290 ATMOSPHERIC ELECTRICITY. 



EEPORT 



ON 



ATMOSPHERIC ELECTRICITY. 



BY M. F. DUTREZ. 



Translated for the Smithsonian Institution from the Memoirs of the Eo3-al Academy of 

 Brussels, by Dr. L. D. Gale. 



[This article is, perhaps, the best digest of the history of the observa- 

 tions and researches relative to the electricity of the atmosphere which 

 has ever been compiled, and therefore forms a proper addition to the 

 reports of Miiller on other parts of the general subject of electricity 

 which have been given in the appendix to the annual reports of the 

 Regents of the Smithsonian Insti-tution.] 



MEMOIR ON THE ELECTRICITY OF THE AIR. 



PART I. 



THE MEANS USED TO JUDGE OF THE ELECTRICAL PHENOMENA WHICH TAKE 

 PLACE IN THE ATMOSPHERE. 



On the construction of the first electrical machine the observers 

 were struck with the resemblance between the eifects of electricity and 

 those of lightning; scarcely had the first electric spark been perceived 

 when Wall;, Gilbert, and Grey compared its light to that of lightning. 

 This resemblance was still more clearly marked when the discovery of 

 the Leyden phial enabled philosophers to produce with electricity the 

 most astonishing effects of lightning. To render the identity perfect, 

 nothing remained but to collect the electricity which was supposed to 

 exist in the atmosphere. Two methods have been employed for this 

 purpose, one consisting of stationary apparatus, the other of movable 

 ones. In the former case, upright insulated rods or metallic wires, 

 also insulated and stretched in the air, have been used; in the latter, 

 kites, portable electrometers and rheometers are employed. These 

 diflerent articles of apparatus serve to collect the electricity of the air 

 in clear and cloudy weather, during fogs, rain, snow, and hail, and 

 finally in storms. 



CHAPTER I. 



OF ELECTRO-ATMOSPHERIC APPARATUS. 



§1. 0/ s!ationar}j apparatus. — Stationary apparatus was especially 

 used in the earlier periods when atmospheric electricity engaged the 

 attention. To Franklin* we are indebted for the first idea, and to 

 Dalibard,t a French physicist for the first verification, by experiment, 



* Experiments and Ohteervations on Electricity, made at Philadelphia, p. 6C; Loudon, 1769. 

 fid., p. 106. 



