Volume 1

Rohault's System of natural philosophy / illustrated with Dr. Samuel Clarke's notes taken mostly out of Sir Isaac Newton's philosophy. With additions [by R. Laughton and C. Morgan]. Done into English by John Clarke.

  • Rohault, Jacques, 1618-1672.
Date:
1723
Catalogue details

Licence: Public Domain Mark

Credit: Rohault's System of natural philosophy / illustrated with Dr. Samuel Clarke's notes taken mostly out of Sir Isaac Newton's philosophy. With additions [by R. Laughton and C. Morgan]. Done into English by John Clarke. Source: Wellcome Collection.

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    CHAP. XXXIII. Of DIOPTRICKS. I. That our Opinion a- bout Fiji on may be con¬ firmed by the Examination of different Sorts of Per- jpeftivc- Glaffes and Looking- Glaffes. z. Why an Objeci is mul¬ tiplied when lookedat thro‘ a multiplying- Glafs. Tab.VIII, IN order to prove the Truth of fome of thofe Suppo- fitions which we have made about Vifionj we ought now to confider, whether or no all thofe Things* which up¬ on thefe Suppofitions ought to come to pals* when we look through different Sorts of Perfpedtive-Glaftes or upon Looking-Glaffes, be agreeable to Experience, for this will be a great Proof of the Truth of thofe Sup¬ pofitions. 2. We will begin with Perfpedtive-Glafies* and firft let us confider that Sort called Multiplying~Gla]fes, fuch as that in the Figure ABCD. Now it is evident in the firft Place, that without this Glafs, the Eye E would fee the Objedt F, by means of the Rays which come from F to Gj and becaufe the Superficies BC is here parallel to the Superficies AD* which is oppofite to it* and there¬ fore the Refradtion which the Rays fuffer when they enter into the Glafs* is deftroyed by the Refradtion made at their coming out; it follows* that the Eye ought not¬ wit hftanding* to receive the Impreffion of the Objedt in the fame Place G* where it would have received it if there had been no Glafs* and for this Reafon it ought Rill to fee the Objedt in F. It is alfo certain* that the Object F, would make an Impreffion upon an Eye placed in N by the Rays which it would fend thither, if there were no Glafs between j but becaufe thefe Ray$ now meet with the Superficies AB, by which they are fo refradted* that when they come out of the Glafs, they enter into the Pupil of the Eye E, and afterwards go on in fuch a manner as to fail upon that Part of the Bottom of the Eye marked I* where they imprefs fuch an Image as an Object placed in M would do j therefore this caufes the Eye at the fame Time that it fees the Objedt F in its true Place, to fee it alfo in M. So likewife the Rays which would excite Vifion in the Eye* if it were placed in O, and no Perfpedtive-Glafs intervened* being in this Cafe refradted by the Super¬ ficies CD, fo as to imprefs an Image of the Objed F on the Part of the Eye marked H* where an Objedt placed