376 MICROSCOPY. 
class of relics, found in the neighborhood of Trenton, New Jersey. 
So far as the writer’s experience in collecting goes, these hammer- 
stones are found away from the water, on the sites of villages, and 
more particularly on the sites of the operations of arrowhead 
akers. Curiously enough, too, the average weight of these ham- 
mer-stones is greater, as we have found them, than the average 
weight of those found at Muncy, Pennsylvania, by Mr. Rau. 
Always associated with the ordinary hammerstone, which is that 
with a depression on either side, for the ends of the thumb and 
second finger, is a smaller cylindrical hammer, of harder mineral, 
with nothing to indicate that it is a “relic,” other than the well 
battered ends, which are as well marked in these specimens, as the 
similar batterings and finger pits are in the typical hammer- 
stones. — CHARLES C. Assort, M. D. 
Antiquity or Man IN America. — In the December number of 
this Journal we made an abstract of a paper printed by the Phila- 
delphia Academy, in which Mr. Berthoud gave an account of 
the relics of an early race of men. As the geological position 
of the relics has been questioned, further information is very 
desirable. 
MICROSCOPY. 
A New Stipe ror rae Microscorr.—At a recent meeting of 
the Optical Section of the Franklin Institute, there was described 
and exhibited in operation a new adjunct to the microscope, de- 
signed by Mr. D. S. Holman, a member of the section, whose life 
slide recently attracted so much attention and comment. The 
new device may be called a current cell, or moist chamber, and is 
designed to afford the microscopist the opportunity of observing 
and studying the constitution of the blood and other organic fluids 
with much greater ease and precision than it has heretofore been 
found possible to attain. The accompanying illustration will 
serve to make the description of its construction and operation 
manifest: The slide consists of a plain piece of plate glass of 
considerable thickness, and three inches by one in dimensions. 
This is furnished at equal distances from its centre with two well 
polished shallow cavities of circular form, which are connected 
with each other by one or more capillary channels. These chan- 
nels are likewise polished, and to permit of a greater field in 
