders what we have in the foregoing Lec-ture sufficiently demonstrated, viz. Thatthe natural Cause of indistinct Vision isv astly less in a Reflecting Telescope thana Refractor; and this upon the Suppo-htion that the Quantity of Light and mag-nifying Power are the fame in both. Toc °nclude, I am thoroughly satisfied that ifthe Nature of this Instrument was well con-sidered and understood, and People couldhe made ready at the Use of it, they whoc °uld afford to purchase it, would neverhave any other. Rut though the practi-Cft l Application be very easy, yet as it isB b 2 new