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[Illustration]




SCIENTIFIC AMERICAN SUPPLEMENT NO. 822




NEW YORK, October 3, 1891

Scientific American Supplement. Vol. XXXII, No. 822.

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.    ANTHROPOLOGY.--The Study of Mankind.--A review of Prof.
      Max Muller's recent address before the British Association.  13141

II.   CHEMISTRY.--Standards and Methods for the Polarimetric
      Estimation of Sugars.--A U.S. internal revenue report on
      the titular subject.--2 illustrations.                       13138

      The Formation of Starch in Leaves.--An interesting
      examination into the physiological _role_ of leaves.--1
      illustration.                                                13138

      The Water Molecule.--By A. GANSWINDT.--A very interesting
      contribution to structural chemistry.                        13137

III.  CIVIL ENGINEERING.--Demolition of Rocks under Water
      without Explosives.--Lobnitz System.--By EDWARD S.
      CRAWLEY.--A method of removing rocks by combined
      dredging and ramming as applied on the Suez Canal.--3
      illustrations.                                               13128

IV.   ELECTRICITY.--Electrical Standards.--The English Board of
      Trade commission's standards of electrical measurements.     13129

      The London-Paris Telephone.--By W.H. PREECE,
      F.R.S.--Details of the telephone between London and
      Paris and its remarkable success.--6 illustrations.          13131

      The Manufacture of Phosphorus by Electricity.--A new
      industry based on dynamic electricity.--Full details.        13132

      The Two or Three Phase Alternating Current Systems.--By
      CARL HERING.--A new industrial development in electricity
      fully described and graphically developed.--15
      illustrations.                                               13130

V.    GEOGRAPHY AND EXPLORATION.--The Grand Falls of
      Labrador.--The Bowdoin College exploring expedition and
      its adventures and discoveries in Labrador.                  13140

VI.   MECHANICAL ENGINEERING.--Improved Changeable Speed
      Gearing.--An ingenious method of obtaining different speeds
      at will from a single driving shaft.--2 illustrations.       13129

      Progress in Engineering.--Notes on the progress of the last
      decade.                                                      13129

VII.  MEDICINE AND HYGIENE.--Eyesight.--Its Care during Infancy
      and Youth.--By L. WEBSTER FOX, M.D.--A very timely
      article on the preservation of sight and its deterioration
      among civilized people.                                      13135

      The Use of Compressed Air in Conjunction with Medicinal
      Solutions in the Treatment of Nervous and Mental
      Affections.--By J. LEONARD CORNING.--The enhancement of
      the effects of remedies by subsequent application of
      compressed air.                                              13134

VIII. MINERALOGY.--A Gem-Bearing Granite Vein in Western
      Connecticut.--By L.P. GRATACAP.--A most interesting
      mineral fissure yielding mica and gems recently opened.      13141

IX.   NATURAL HISTORY.--Ants.--By RUTH WARD KAHN.--An
      interesting presentation of the economy of ants.             13140

X.    NAVAL ENGINEERING.--Armor Plating on Battleships--France
      and Great Britain.--A comparison of the protective systems
      of the French and English navies.--5 illustrations.          13127

      The Redoutable.--An important member of the French
      Mediterranean fleet described and illustrated.--1
      illustration.                                                13127

XI.   TECHNOLOGY.--New Bleaching Apparatus.--A newly invented
      apparatus for bleaching pulp.--2 illustrations.              13133

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THE REDOUTABLE.


The central battery and barbette ship Redoutable, illustrated this
week, forms part of the French Mediterranean squadron, and although
launched as early as 1876 is still one of its most powerful ships.
Below are some of the principal dimensions and particulars of this
ironclad:

    Length           318 ft. 2 in.
    Beam              64 "   8 "
    Draught           25 "   6 "
    Displacement    9200 tons.
    Crew             706 officers and men.

[Illustration: THE FRENCH CENTRAL BATTERY IRONCLAD REDOUTABLE.]

The Redoutable is built partly of iron and partly of steel and is
similar in many respects to the ironclads Devastation and Courbet of
the same fleet, although rather smaller. She is completely belted with
14 in. armor, with a 15 in. backing, and has the central battery
armored with plates of 91/2 in. in thickness.

The engines are two in number, horizontal, and of the compound two
cylinder type, developing a horse power of 6,071, which on the trial
trip gave a speed of 14.66 knots per hour. Five