and war ships.--3 illustrations. 8954

Jet Propellers.--Hydraulic propulsion of vessels.--
Mathematical examination of this subject. 8951

IX. ORDNANCE.--The New Army Gun.--Description of the 8-inch
steel gun as manufactured at the West Point, N.Y.,
Foundry.--1 illustration. 8952

X. PHYSICS.--A New Thermo Regulator.--1 illustration. 8959

Cohesion and Cohesion Figures.--By WILLIAM ACKROYD,
F.I.C.--Laws of vortex rings examined, and relation of
solubility to cohesion. 8963

Pipette for taking the Density of Liquids.--Apparatus and
calculations for use.--1 illustration. 8959

XI. TECHNOLOGY.--Impurities in Photographic Chemicals, and
Tests for Same.--Table referred to in a paper read before
the Birmingham Photographic Society by G.M. Jones, M.P.S. 8957

Molasses, how made.--Work on Plantations Graphically
Described.* 8961

Optical errors and human mistakes.--By ERNST GUNDLACH.--On
the examination of optical glasses.--A paper read before
the Buffalo meeting of the A.A.A.S. 8963

Soap.--By HENRY LEFFMANN, Ph.D. 8962