Of Light and Colours. 299

placed any where above the Surface A R*in a Situation lower than would be other-wise possible,; and thus Objects which areinvisible may be render’d visible by the In-terposition of a denser Medium, as is wellknown by a common Experiment. On thisAccount it is that we fee the Sun and otherLuminaries, while they are yet below theHorizon, in a Morning before they rife,and in the Evening after they are set, bythe Refraction of the Atmosphere. Hencealso the Difference in the Diameters ofthe Horizontal Sun and Moon , and theire Uiptic Figure , by the greater Refrac-tion of the Rays coming from the lower

Limb.

Again; it follows, that if an Objecthe viewed which is part in one Mediumand part in another, as a Staff representedhy N E, it will not appear strait, but crooked;for if the Eye be in the rarer Medium, thehart of the Staff in the denser, CE, willhe refracted into the Line CF, and theWhole Staff will appear in the crooked FormNcf.

Hence also all Objects in a denser Me-<hnm appear raised or elevated above theirre al Situations: Thus the Part of the StaffLE is raised into the Situation CF; and

the