Electric Welding--Elihu Thompson, United States, 1886.

Electric Waves discovered by experiment--Heinrich Hertz, Germany, 1888.

Coherer for receiving electric Waves--Edward Branly, France, 1890.

X-rays--Discovered by Prof. W. C. Roentgen, Germany; announced to the public in 1895.

Wireless telegraphy--G. Marconi, Italy, 1896.

Nernst electric light, a clay capable of conducting electricity when heated is used; it becomes incandescent without a vacuum--Walter Nernst, Germany, 1897.

Radium discovered by Madame Curie, France, 1898.

Explosives

Gunpowder--Inventor and date unknown.

Guncotton--Schonbein, Germany, 1845.

Nitroglycerine--Sobrero, 1847.

Explosive gelatine--A. n.o.bel, France, 1863.

Dynamite--A. n.o.bel, France, 1866.

Smokeless powder--Vielle, France, 1866.

Firearms and Ordnance

Spirally grooved rifle barrel--Koster, England, 1620.

Breech-loading shot-gun--Thornton and Hall, United States, 1811.

The revolver; a device "for combining a number of long barrels so as to rotate upon a spindle by the act of c.o.c.king the hammer"--Samuel Colt, United States, 1836.

Breech gun-lock, interrupted thread--Chambers, United States, 1849.

Magazine gun--Walter Hunt, United States, 1849.

Breech-loading rifle--Maynard, United States, 1851.

Iron-clad floating batteries first used in Crimean War--1855.

Breech-loading ordnance--Wright and Gould, United States, 1858.

Revolving turret for floating batteries--Theodore Timby, United States, 1862.

First iron-clad floating battery propelled by steam: the _Monitor_--John Ericsson, United States, 1862.

Gatling gun--Dr. R. J. Gatling, United States, 1862.

Automatic sh.e.l.l-ejector for revolver--W. C. Dodge, United States, 1865.

Torpedo--Whitehead, United States, 1866.

Disappearing gun-carriage--Moncrief, England, 1868.

Rebounding gun-lock--L. Hailer, United States, 1870.

Magazine rifle--Lee, United States, 1879.

Hammerless gun--Greener, United States, 1880.

Gun silencer, to be attached to barrel of gun; gun can be fired without noise--Maxim, 1909.

Gas Used for Light and Power

Gas first used for illuminating purposes--William Murdoch, England, 1792.

First street gas-lighting in England--F. A. Winsor, 1814.

Gas-meter--S. Clegg, England, 1815.

Water-gas, prepared by pa.s.sing steam over white-hot anthracite coal--First produced in England in 1823.

Illuminating water-gas--Lowe, United States, 1875.

Gas-engine, 4-cycle, beginning of modern gas-engine--Otto and Langen, Germany, 1877.

Incandescent gas-mantle--Carl A. von Welsbach, Austria, 1887.

Iron and Steel

Blast-furnace, beginning of iron industry--Belgium, 1340.

Use of c.o.ke in blast-furnace--Abram Darby, England, about 1720.

Puddling iron--Henry Cort, England, 1783-84.

Process of making malleable-iron castings--Lucas, England, 1804.

Hot-air blast for iron furnaces--J. B. Neilson, Scotland, 1828.

The galvanizing of iron--Henry Craufurd, England, 1837.