1860.] cm Atmospheric Electricity. 287 



balance the influence on the higher parts of the tower of more distant 

 positively electrified aerial masses. 



A long continuation of such systems of simultaneous observation — 

 not in a town only, but in various situations of flat and of mountainous 

 country, on the sea coast as well as far inland, in various regions of the 

 world — will be required to obtain the information asked for in the 

 second part of this question. 



Q. 3. Do the particles of rain, hail, and snow in falling through 

 the air possess absolute charges of electricity? and if so, whether 

 positive or negative, and of what amounts in different conditions as to 

 place and weather? Attempts to answer this question have been 

 made by various observers, but as yet without success ; as for instance 

 by an " electro-pluviometer," tried at Kew many years ago. By 

 using a suflSciently well insulated vessel to collect the falling particles, 

 it is quite certain that a decided answer may be obtained with ease 

 for the cases of hail and snow. Inductive effects produced by drops 

 splashing away from the collecting vessel, if exposed to the electric 

 force of the air in an open position, or inductive effects of the opposite 

 kind produced by drops splashing away from surrounding walls or 

 screens and falling into the collecting vessel, if not in an exposed 

 position, make it less easy to ascertain the electrical quality of rain ; 

 but, by taking means to obviate the disturbing effects of these influences, 

 the speaker hoped to arrive at definite results. 



It would have been more satisfactory to have been able to conclude 

 a discourse on atmospheric electricity otherwise than in questions, but 

 no other form of conclusion would have been at all consistent with the 

 present state of knowledge. 



The discourse was illustrated by the use of the mirror electrometer 

 reflecting a beam of light from the electric lamp, and throwing it on a 

 white screen, where its motions were measured by a divided scale. The 

 principle of the water-dropping collector was illustrated by allowing a 

 jet of water to flow by a fine nozzle into the middle of the lecture- 

 room, from an uninsulated metal vessel of water and compressed air, 

 and collecting the drops in an insulated vessel on the floor. This 

 vessel was connected with the testing electrode of the reflecting ^ctro- 

 meter ; and it was then found to experience a continually increasing 

 negative electrification, when fixed positively electrified bodies were in 

 the neighbourhood of the nozzle. If the same experiment were made 

 in ordinary fair weather in the open air, instead of under the roof and 

 within the walls of the lecture-room, the same result would be 

 observed, without the presence of any artificially electrified body. 

 The vessel from which the water was discharged was next insulated ; 

 and other circumstances remaining unvaried, it was shown that this 

 vessel became rapidly electrified to a certain degree of positive poten- 

 tial, and the falling drops ceased to communicate any more electricity 

 to the vessel in which they were gathered. 



The influence of electrified masses of air was illustrated by carry- 

 ing about the portable electrometer, with its match burning, to different 



