A reply to Mr. Robin's remarks on the Essay upon distinct and indistinct vision published at the end of Dr. Smith's Complete system of optiks / by James Jurin.
- James Jurin
- Date:
- 1739
Licence: Public Domain Mark
Credit: A reply to Mr. Robin's remarks on the Essay upon distinct and indistinct vision published at the end of Dr. Smith's Complete system of optiks / by James Jurin. Source: Wellcome Collection.
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![t [ *7 ] Proposition I. • ^ :V.' ; ' i 1 < The change of difpofition in a ray of light, to be at one time eafily reflected, and at another time to be eafily tranfmitted, cannot be inftan- taneous, but like all other operations of nature, muft be made paulatim and by degrees. Proposition II. \ ) « '1 In every interval between two fits of eafy tranfmiffion, there is one point at which the dif¬ pofition of the ray to be reflected is the ftrongeft, and this point is precifely in the middle of the interval, as alfo in the middle of the fit of eafy • reflexion. And in every interval between two fits of eafy reflexion there is a like point, which is in the middle of the fit of eafy tranfmiffioh. t ■ 1 *\ Proposition III. (•_ x / * * jr ,•« V While the ray is approaching this middle point of the fit of eafy reflexion, its difpofition to be refledted grows ftronger and ftronger by certain degrees; and when the ray has palled this point, and is receding from it, that difpofition grows weaker and weaker by the fame degrees. And the like may be faid of the difpofition to be eafi¬ ly tranfmitted. For inftance, if the line A E A E reprefent part of the progrefs of a ray of light, in which the intervals A E, EA, A E are all equal; and A be the point at which the ray is moll ftrong- ]y difpofed to be tranfmitted, E the point at which it is moll ftrongly difpofed to be refiedted, D i. e.](https://iiif.wellcomecollection.org/image/b30780287_0025.jp2/full/800%2C/0/default.jpg)
