I. ENGINEERING AND MECHANICS.—­Bridge over the Blaauw Krantz Ravine, Cape Colony.—­2 engravings.

     Torpedo Ships.

     The Gas Engine.—­By Dugald Clerk.—­Combustion engines.—­First
     cylinder and piston engine.—­Watt’s experiments.—­First gas
     engine.—­Principles of the gas engine.

     Rapid Construction of the Canadian Pacific Railway.—­By E.T. 
     Abbott.

     The Osgood Mammoth Excavator.—­3 figures.

     Capstan Navigation on the Volga.—­4 figures.

     Steamboat Equipment of War Vessels.—­With engraving of winch
     for raising and lowering torpedo boats.

     Improved Steam Trap.—­1 engraving.

II.  TECHNOLOGY.—­Critical Methods of Detecting Errors in Plane Surfaces.—­By JOHN A. BRASHEAR.—­11 figures.

     Photometric Standards.—­9 figures.

     Bleaching or Dyeing Yarns and Goods in Vacuo.—­1 figure.

     On the Moulding of Porcelain.—­By Chas. Lauth.—­Moulding by
     pressure of the air.—­Moulding by vacuum.—­Drying the moulded
     pieces.—­2 figures.

     Photo-Tricycle Apparatus.—­1 figure.

     A Photo Printing Light.—­1 figure.

     A New Actinometer.

     Astronomical Photography.

     Electricity as a Preventive of Scale in Boilers.

III.  DECORATIVE ART.—­Alphabet designed by Godfrey Sykes.—­An engraving.

     Old Wrought Iron Gate.—­An engraving.

IV.  Geology.—­The Organization and Plan of the United States
     Geological Survey.—­By J.W.  Powell.—­A topographic map
     of the United States.—­Paleontology.—­Chemistry.—­Physical
     researches.—­Statist
ics.—­Library.—­Publications.—­General
     geology.—­Economic geology.—­Relation of the general survey
     to the State survey.

V. BOTANY, ETC.—­The Sunflowers.—­Annuals, perennials, etc.—­11 engravings.

     Lye’s Fuchsias.—­1 engraving.

VI.  HYGIENE, ETC.—­Brief Sanitary Matters in Connection with Isolated Country Houses.—­By E.W.  BOWDITCH.

     Sanitary Cooking.—­By V.L.  Oppenheimer.

     Time required to digest Different Foods.

* * * * *

THE BLAAUW KRANTZ VIADUCT IN CAPE COLONY.

This viaduct is built over a rocky ravine on the railway from Port Alfred to Grahamstown, at a height of about 200 ft. from the bottom.  Its length is 480 ft. 6 in., and the width of the platform is 15 ft., the gauge of the railway being 3 ft. 6 in.  The central span of the viaduct is an arch of 220 ft. span between abutments, and about 90 ft. height; the remainder of the space on each side is divided into two spans by an iron pier at a distance of 68 ft. from the retaining wall.  These piers are 36 ft. 2 in. high, and carry girders 144 ft. long, balanced each on a pivot in the center.  One end of these girders is secured to the retaining walls by means of horizontal and vertical anchorages, while the other end rests in a sliding bearing on the top flange of the arch.