A series of experiments relating to phosphori and the prismatic colours they are found to exhibit in the dark / by B. Wilson ... ; Together with a translation of two memoirs, from the Bologna Acts [1744 & 1747], upon the same subject, by J.B. Beccari.

  • Benjamin Wilson
Date:
1775
Catalogue details

Licence: Public Domain Mark

Credit: A series of experiments relating to phosphori and the prismatic colours they are found to exhibit in the dark / by B. Wilson ... ; Together with a translation of two memoirs, from the Bologna Acts [1744 & 1747], upon the same subject, by J.B. Beccari. Source: Wellcome Collection.

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    [3] The apparatus, employed by Beccari at firft, for bringing bodies fuddenly from the light into the dark, did'hot, as he acknowledges, anfwer the end required fo well as the fccond he made ufe of. I have had the fatisfadion of trying both me¬ thods, and found that the latter was, on many accounts, the more eligible, and better calculated for the purpofe. But as the duration of the phof- phoric light, mentioned by him, was fhorter con- iiderably than what I have obferved, I am inclined to think that one difference, at leaft, arofe from a difference in the degree of darknefs obtained, be¬ tween the*kind of box he made ufe of, and the fmall clofet I employed : the dimenlions^_oj[^ which- were about fix feet uy five and a hal^: and the heighth about nine feet. It was painted black, or covered with black baize in every part and had two doors that were five or fix inches broader and longer than the fpace to enter at. There were two curtains of black cloth over the hole where the hand was occa- fionally put out, to expofe bodies to the light; ' the outer one confifhed of three doubles, and the inner one of as many. All thefe were confiderably larger than the hole, which was about fifteen inches diameter, and opened to the South. There were fmall leaden weights faflened to the bottom of each curtain, to preferve them in their places when the hand was drawn into the room. And, that I might breathe the air freely, and continue longer in the clofet without any inconvenience, A 2 there
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