VI.  MISCELLANEOUS.—­Coal in the Argentine Republic.—­Note.

      History of the World’s Postal Service.—­Conclusion of this
      interesting article.—­The service in Germany, China.  Russia, and
      elsewhere.—­10 illustrations.

      Snow Hall—­The new science and natural history building of the
      University of Kansas.

VII.  Naval engineering.—­Improvement in Laying Out Frames
      of Vessels.—­The Frame Placer.—­By Gustave Sonnenburg.—­Ingenious
      apparatus for use in ship yards.—­1 illustration.

      Sea-going Torpedo Boats.—­The inutility of small torpedo boats
      at sea.—­The construction of larger ones discussed.

VIII.  Ordnance.—­Firing Trial of the 1101/2 Ton B.L.  Elswick Gun. 
      Full dimensions of this piece and it projectiles.—­Results of proof
      firing.—­9 illustrations.

IX.  Photography.—­Experiments in Toning Gelatino-Chloride
      Paper.—­Trials of ten different gold toning baths, formulas,
      and results.

      Printing Lantern Pictures by Artificial Light on Bromide Plates
      from Various Sizes.—­By A. Pumphrey.—­The processor producing
      smaller or larger transparencies from negatives.—­1 illustration.

X. PHYSICS.—­A New Mercury Pump.—­Simple air pump for high vacua.—­1 illustration.

      The Laws of the Absorption of Light in Crystals.—­By H.
      Becquerel.

      Varying Cylindrical Lens.—­By Tempest Anderson, M.D.,
      B. Sc.—­Combination of two conoidal lenses.—­Range of power obtained.

XI.  Physiology.—­Elimination of Poisons.—­Treatment of poison
      cases by establishment of a strong diuresis. 
      The Filtration and the Secretion Theories.—­Experiments on the
      action of and secretions of the kidneys.

XII.  Technology.—­Furnace for Decomposing Chloride of Magnesium.—­Furnace
      with rotating chamber for use by alkali manufacturers.—­1
      illustration.

      Notes on Garment Dyeing.—­The production of blacks on silk and
      wool.—­Formulas for mordants.

      Studies in Pyrotechny.—­II.  Methods of Illumination.—­Continuation
      of this valuable treatise.—­9 illustrations.

      The “Sensim” Preparing Box.—­New machine for treatment of
      fiber.—­An improvement on the ordinary gill box.—­3 illustrations.

* * * * *

THE RETIRO VIADUCT.

We give engravings of the viaduct over the river Retiro, Brazil, our illustrations being reproduced by permission from the Proceedings of the Institution of Civil Engineers.  In a “selected paper” contributed to the volume of these proceedings just published, Mr. Jorge Rademaker Grunewald, Memb.  Inst.  C.E., describes the work as follows: