- 
484 Scientific Intelligence. 
oe satisfactory explanation of _ remarkable effect, which so far 
m being intentional on the part of the manufacturers of the mir- 
rors, appears to have been =, unknown to the Japanese, al- 
though known to the Chinese from the earliest times. It appeared 
tern was invisible; 3, w ‘en the beam was convergent the pattern 
appeared a s dark ona light ground. These and similar experi- 
ments exhibited by the lecturer all point to the — o- 
of the 
gwo 0 et ee per cent of the ordinary Japanese bronze mirrors 
show the magic neopiee clearly. 
II. GEoLoGY AND MINERALOGY. 
1. The Cincinnati Group.—A committee was recently ees 
by the Cincinnati Society of Natural History to consider “que 
indicate the age 5b the Utica Slate Goons of New York. A fauna 
is represented in these rocks that is not found above or seis 
th Within this range we find the - Triarthus Beckii, tia 
Byrnesi, obolus lepis, Buthotrephis ramulosa, and several 
eee: of Graptolites, Crinoids, Bryozoans na. ond Brachiopods, that 
m to be confi in its. 
ne 
Ot thon the range of the Zriarthus Baie the fossils, as w 
as the position of the rocks, indicate the age of the Hudson River 
ala of New York, and we have no hesitation in so referrin 
the entertain no doubt of the correctness of the reference. 
“Tn Southeastern Indiana neither the Trenton nor Utica slate 
pear, and, consequently, we refer all the Lower Silurian rocks 
f that State to the Hud n River Group. 
