214 
POPULAR SCIENCE REVIEW. 
best features of the previous stands of Ross, Powell & Lealand, Ladd, and 
other makers. The Ross new patent object-glasses (devised by Mr. Wen- 
ham) are believed by the makers to have so well proved their superiority 
that they are now exclusively offered, and the old construction abandoned, 
from the half inch upwards/’ 
Microscopical Tapers of the Quarter.— The following papers have been 
published in the ^Monthly Microscopical Journal” for January, February, 
and March, 1875 : — 
On the Development of the Smaller Blood-vessels in the Human 
Embryo. By Dr. H. D. Schmidt, of New Orleans, U.S.A. — On 
Pigment-Flakes, Pigmentary Particles, and Pigment-Scales. By 
Joseph Gr. Richardson, M.D., Microscopist to the Pennsjdvania Hospital. 
— On a Modification of the “ Slit ” for Testing Angle. By R. B„ 
Tolies, Boston, U.S.A. — On Some Male Rotifers. By C. T. Hudson, 
LL.D. — On the Invisibility of Minute Refracting Bodies caused by 
Excess of Aperture, and upon the Development of Black Aperture 
Test-bands and Diffraction Rings. By Dr. Royston-Piggott, M.A., 
F.R.S., &c. — On Bog Mosses. By R. Braitkwaite, M.D., F.L.S., &c. — 
On the Similarity between the Red Blood-corpuscles of Man and those 
of certain other Mammals, especially the Dog ; considered in connection 
with the Diagnosis of Blood Stains in Criminal Cases. By Dr. J. J. 
Woodward, U.S. Army. — A New Illuminating Apparatus for the 
Microscope. By Professor E. Abbe, of Jena. — The President’s Address 
to the Royal Microscopical Society. — Studies in the Natural History of 
the Urates. By W. M. Ord, M.B. Bond., Senior Assistant-Physician 
to St. Thomas’s Hospital. — Certain Fungi Parasitic on Plants. By 
Thomas Taylor, Microscopist of the United States’ Department of 
Agriculture, Washington, D.C., U.S.A. 
PHYSICS. 
A New Instrument for Multiplying Small Motions. — This is the subject 
of a paper which was lately read before the Physical Society by Mr. G. F_ 
Redwell. The instrument consists of a train of multiplying wheels, the 
first of which is moved by the body whose elongation is to be determined, 
while the teeth of the last engage with the threads of an endless screw, 
whose axis is vertical, and carries at its upper extremity a long index moving 
over a graduated circle. 
Apparatus for showing Internal Tesistance in Battery Cells. — Professor 
Macleod read a paper on this subject before the Physical Society. TwO' 
tubes about half a metre long, and one of which is twice the diameter 
of the other, are closed at their lower ends with corks. On the corks and 
within the tubes rest two discs of platinum foil, connected with binding- 
screws by platinum wires passing through the corks. The platinum plates 
are covered with small quantities of chloride of silver, and the tubes are 
filled with n solution of chloride of zinc. Each tube is provided with a 
disc of amalgamated zinc soldered to a long copper wire, which is well 
