114 Scientific Intelligence. 
tive above. 5°25’, A similar point still observable, but about 5° 
nearer the horizon 
arch 12th, gb 30’, a.m. Cloudy. Polarization positive from East 
and West horizon, nearly to Zenith. A similar observation was made 
March 21st, at 69 p.m. 
March 17th, 9h and 10" 40/ a.m.,? and March 18, 10° 30’, a.m.° 
Very clear. Sun so bright that I was unable to detect the negative 
polarity between Babinet ts neutral ae . Brewster’s, even by screen- 
ing the eye from i sah light of the 
Mare vie, ll A.M." Halo, visible only through the polariscope. 
tet 20th, vig 25’, p.m. Cloudy. Polarization in horizon every- 
where pos 
March oath to 28th, inclusive. On each of these five successive days . 
Brewster’s neutral point was remarkably distinct and beauti ul. 
April 3d, 5" 40’ p.m. Cloudy in West, and polarization positive from 
iti to hori rizon. 
trong reflection sometimes changes the character of a comparatively 
weak polarization, from positive to negative, or vice versd. A fal inter 
reflection, by showing whether the bands are interrupted or continuous, / 
often gee in determining the character of the polarization. 
reased refraction of a piece of glass, interposed between the 
polavidcope and the sky, will frequently show a neutral point which is 
otherwise invisible. 
The normal polarity is often reversed by, a stratum of clouds of uni- 
form thickness, especially within the solar primary lemniscate. 
II. MINERALOGY AND GEOLOGY. 
1. On the age of the gold-bearing rocks of the Pacific Oe by Prof. 
Wa. H. Brewer. (Communicated for this bdo al). —In t he preceding 
number of this Journal, in a résumé o tney’s “Geology of Cali- 
fornia,” I noticed in some detail (pp. 361-3 64 ,) the ee aed oe data from 
which the secondary age of the auriferous rocks of the Paci ast had 
their first publication. These ee ae a reference to the more important 
fossils that had come under the observation of the members of the 
en datoren 
Since that aie was printed, a paper bearing about the same date 
has been Bes Net entitled, 
? On steamboat in Raritan es. * At Eagleswood, near Perth Amboy- 
4 In New Yo rk, : ra 
ae 
7 
