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IOJSs

SSSa

M'. Samuel Foster

|precepts,

CONCERNING

REFRACTED DIALS.

He Suns beames are refracted by anytransparent body that they fallupon. If the fame be more dense,or more thin and rare then theMedium through which they firstshine. Such bodies are either Solidsor Liquid : in both which kinds themost common bodies are, Glasie, orChristal, and Water-Refractions (as we are here to use them) may be diversWaycs considered. First, in Solid bodies, the superficies re-fracting may be either Plain, or Curved, and this either trulyregular, such as is Spherical, or such like; Or else various, ofno determinate regular form. And likewise the plain espe-cially (but the other also in some fort) may be either Hori-zontal : or otherwise placed, upright,or leaning.

Again , In Solids Pellucid, the raycs of the Sun from thepoint of an Index standing without side the Pellucid be-tween the Sun and it must passe , either first from the Indexthrough the Aire, and then into the Solid, and so meetingwith an opacous body , those joyned to the out-side of thetransparent body , may there be terminated, and so luster j

(a) but!

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