THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



DECEMBER 1859. 



LXII. On Atmospheric Electricity. By F. Dellmann*. 



THE complete account of the results of the observations on 

 atmospheric electricity, instituted at this meteorological 

 station (Kreutznach) by the command of the government upwards 

 of a year ago, will be found in the second Jahresbericht des 

 Konigl. meteorologischen Institutes which will appear in the 

 course of the present year (1853). We must hei'e limit our- 

 selves to a description of the apparatus and method of observa- 

 tion, together with a summary of the results. 



It was clearly pi'oved by Duprez in his essay, Sur I'electridte 

 de Fair, to which the Academy of Brussels awarded a prize in 

 1844, that, in consequence of imperfect insulation, no fixed appa- 

 ratus, such as that lately proposed by Dr. Romershausen, can 

 ever indicate in a trustworthy manner the true electric condition 

 of the atmosphere. The truth of this assertion has been placed 

 beyond all doubt by the experiments undertaken at this obser- 

 vatory; at the same time two other imperfections inseparable 

 from such an apparatus, and to which Duprez does not allude, 

 have manifested themselves : these are, first, that the apparatus 

 becomes charged too slowly, so that an electric condition of the 

 air is often indicated which, both quantitatively and qualitatively, 

 has long since ceased to exist; secondly, that the indications of 

 the apparatus do not represent correctly the condition of the 



* From Poggendorff's Annalen, vol. Ixxxix. 1853, p. 258. 



In the 15th Volume of the Phil. Mag. (p. 4()0j, Professor W. Thomson 

 communicated a short article from Dellmann, " On the Observation of At- 

 mospheric Electricity." The present memoir enters into more details with 

 respect to the a|)paratus, and to the results of the observations made at 

 Kreutznach in 185.3. The former article, on the contrary, contains a more 

 detailed description of the measurer or electrometer, and will consequently 

 be sometimes referred to. — Transl. 



Phil. Mag. S. 4. Vol. 18. No. 122. Dec. 1859. 2D 



