666 PHILOSOPHICAL TRANSACTIONS. [anNO I67I, 



stitution indifferently, but is raised, as we see bread in baking, into a congeries 

 of fixed bubbles; the parenchyma of the whole seed being such. 



II. Dissertations sur la Nature du Froid et du Chaud ; par le Sieur Petit, 

 Conseiller du Roi, Intendant des Fortifications, &c. Avec un Discours sur la 

 Construction et I'Usage d'un Cylindre Arithmetique, invente par le meme 

 Auteur. AParis, 1 67 1. 



The famous author of these two tracts, examines in the former, first, the 

 nature, subject, cause, and effects of cold. As to its nature, he considers it a 

 positive thing, and not a mere privation, the effects of it being as sensible to us 

 as those of heat. For the subject of it, he places the supreme cold in the pure 

 air, and makes the heat, that is sometimes in the air, merely adventitious, pro- 

 duced in it by the sun, but the cold natural to the same. Concerning the cause 

 of this cold in the air, he will not acknowledge it to be nitre, all sorts of salt 

 being by him esteemed hot, much less an universal spirit, or any stars ; but 

 esteems, that the air is the primum frigidum by nature; the same cause, that has 

 made it air, having made it cold. 



Secondly, he discourses of fire, after he has discarded it from being one of 

 the common four elements, and dislodged it from its reputed place above the 

 air under the concave of the moon : And affirms, that it is the heat of the sun, 

 which moves, quickens, and coagulates the three families of mixts, animals, 

 vegetables and minerals, yet taking in a subterraneous heat for the production 

 of minerals. 



In the latter part of this book, the author explains an invention of his, the 

 arithmetical cylinder. This is a contrivance for making arithmetical calculations 

 after the manner of Napier's rods. Instead of these, the author writes the 

 numbers on narrow slips of paper, pasted lengthwise on a cylinder of wood or 

 pasteboard, having some small knobs on the surface, by means of which the 

 cylinder is turned round, and thus the arithmetical calculation is performed. 



III. La Dioptrique Oculaire, par le Pere Cherubin* d'Orleans, Capucin. 

 A Paris, 1671, in fol. 



The author of this large and elegant volume, having proposed to himself to 

 comprehend in it and to teach all that concerns the theory, use, and mechanism 

 of the telescope (by him called the ocular dioptrique,) divides it into three prin- 

 cipal parts. 



The first contains the doctrine of optics and dioptrics, or of simple vision 



* The father Chembin was author also of another optical work, named. La Vision Parfaite, in 

 * volumes folio. An. l677 and 168I. He took great pains to recommend the use of the Binocular 

 telescope, or one to look tlurough with botli eyes at oncej which however has fallen into dis- 

 use. 



