Horseshoe to the modern hoof boot. Historians differ on the origin of the horseshoe. Because iron was a valuable commodity, and any worn out items were generally reforged and reused, it is difficult to locate clear archaeological evidence. Although some credit the Druids, there is no hard evidence to support this claim. In 1897 four bronze horseshoes with what are apparently nail holes were found in an Etruscan tomb dated around 400 B.C. The assertion by some historians that the Romans invented the "mule shoes" sometime after 100 BC is supported by a reference by Catullus who died in 54 BC.
Types of trombone used. Instead of three valves in the style of the trumpet, it has one for each position on the trombone slide. This unusual variation of the trombone has both a slide and valves. Different types of valve-slide trombone hybrid combinations were first manufactured in the early 20th century. One of the best known early types was the "valide trombone" invented by jazz trombonist and reedist Brad Gowans, which featured a slide on the inside on the valves which did not lock, forcing the player to actively use both hands. The most popular valve-slide trombone combination today is the "superbone", which