196 Sheldon — Magneto-optical Generation of Electricity. 



15' and 40° 30'. The sections, as exhibited on the plate accom- 

 panying the article, indicate that the uplifting force, besides 

 flexing the beds, made a series of faults in the formations, and 

 that these faults were upthrust faults of blocks that included 

 the Archaean with the overlying rocks ; that the upthrust was 

 in general westward. The disturbed region shades off east- 

 ward into the horizontal strata of the great plains. For 

 descriptions of the beds, and of the echelon character of the 

 flexures (a feature first mentioned, the author says, by Hayden 

 in his report of 1869) reference may be made to Mr. Marvine's 

 report. The volumes of the survey of the 40th Parallel con- 

 tain other facts on the subject, which are discussed by Mr. 

 King. 



The observations prove that although the Front Range, or 

 the eastern branch of the Protaxis, greatly exceeds in height 

 the western, the uplifts adjoining it were very small. This 

 high Front Range stands within the wide area of Mesozoic de- 

 positiofi, within the area therefore of Mesozoic subsidence; 

 while the line of the Wasatch and the protaxis in British 

 America is to the west of this area and outside of it ; and 

 this may be a reason for the feeble orographic effects at its base. 



Art. XXIII. — The Magneto-optical Generation of 'Electricity y 

 by Samuel Sheldon, Ph.D. 



While experimenting upon the effects of alternating cur- 

 rents of electricity upon the plane of polarized light, results 

 were obtained which made it feasible to try a series of experi- 

 ments, in which the Faraday arrangements were reversed. 

 Although the series is incomplete, yet the little that has been 

 accomplished seems worthy of publication. 



It is well known* that if a beam of plane polarized light be 

 passed through a tube containing bisulphide of carbon, and if 

 the tube and beam lie in the direction of the lines of force of 

 an electromagnet about to be excited, the plane of the emer- 

 gent beam will be rotated upon exciting the magnet. The 

 direction of rotation will be the same as that of the exciting 

 current and the amount ' of rotation will depend upon the 

 strength of the current. If the current be reversed the plane 

 will be rotated in an opposite direction and by exactly the 

 same amount. Thus the rapidly alternating current would 

 produce a rapid swinging to and fro of the plane of light. 



* Faraday, Exp. Res. 2146, vol. iii, p. 1. 



