VOL. II.] PHILOSOPHICAL TRANSACTIONS. ^6^ 



III. Michaelis Angeli Ricci* Exercitatio Geometrica; in 4to. printed at 

 Rome. 



This book is reprinted in London, and annexed to Logarithmotechnia N. 

 Mercatoris. It was thought fit to be so reprinted, partly by reason of its scarce- 

 ness, but chiefly by reason of the excellency of the argument, which is, de 

 maximis et minimis, or the doctrine of limits ; wherein, according to the ac- 

 count of the intelligent Mr. John Collins, the author shows a deep judgment 

 in discovering a medium to reduce the lately found out analytical doctrine de 

 maximis et minimis to pure geometry. The tract itself is very small, being lit- 

 tle more than two sheets of paper ; wherein is demonstrated the doctrine of Ca- 

 ravagio de applicationibus, who affirms, that he who is ignorant therein may 

 mispend his time about equations, in searching for that which cannot be found. 

 He delivers also a method of drawing tangents to all the conic sections, and di - 

 vers other curves. 



IV. La Venerie Royale du Sig. de Salnove, in 4to. a Paris. 

 Treating of the different kinds of hunting in France. 



u4 Contrivance to make the Picture of any Thing appear on a ffall, &c. 

 in a Light Room. By Mr. Hook. N" 38, p. 741. 



This optical experiment is new, though easy and obvious ; and has not that I 

 know been ever made by any other person in this way. It produces effects not 

 only very delightful, but to such as know not the contrivance very wonderful ; 

 so that spectators not well versed in optics, that should see the various appari- 

 tions and disappearances, the motions, changes and actions, that may this way 

 be represented, would readily believe them to be supernatural and miraculous. 



Opposite to the place or wall where the apparition is to be, let a hole be made 

 of about a foot in diameter or larger ; if there be a high window that has a case- 

 ment in it, it will be so much the better. Without this hole place the picture 

 or object, which you will represent, inverted, and by means of looking-glasses 

 set behind, if the picture be transparent, reflect the rays of the sun so as that 

 they may pass through it towards the place where it is to be represented; and 

 let the picture be encompassed on every side with a board or cloth, that no rays 

 may pass beside it. If the object be a statue or some living creature, then it 

 must be very much enlightened, by casting the sun beams on it by refraction, 

 reflexion, or both. Between this object and the place where it is to be repre- 



■* Michael Angelo Ricci was a learned Italian divine, born at Rome, l6l9. He was well skilled 

 in the pure mathematical sciences, of which the above article is a good specimen. He was created 

 cardinal in 168I 5 but did not long enjoy that dignity, dying in l683, iX6^ years of age. 



