Prof. Maskelyne and Dr. Lang's Mineralogical Notes. 145 



maximum of the evening. But there is this difference, that 

 while the maximum of the morning is the principal in the cur- 

 rent, it is only the secondary in statical electricity. 



The general conclusion to be drawn from all this is, that the 

 variations in the currents of magnetized bars and of atmospheric 

 electricity may be derived from the same principle in motion ; that 

 this action cannot be confounded with that of solar heating ; and 

 that rather a kind of diurnal electrical flux and reflux must be 

 assumed allied to the solar action, but whose energy in this 

 transformation is manifested in a different manner to that of 

 direct heat and light. The opinion already enunciated by M. 

 De la Rive, that the different variations of magnetized bars may 

 be derived from the atmospheric electricity, appears thus to ac- 

 quire great probability. 



I shall conclude with a word on the extraordinary magnetic 

 variations. Observations made during the 7th, 8th, 9th, and 

 10th of June, when there was a great magnetic disturbance, have 

 once more shown that these motions of the bars are connected 

 with motions of the currents ; but a profound discussion cannot 

 find a place here. I may, however, simply remark that the 

 existence of irregular earth currents in telegraphic wires has 

 become to M. Jacobini a very marked sign of approaching bad 

 weather and surrounding storms; and I think this might be 

 utilized in other telegraphic lines for predicting the weather. 

 This is also a new and unsought-for confirmation of the con- 

 nexion between storms and magnetic variations. 



XVI. Mineralogical Notes. By Professor N. S. Maskelyne 



and Dr. Viktor von Lang, of the British Museum. 



[With a Plate.] 



[Continued from vol. xxvi. p. 139.] 



On some Combinations of Gadolinite. By Viktor von Lang. 



THE researches of A. E. Nordenskjold* and Th. Scheererf 

 have shown that the crystals of Gadolinite belong to the 

 prismatic system. To the same conclusion I was led by the 

 examination of the specimens of Gadolinite in the mineralogical 

 collection of the British Museum, although several of the crystals 

 I examined were of a decidedly oblique habit. But as we find 

 that on such apparently oblique crystals sometimes the longer, 

 sometimes the shorter diagonal of the prism comes to simulate 

 the axis of symmetry, we are justified in considering that fact 

 only another proof of the prismatic character of these crystals. 



* Ofversigt. afKongl. Vetenskap Akademiens Forhandlingar, 1 859, No. 7> 

 p. 287. 



t Neues Jahrbuchfiir Min. &c. 1861, p. 134. 

 Phil. Mag. S. 4. Vol. 28. No. 187. Aug. 1864. L 



