80 Intelligence and Miscellaneous Articles. 



But a slight additional rotation will show that the neutralization is 

 only apparent. 



8. The position of a true neutral point can be determined by 

 sweeping its neighbourhood alternately with the vertical and with 

 the horizontal bands, and marking the intersection of the lines of va- 

 nishing polarization. 



9. In consequence of the arrangement of the lines of equal polari- 

 zation, when the sky is swept with a polariscope for a few degrees on 

 each side of a neutral point, the line which separates the oppositely 

 polarized bands forms curves with a convexity determined by the 

 position of the sun or the antisolar point*. 



10. Some of my observations have indicated an apparent corre- 

 lation between these curves and the magnetic dip and terrestrial 

 latitude. I have not been able to satisfy myself whether this corre- 

 spondence was merely accidental, or whether it indicated another 

 point of analogy between the laws of light and magnetism. 



1 1 . The varying effects of haze or cloud appear, on the whole, 

 to confirm Brewster's theory that the neutral point is produced " by 

 the opposite action of light polarized by reflexion and refraction." 

 (See pp. 123, 169, 176, 178, 180.) 



12. In one instance, soon after sunset, the reflexion from scat- 

 tered clouds in the neighbourhood of the antisolar point was such as 

 to totally eclipse Arago's neutral point, the polarization being posi- 

 tive over the entire arch, from Babinet's neutral point to the eastern 

 horizon. — Proceedings of the American Philosophical Society, vol. x. 

 January 5, 1866. 



ON MOTION IN A RESISTING MEDIUM. 

 BY DR. O. SCHRECK OF BREMEN. 



A series of experiments were made by filling a tall vessel with 

 water, and allowing bodies to fall in it. From the space fallen 

 through and the time occupied, an approximate conclusion could be 

 drawn as to the resistance of the liquid. The results are as follows : — 



(1) With velocities up to 20 centimetres the resistance is propor- 

 tional to the square of the velocity. 



(2) With greater velocities it is proportional to a higher power of 

 the velocity, which increases with the increase of the resisting 

 surface. 



(3) The resistance to spheres is approximately proportional to 

 the square of the diameter of the sphere, but, with larger spheres, 

 increases with the diameter in a continually increasing ratio. 



T (4) The resistances to spheres and cylinders of the same diameter 

 are as 2 : 3. 



(5) A cone experiences greater resistance than a sphere of the 

 same diameter. — Poggendorff's Annalen, April 1866. 



* I am not aware whether this is the " singular effect " thus described 

 by Brewster (loc. cit. p. 124) : — " In carrying the bands vertically round, 

 the neutral line, in place of crossing them at a right angle, was the arc of 

 a circle, to which one of the bands was a tangent.''* (See also pp. 121, 1670 



