392 Scientific InfeUigence. [May, 



is charged. If we make one of these quanthies equal to zero, we 

 shall have the case where one of the spheres is electrified by the 

 sole influence of the other, and we well know the re-action of this 

 sphere upon the former. If it is the smallest sphere that is electri- 

 fied by the influence of the greatest, the electricity will diminish 

 upon the jrreatest to 67° 30' from the point nearest the little sphere, 

 and it will ihen increase to the point diametrically opposite. The 

 author points out the method of producing at pleasure a minimum 

 of this kind. He draws from his formulas several other conse- 

 quences equally curious, and which would deserve a new set of 

 experiments to demonstrate their truth to those that are unable to 

 follow iiis analysis. In the mean time what ought to give the 

 fullest confidence in the accuracy of this theory is its astonishing 

 agreement with all the experiments which M. Poisson could find in 

 the works of jjhilosopliers. 



We have said that the series cease to converge when the two 

 spheres are very near each other; but by means of his definite 

 integrals the author transforms them into other series, which, in 

 order to converge, require that the distance between the two spheres 

 be small. In this manner he determines what happens in the pro- 

 gi-essive approach of the two spheres before they touch each other, 

 and what may be observed when after having placed them in con- 

 tact they are again separated. The phenomena indicated by the 

 calculus are precisely those observed by Coulomb, and this agi'ee- 

 ment appears to furnish a confirmation of the theory of two fluids 

 at present somewhat hy])othetical. 



The case of two spheres leads to equations with variable differ- 

 ences, and with two independent variables. M. Poisson remarks 

 that this is the first time that an equation of this kind has presented 

 itself in the solution of a physical problem. This is a new proof 

 that analytical researches, which one would be tempted sometimes 

 to consider as simple objects of curiosity, ahvays at last find a useful 

 application. 



{To bs continued.) 



Article XI. 

 SCIENTIFIC intelligence; and notices of subjects 



CONNECTED WITH SCIENCE. 



I. Lectures. 



Mr. Joseph Hopkins, surgeon to his Royal Highness the Duke 

 of Kent, proposes to deliver a course of lectures on the theory and 

 practic? of midwifery, at the VVcstminstt^r Lying-in Institution. 

 The I'jctures are ii'ustrated with cases, and each pupil is to deliver 

 one patient every six days, beginning after he has attended the first 



