(741)
Numb. 38.
PHILOSOPHICAL
TRANSACTIONS.
Monday, August 17. 1668.
The Contents.
A Contrivance to make the Picture of any thing appear on a Wall, Cup-board, or within a Picture-frame, &c. in the midst of a Light room in the Day-times; or in the Night-time in any room that is inlightned with a considerable number of Candles. An Extract of a Letter, written from Leiden by Mr. Sam. Colepress to the Publisher, about the making of counterfeited Opal, and the Recovery of the Art making Red-glass. Some Animadversions written in a Letter by Dr John Wallis to a printed Paper entituled, Responsio Francisci Du Laurens ad Epistolam D. Wallisii ad Cl. Oldenburgium scriptam. An Account of two Books. I. REGNERI de GRAEF Med. D. De VIRORUM ORGANIS GENERATIONI INSERVIENTIBUS. II. LOGARITHMOTECHNIA NICOLAI MERCATORIS: discoursed of in a letter written by Dr. J. Wallis to the Lord Vis-count Brouncker; at whose desire the same Doctor in another Letter demonstrates his Method of Finding the Summ of Logarithmes. To which is added Mr. Mercatois illustration of his said Logarithmotechnia.
A Contrivance
To make the Picture of anything appear on a Wall, Cub-board, or within a Picture-frame, &c. in the midst of a Light room in the day-time; or in the Night-time in any room that is enlightned with a considerable number of Candles; devised and communicated by the lngenious Mr. Hook, as follows;
THis Optical Experiment, here to be described, is New, though easy and obvious; and hath not, that I know, been ever made by any other person this way. It produces Effects not
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