277 



On these principles, the author thinks it will readily appear why 

 the various attempts hitherto made to divert the motion of the shin- 

 gles to a distance from the general line of the shore, both at Dover 

 and at Folkstone, have invariably failed ; and he recommends, for 

 the prevention of the evil of accumulation, the adoption of a more 

 general system of management along the coast, in preference to the 

 resorting to particular devices adapted exclusively to each particular 

 case. 



The reading of a paper, entitled, " On some Elementary Laws of 

 Electricity." By W. Snow Harris, Esq., F.R.S. — was commenced. 



April 17, 1834. 

 FRANCIS BAILY, Esq., Vice-President, in the Chair. 

 The reading of Mr. Harris's paper was resumed in continuation. 



April 24, 1834. 



DAVIES GILBERT, Esq., D.C.L., Vice-President, in the Chair. 



The reading of Mr. Harris's paper was concluded. 



For the purpose of determining several questions relative to the 

 forces exerted by bodies in different states of electricity, the author 

 contrived an electroscope of peculiar construction, and also an elec- 

 trometer, both of which he minutely describes j and in order to ob- 

 tain a unit of measure, in estimating the quantity of electrical accumu- 

 lation, instead of transmitting the electricity evolved by the machine 

 immediately from its conductor to the battery to be charged, he inter- 

 poses between them a coated jar, furnished with a discharging elec- 

 trometer, so that the quantity of charges that have passed through it 

 may be estimated by the number of explosions occurring in the pro- 

 cess of accumulation. By increasing or diminishing the distance be- 

 tween the discharging balls, the value of the unit may at pleasure be 

 rendered great or small. 



A series of experiments is described, showing that when a given 

 quantity of electricity is divided among any number of perfectly simi- 

 lar conductors, the attractive force, as measured by the electrometer, 

 is inversely as the square of that number 3 and if different quantities 

 of electricity be communicated to the same conductor, their attractive 

 forces are directly as the squares of those quantities. 



The author observes that the electrical force exerted by one body 

 on another is always diminished by the vicinity of a neutral body ; 

 an effect which is analogous to the operation of screens in diminish- 

 ing the force of a revolving magnet on metallic disks, as noticed by 

 him in a former paper, published in the Philosophical Transactions. 

 It appears, thus, that there is, in all these cases, a portion of elec- 

 tricity, which is masked, and not appreciable by the electrometer. 



x 2 



