7i 



tCIEMTlFlC NEW*. 



b, a plate of lead, fastened to the bottom, to ballast the 

 cube, so as to float level with the surface. 



c c, knots from which proceeds a silk cord, forming an 

 acute angle at the point d. 



e, hook in the loop of the red cord about two yarrfs long, 

 tied to a green cord of ten yards, rolled up on the reel f, to 

 measure the velocity. 



g, a flat piece of hard wood forming a base to the reel, in 

 the centre of which is a small rod of polished steel, on 

 which, as an axis, the reel turns freely. 



A, tail of the catch, on which the thumb rests, to let the 

 reel move at the signal given. 



Fig. 4. i, a small dynarpometer, with an index, to mark on 

 the arch the maximum of the impulse of the current. 



Fig. 6. A, the log, floating in the stream. 



/, the observer in a boat, holding in his hand thedynamor 

 meter, to estimate the force of thp current, after having 

 measured the velocity. 



French Insti- 



SCIENTIFIC NEWS. 



French Institute, 



A.N analysis of the proceedings of the raathematical an4 



tuie. physical class, during the year 1309, by Mr. Delambre, 



perp. sec, has just reached us. 



„ , , „ Ihe question of the stability of the planetary system has 



Stability of the ^ , , . 4/r i i i 



planetary sys- been still farther pursued by Mr. Lagrange, who has exa- 



'*™' mined it in a more general point of view, extending it to a 



gystem of bodies acting on each other in any manner what- 

 ever. He also purposes to investigate the relation of the 

 planets round their centre of gravity, considering the devia- 

 tion of their figure from a sphere, and the attraction the 

 other p'aiiets exert on each of their particles. 

 _ . Mr. Poisfton, as a continuation of his inquiry on the ya- 



•hp Earth, nations of the elements of the planets, has composed a pa- 

 per on the rotation of the Earth. As Mr. Lagrange has 

 noticed the extreme difficulty of this problem, we cannot 



be 



