114 TRANSACTIONS OF THE [APR. 6, 
tion of the outcrop remaining at 144th street and Seventh ave- 
nue. He remarks on the resemblance of the rock to the Manay- 
unk schists of Hall, and suggests that it be examined. 
I went up there and obtained photographs and specimens, and 
noted the following. The strata, of gray gneiss, are mueh con- 
torted and show anumber of synclinals, a large one, in the centre 
of the outcrop, being of a compact gneiss in which feldspar pre- 
dominates. Scattered through the rock are segregated veins 
of pegmatite, while cutting directly across the strata, with a dip 
of 30° W., is a vein of granite. ‘This vein may be seen on the 
south end of the outcrop, and also on the north side of 144th 
street. 
At 143d street and Seventh avenue is an outcrop of a dark- 
colored, fine-grained mica schist. This outcrop also contains 
several granite veins, cutting across the strata, and one of them 
being branched. ‘These two rock outcrops are thus specially 
interesting on account of these veins, which seem to be injected 
rather than segregated ones, with the exception of the pegma- 
tite veins previously mentioned. The outcrops do not, as sug- 
gested by Mr. Rand, throw any further light upon the question 
of the exact geological age of the rocks of Manhattan Island. 
The following papers were read by W. Gooutp LeEvIson: 
I. NOTE ON AN ECONOMICAL ZINC ELEMENT FOR BUNSEN 
BATTERIES, 
illustrated by apparatus. 
This modification consists in using a number of zinc plates 
clamped to a brass collar by set screws. It is claimed that by 
this means greater surface and consequently greater efficiency 
is gained. If one or more plates are used up, new ones may 
be inserted with ease, and need not interrupt the action of the 
apparatus. 
Il. NOTE ON PHOTOMICROGRAPHS FROM PHOTOGRAPHS OF 
LIGHTNING, 
illustrated by lantern slides. 
