( 74 1 ) 
PHILOSOPHICAL 
TRANSACTIONS. 
Mooday 5 Auguft 17. 166$. 
Tlie Contents. 
A Contrivance to make the Figure ef any thing appear on a Wall^ 
Cup-board^ or within a Picture- frame, &c. in the midfi of a 
Light room in the Day-time $ or in the Night- time in any room 
that is inlightned with a con fider able number of Candles , An 
BxtracJ of a Letter ^ written from Leiden by Mr. Sam, Cole- 
prefsta the Publijher, about the making of counterfeited Opal, 
and the Recovery of the Jrt of making Red- glafs. Seme Am- 
madverfions written in a Letter by Dr John Wallis to a printed 
Paper entituled > Refponfio Francifci Du Laurens ad Epifto- 
Jam D, Wallifii ad CI. Oldenburgium fcriptam. An Ac* 
count of two Books . I, REGNERI de GRAEF Med, D. De 
VIRORUM ORGANIS GENERATION! INSERFIENTl- 
BUS. if. LOG A RITHMOTECHNIA N1COLAI MER- 
CATORIS: difcourfed of in a letter written by Dr. J. Wallis 
to the Lord Vif count Brooncker- at whofede fire the fame Do- 
dor in another Letter demonstrates his Method of Finding the 
Summ of Logarithmes, To which is added Mr. Mercators it- 
lu fir at ion of his faid Logarithmotechnia. 
, A Contrivance 
To make the Piclvre of any thing appear on a Wall, . Cub-board, or 
within a Pitfure-irame^ drc. in the mid/l of a Light room in the 
day-time 5 or in the Night-time in any room that is enlightned 
with a confidcrable number of Candles 5 devifed and communi- 
cated by the Ingenious Mr. Hook 3 as follows $ 
THisoptical Experiment.here to be defcribed.is New.thouefi 
eafy and obvious 5 and hath not, that I know, been ever 
made, by any other perfoa this way. It produces Eflfeds not 
Nnnn Gn ]y 
