The Incomplete Combustion of Gases.--By H. B. Dixon.--Abstract of paper read before the British Association at Montreal. 7458 Aluminum and its Alloys. 7462 II. ENGINEERING AND MECHANICS.--The New Dam at Suresnes.--With engraving. 7453 Bréarey's Aeronautical Machine.--With engraving. 7453 Raising of the Fallen Girder of the Douarnenez Viaduct.--2 engravings. 7454 Improved Wire Testing Machine.--With engraving. 7454 Improved Doubling and Laying Machine.--With engraving. 7454 Boiler Tubes. 7455 Improved Ladle Carriage.--2 figures. 7455 The Repair of Boiler Tubes.--11 figures. 7455 Grulet's Screw for Raising Water.--1 engraving. 7456 III. TECHNOLOGY.--On Various Toning Baths.--Several experiments.--By W. M. ASHMAN. 7456 Coating Plates with Gelatine Emulsion.--5 figures. 7457 Iodo-chloride of Silver Emulsion.--By V. SCHUMANN 7458 Apparatus for Saturating Water with Sulphurous Acid.--1 engraving. 7458 IV. PHYSICS, ELECTRICITY. ETC.--The Wave Theory of Light.--By SIR WM. THOMSON.--Sound and light due to wave vibrations.--Difference between vibrations of light and sound.--Radiant heat.--Solar spectrum.--Luminiferous ether.--How to measure wave lengths of light and the frequency of vibrations.--With diagrams. 7448 The Limitations of Submarine Telegraphy. 7450 Williams' System of Coast Defense by Electrical Torpedoes.--Full page of figures. 7451 New Electric Gas Lighter.--2 figures. 7452 Insulators for Telegraph and Telephone Lines.--9 figures. 7452 Electric Light in Theaters. 7452 Rings of Smoke.--5 figures. 7461 V. ARCHITECTURE.--The New Technical High School at Berlin.--With engraving. 7447 The New University Buildings at Strassburg.--2 engravings. 7447 VI. BOTANY, ETC.--An Improved Hyacinth Glass. 7461 The Botanical Club of the American Association. 7461 VII. HYGIENE, MEDICINE, ETC.--Herbst's Method of Filling.--Demonstrated by Dr. G. C. CLUDINS. 7459 Dr. Koch's Berlin Lecture on Cholera and the Comma Bacillus. 7459 Local Anæsthesia by the Hydrochlorate of Cocaine.--By R. J. LEVIS, M.D. 7459