Intelligence and Miscellaneous Articles. 69 



I have also deduced from my formula this conclusion — that if 

 the greatst oblateness sometimes attributed to Mars be admitted, 

 we must conclude that its surface- density is greater than the inte- 

 rior density of the planet ; but as such a conclusion seems to me to 

 be contrary to the laws of Physics, if the constitution of Mars be 

 like that of the Earth, until more complete observations shall 

 have been made, I prefer accepting the conclusions of Bessel, 

 Johnson, Oudemans, and Winnecke, who admit an almost insensible 

 oblateness for Mars. 



An extract from my previous researches on the theory of the 

 form of the Earth as a result of attrition appeared in several scien- 

 tific journals some years ago ; I am sure, however, that the results 

 got by M. Amigues were obtained in a manner altogether indepen- 

 dent of, and without his having had any knowledge of my investi- 

 gations. 



The entire agreement of his calculations with those I had pre- 

 viously made is not only interesting as far as regards Mars, but they 

 confirm the idea I had formerly upheld in opposition to the theory 

 of Playfair, Herschel, and Lyell, on the form and structure of the 

 Earth. — Comptes Eendus de VAcademie des Sciences, No. 17, Oct. 22, 

 1878. 



ON A NEW PHENOMENON OF STATIC ELECTRICITY. 

 BY E. DUTER. 



I have the honour of submitting to the Academy the description 

 of an experiment which proves that, in certain cases, electrization 

 changes the volume of bodies. 



In order to make the experiment, we procure a large thermo- 

 meter-case. With this we make a condenser of which it is the 

 insulator by passing into its interior a platinum wire, filling it 

 with water, and pasting to its outer surface a sheet of tinfoil. "We 

 have thus a Ley den jar, which we charge by the usual methods. 

 As soon as it receives the charge the surface of the water is seen to 

 sink, remain stationary as long as the charge continues, and in- 

 stantly resumes its former level with the discharge. As in a con- 

 denser the electricity resides only in the insulator, it is natural to 

 conclude from this experiment that the glass dilates. We obtain a 

 first confirmation of this idea on remarking that, whatever may be 

 the nature of the armatures — tinfoil, water, saline solutions, or 

 mercury — the same apparent contraction of the liquid inside is ob- 

 served. To remove all doubt, I modified the apparatus by putting 

 the Leyden jar into a closed glass case, terminated also with a ther- 

 mometric stem, and likewise filled with a conducting liquid. In 

 this arrangement the liquid of the inner reservoir forms the internal 

 armature of the condenser, the liquid in the case forms the external 

 armature, and the surface of the inner glass is the insulator. It is 

 this which, if our previsions are correct, should be enlarged by the 

 electrization. We find, in fact, that the water descends in the ther- 

 mometric tube of the inner vessel, and a sensibly equal quantity 

 ascends in the measuring-tube of the outer case. As soon as the 



