tracing stylus
41Vertometer — A vertometer is an ophthalmic bench instrument used to measure dioptric power of a lens. It differs from a lensmeter or lensometer which is a general dispensary tool for opticians to verify spectacle prescriptions at the laboratory. A vertometer …
42Roller printing on textiles — Roller printing, also called cylinder printing or machine printing, on fabrics is a textile printing process patented by Thomas Bell of Scotland in 1783 in an attempt to reduce the cost of the earlier copperplate printing. This method was used in …
43Harold Innis's communications theories — Harold Adams Innis (November 5, 1894 ndash; November 8, 1952) was a professor of political economy at the University of Toronto and the author of seminal works on Canadian economic history and on media and communication theory. He helped develop… …
44Édouard-Léon Scott de Martinville — (25 April 1817 ndash; 26 April 1879) was a French printer and bookseller who lived in Paris. He invented the earliest known sound recording device, the phonautograph, which was patented on March 25, 1857, as French patent #17,897/31,470. [cite… …
45Harold Hopkins — Born 6 December 1918 Leicester UK Died 22 October 1994 Reading UK Nationality …
46kymograph — An obsolete instrument for recording wavelike motions or modulation, especially for recording variations in blood pressure; it consists of a drum usually revolved by clockwork and covered with smoked paper upon which the curve is inscribed by a… …
47Dora the Explorer (video game series) — Dora the Explorer video games are a series of games designed for preschoolers based on the 2000 Nick Jr. television show Dora the Explorer. Contents 1 Game titles 2 Development 3 Reception 4 …
48Draped Bust dollar — Bust Dollar United States Value 1.00 U.S. dollars Mass  26.96 g Diameter  39–40 mm Edge Lettered …
49Duane H. Cooper — (1923, Gibson City Illinois, April 4, 1995) was a physicist, who made early investigations regarding the intricate geometry of the phonograph stylus groove interface. He earned a Bachelor of Science and Ph.D. degree with honors in physics in 1950 …
50Einthoven , Willem — (1860–1927) Dutch physiologist Einthoven, the son of a physician, was born at Semarang on the Indonesian island of Java and educated at the University of Utrecht in the Netherlands, where he gained his MD in 1885. In the following year he moved… …
