392 Foreign Literature and Science. 



He found that magnetism was produced in a needle, fixed 

 in the axis of a glass cylinder or bottle of eight inches, and 

 even of thirteen i-^ches in diameter, surrounded by a spiral. 

 He contrived to turn a metallic wire into a spiral of seven 

 feet in diameter, and found that needles placed in the axis 

 were slightly magnetised by strong discharges through the 

 spiral. Idem. 



Prof. Erman, of Berlin, has shown the connection be- 

 tween magnetism and voltaic electricity, in the following in- 

 genious way. In a silver or copper crucible he places a 

 watch glass, and in the glass a small mass of zinc. A strip 

 of zinc or of tin is fastened at one end to the mass of zinc, 

 and extending upwards and outwards over a pasteboard 

 band in which the cup rests, it is fastened at the other to the 

 cup itself. This forms a complete voltaic circuit, and the 

 current is estabhshed as soon as the cup is filled with acidu- 

 lated water. VV^hen the apparatus is suspended to a thread, 

 and a magnetic bar is brought near it, either an attraction or 

 a repulsion takes place, according to the direction of the 

 galvanic current in the apparatus and the magnetic current 

 in the bar. Bib. Univ. 



35. Estimafion of the mass of water which flows down 

 ike Rhine, at Bale. — The determination of this curious 

 problem has been undertaken with much address by M. 

 Escher, of Linth. The rise and fall of the water is ascer- 

 tained with sufficient precision by a Rhonometre. A sec- 

 tion of the bed of this river was obtained by measurement, 

 and the mean velocity of the water carefully determined. 

 The result is that the medium quantity of water which flow- 

 ed down the Rhine in one year, is 1,046,763,676 cubic 

 toises of 1000 feet each. 



To form an idea of this volume, the author supposes for 

 a moment a basin of fifteen leagues in length and five in 

 breadth ; for example, the lake of Constance. He found 

 that the flow of the Rhine in 1809, poured into that basin, 

 would raise it to the depth of fifty-six feet. If then the 

 lake of Constance were empty, it would require many 

 years for the Rhine at Basle to fill it, for the mean depth of 

 that lake, in all probability, greatly surpasses fifty-six feet. 



