'410 PHILOSOPHICAL TRANSACTIONS. [aNNO 166Q, 



country thereabout : but upon restoring the waters all have liberty to fish ; and 

 the fishermen, standing up to the waist at the holes before-mentioned, inter- 

 cept the passage of the fish, and take a very great number of them, which 

 otherwise would be secure for some months under the earth, and not fail to 

 return in September. The fish of this lake have a closer habitation than those 

 of any other I know ; for they pass some months under the earth, and a good 

 part of the winter under ice. But beside these holes at the bottom of the 

 lake, there are also divers caverns and deep places in the country of Carniola, 

 even where there is no water ; like those in the Peak Country, and at Elden- 

 hole in England. 



An Account of some Books. N" 54, p. 1086. 



I. Mechanica, sive de Motu Tractatus Geometricus. Auth. Joh. Wallis, 

 SS. Th. D. et Geom. Profess. Saviliano, &c. 1670, in 4to. 



In the first part of this work are delivered the general laws of motion. Se- 

 condly, the descent of heavy bodies by gravity. Thirdly, the doctrine of the 

 lever or balance, containing the fundamental principles of all statics ; in which 

 the author explains the geometrical considerations requisite in making both ex- 

 act common scales, and the Roman s^tera. On this part of the lever depends 

 the whole doctrine of the centre of gravity, and the calculation thereof; showing 

 how by calculation to assign it, in all sorts of lines, surfaces, solids, as well 

 such as are bounded, or take their rise from curved lines_, as those that are 

 bounded by straight lines and plains. 



And from the general principles here laid down in his third part (which is to 

 follow) he derives the doctrine of the lever, the pulley, the screw, the axis 

 in peritrochio, or several sorts of wheel-work ; and other such mechanical en- 

 gines derived from these. As likewise the doctrine of percussion (on which 

 depends that of the cuneus or wedge, with many other speculations of a like 

 kind) : and that of resilition or rebounding, which (as appears by a short spe- 

 cimen formerly printed in Numb. 43 of these Tracts) he derives from a reper- 

 cussion, either of some other body in motion which it meets with, or from the 

 elastic force or spring in one or both of the meeting bodies, which being com- 

 pressed by the collision, endeavour to restore itself by repelling these bodies one 

 or both ways. 



II. Nathan Highmori * de Hysterica et Hypochondriaca Passione, Responsio 

 Epist. ad Doct. Willis. Lond. 1670, 4to. 



* See p. 271 of this vol. of our Abridgement. . 



