72 Intelligence and Miscellaneous Articles. 



of turns of the coil ; the resistance increases, and the intensity is 

 diminished. The opposite effect is produced if the intensity of the 

 current diminishes. 



By suitably regulating the force of the antagonizing spring, the 

 electromagnet, the distribution of the wire upon the bobbin, and 

 the curvature of the divider, we can render the system astatic ; and 

 then the apparatus gives a mathematically constant current. 



In practice we can maintain the intensity of the current between 

 two limits fixed beforehand, and as close as we will. 



Prom an industrial point of view, the apparatus can be applied 

 to electrotyping, to the incandescence of wires of platinum or 

 iridium (to prevent their fusion), and, if the problem should one 

 day receive its practical solution, to the distribution of electricity 

 in dwelling-houses, where the apparatus will play the part of a 

 real meter and divider of the electric current. — Oomptes Mendus cle 

 V Academic des Sciences, Dec. 9, 1878, t. lxxxvii. p. 920. 



ON THE PHYSICAL STATE OF CENTRAL EUEOPE IN THE TERTIARY 

 PERIOD (AS DISPLAYED IN THE WRITINGS OF PROF. 0. HEER). 

 BY M. VAN TIEGHEM. 



By publishing, iu 1828, his Histoire des Vegetauoc fossiles, M. 

 Ad. Brongniart laid the foundation of vegetable palaeontology. 

 Having a few years afterwards, about 1835, entered upon the new 

 path, M. Oswald Heer was not long in gaining therein one of the 

 highest ranks, which he has been able to keep. 



The study of the plants, and also of the insects, of the Tertiary 

 formations had till then been much neglected ; and it was to these 

 that Prof. Heer almost exclusively devoted the fine series of in- 

 vestigations which he indefatigably pursued for more than forty 

 years. 



By a great number of special memoirs, published in succession 

 from 1836 to 1858, he applied himself first to making known the 

 plants and insects observed in the three horizons of the Miocene 

 in different localities in Switzerland. Among the local floras and 

 faunas thus established, unquestionably the richest, and also the 

 most instructive, is that of the lignites of (Eningen, belonging to 

 the Upper Miocene, and comprising 475 species of plants. Having 

 accomplished this, he compared and coordinated the rich material 

 thus acquired for science in two great works forming a whole : — 

 the Faune des Insectes tertiaires, of which I have not to speak here ; 

 and the Flore tertiaire de la Suisse, in which are described, figured, 

 and classified 920 species of fossil plants, of which 700 were new. 



A little later, completing his investigation of the Miocene plants 

 of Switzerland, extending his researches to the vegetables of all the 

 tertiary formations of Europe, and adding the results obtained 

 respecting the plants of the same age found in the other regions 

 of the globe, he endeavoured to reconstruct the world of which 

 those creatures formed a part, and gave us his grand work entitled 

 Recherches sur le Climat et la Vegetation du Pays tertiaire, a French 



