Letters on Natural Magic; Addressed to Sir Walter Scott, Bart

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David Sir Brewster. Letters on Natural Magic; Addressed to Sir Walter Scott, Bart

Letters on Natural Magic; Addressed to Sir Walter Scott, Bart

Table of Contents

LETTER I

LETTER II

LETTER III

LETTER IV

LETTER V

LETTER VI

LETTER VII

LETTER VIII

LETTER IX

LETTER X

LETTER XI

LETTER XII

LETTER XIII

General Descriptive Catalogue

ADDRESS

THE. FAMILY LIBRARY

FOOTNOTES:

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David Brewster

Published by Good Press, 2019

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In order to complete the history of the illusions which originate in the eye, it will be necessary to give some account of the phenomena called ocular spectra, or accidental colours. If we cut a figure out of red paper, and, placing it on a sheet of white paper, view it steadily for some seconds with one or both eyes fixed on a particular part of it, we shall observe the red colour to become less brilliant. If we then turn the eye from the red figure upon the white paper, we shall see a distinct green figure, which is the spectrum, or accidental colour of the red figure. With differently coloured figures we shall observe differently coloured spectra, as in the following table:—

The two last of these experiments, viz., white and black figures, may be satisfactorily made by using a white medallion on a dark ground, and a black profile figure. The spectrum of the former will be found to be black, and that of the latter white.

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