case-hardened steel
71Motor oil — For the TV documentary focused on the Edmonton Oilers of the National Hockey League, see Oil Change (TV Series). Motor oil sample Motor oil or engine oil is an oil used for lubrication of various internal combustion engines. The main function is… …
72Klerksdorp Spheres — The Klerksdorp Spheres are small, often spherical to disc shaped, objects, which have been collected by miners and rockhounds from 3.0 billion year old pyrophyllite deposits mined by Wonderstone Ltd., near Ottosdal, South Africa. These objects… …
73History of ferrous metallurgy — Iron (material) redirects here. For the chemical element Fe, see Iron. Bloomery smelting during the Middle Ages. The history of ferrous metallurgy began far back in prehistory. The earliest surviving iron artifacts, from the 5th millennium BC in… …
74gasoline engine — Most widely used form of internal combustion engine, found in most automobiles and many other vehicles. Gasoline engines vary significantly in size, weight per unit of power generated, and arrangement of components. The principal type is the… …
75Klerksdorp sphere — Klerksdorp spheres are small objects, often spherical to disc shaped, that have been collected by miners and rockhounds from 3 billion year old pyrophyllite deposits mined by Wonderstone Ltd., near Ottosdal, South Africa. They have been cited by… …
76A7V — Infobox Weapon|is vehicle=yes|name=A7V caption=A replica of Wotan in Panzermuseum Munster, Germany. type=tank origin= flagcountry|German Empire service= 21 March 1918 October 1918 used by= flagcountry|German Empire wars= World War I designer=… …
77Anti-tank rifle, model 35 — Infobox Weapon|is ranged=yes caption=Karabin przeciwpancerny wzór 35 name=Karabin przeciwpancerny wz.35 type=Anti tank rifle origin=flagcountry|Poland era=World War II design date= prod design date=1936 to 1939 serv design date=1939 used… …
78Emmet Sweeney — Emmet John Sweeney is a Scottish born historian, who has published a series of books arguing for a radical reconstruction of ancient history. He graduated from the University of Ulster, and has lectured at the West University in Timişoara,… …
79Mark I tank — A British Mark I male tank near Thiepval on 26 September 1916, fitted with wire mesh to deflect grenades and the initial steering tail, shown raised …
80Sheet metal — Sheets of stainless steel cover the Chrysler Building …
