



Produced by Jon Niehof, Don Kretz, Juliet Sutherland, Charles Franks
and the DP Team





[Illustration]




SCIENTIFIC AMERICAN SUPPLEMENT NO. 446




NEW YORK, JULY 19, 1884

Scientific American Supplement. Vol. XVIII, No. 446.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.


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TABLE OF CONTENTS

I.    CHEMISTRY.--Tin in Canned Foods.--By Prof. ATTFIELU.--Small
      amount of tin found.--Whence come these small particles.--No
      cause for alarm.

II.   ENGINEERING AND MECHANICS.--The Windmill.--By JAMES
      W. HILL.--The Eclipse wind.--Other wind mills.--Their operation,
      use, etc.

      The Pneumatic Dynamite Gun.--With engraving of pneumatic
      dynamite gun torpedo vessel.

      Rope Pulley Friction Brake.--3 figures.

      Wire Rope Towage.--Treating of the system of towage by hauling
      in a submerged wire rope as used on the River Rhine, boats
      employed, etc.--With engraving of wire rope tug boat.

      Improved Hay Rope Machine.--With engraving.

      The Anglesea Bridge, Cork.--With engraving.

      Portable Railways.--By M DECAUVILLE.--Narrow gauge roads
      in Great Britain.--M. Decauvilie's system.--Railways used at the
      Panama Canal, in Tunis, etc.

III.  TECHNOLOGY.--Improved Pneumatic Filtering Presses, and the
      Processes in which they are employed.--2 engravings.

      Pneumatic Malting.

      A New Form of Gas Washer.--Manner in which it is used.--By
      A. BANDSEPT.--2 figures.

IV.   ELECTRICITY, HEAT, ETC.--Gerard's Alternating Current
      Machine.--2 engravings.

      Automatic Fast Speed Telegraphy.--By THEO. F. TAYLOR.--Speed
      determined by resistance and static capacity.--Experiments
      Taylor's system.--With diagram.

      Theory of the Action of the Carbon Microphone.--What is it?
      --2 figures.

      The Dembinski Telephone Transmitter.--3 figures.

      New Gas Lighters.--Electric lighters.--3 engravings.

      Distribution of Heat which is developed by Forging.

V.    ARCHITECTURE, ART. ETC.--Villa at Dorking.--An engraving.

      Arm Chair in the Louvre Collection.

VI.   GEOLOGY.--The Deposition of Ores.--By J.S. NEWBERRY.--Mineral
      Veins.--Bedded veins.--Theories of ore deposit.--Leaching
      of igneous rocks.

VII.  NATURAL HISTORY, ETC.--Habits of Burrowing Crayfishes
      in the U.S.--Form and size of the burrows and mounds.--Obtaining
      food.--Other species of crayfish.--3 figures.

      Our Servants, the Microbes.--What is a microbe?--Multiplication.
      --Formation of spores.--How they live.--Different groups
      of bacteria.--Their services.

VIII. HORTICULTURE.--A New Stove Climber.--_(Ipomaea thomsoniana)_

      Sprouting of Palm Seeds.

      History of Wheat.

IX.   MISCELLANEOUS.--Technical Education in America.--Branches
      of study most prominent in schools of different States.

      The Anaesthetics of Jugglers.--Fakirs of the Indies.--Processes
      employed by them.--Anaesthetic plants.

      Epitaphium Chymicum.--An epitaph written by Dr. GODFREY.

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IMPROVED FILTER PRESSES.


Hitherto it has been found that of all the appliances and methods for
separating the liquid from the solid matters, whether it is in the case
of effluents from tanneries and other manufactories, or the ocherous and
muddy sludges taken from the settling tanks in mines, some of which
contain from 90 to 95 per cent. of water, the filter press is the best
and the most economical, and it is to this particular process that
Messrs. Johnson's exhibits at the Health Exhibition, London, chiefly
relate. Our engravings are from _The Engineer_. A filter press consists
of a number of narrow cells of cast iron, shown in Figs. 3 and 4, held
together in a suitable frame, the interior frames being provided with
drainage surfaces communicating with outlets at the bottom, and covered
with a filtering medium, which is generally cloth or paper. The interior
of the cells so built up are in direct communication with each other, or
with a common channel for the introduction of the matter to be filtered,
and as the only exit is through the cloth or paper, the solid portion is
kept back while the liquid passes through and escapes by the drainage
surfaces to the outlets. The cells