angle scale
71Greek arithmetic, geometry and harmonics: Thales to Plato — Ian Mueller INTRODUCTION: PROCLUS’ HISTORY OF GEOMETRY In a famous passage in Book VII of the Republic starting at Socrates proposes to inquire about the studies (mathēmata) needed to train the young people who will become leaders of the ideal… …
72Albedo — The albedo of an object is the extent to which it diffusely reflects light from the sun. It is therefore a more specific form of the term reflectivity. Albedo is defined asthe ratio of diffusely reflected to incident electromagnetic radiation. It …
73Map projection — A medieval depiction of the Ecumene (1482, Johannes Schnitzer, engraver), constructed after the coordinates in Ptolemy s Geography and using his second map projection A map projection is any method of representing the surface of a sphere or other …
74Ruler — For other uses, see Ruler (disambiguation). A variety of rulers A 2 meter …
75Grade (climbing) — Rock climbing History Styles Technique Equipment and protection Grades (difficulty of climb) Terminology Belaying Abseiling …
76Chisel — This article is about the tool. For the American band, see Chisel (band). For the album by Australian band Cold Chisel, see Chisel (album). Steel woodworking chisel …
77Saw — For other uses, see Saw (disambiguation). Saw A crosscut hand saw about 620 mm (24 inches) long Classification Cutting Types Hand saw Back saw Bow saw Circular saw …
78Octant (instrument) — Octant. This instrument, labelled Crichton London, Sold by J Berry, Aberdeen, appears to have an ebony frame with ivory scale, vernier and signature plate. The index arm and mirror supports are brass. Rather than use a sighting telescope, this… …
79hydrocarbon — hydrocarbonaceous, adj. /huy dreuh kahr beuhn, huy dreuh kahr /, n. any of a class of compounds containing only hydrogen and carbon, as an alkane, methane, CH4, an alkene, ethylene, C2H4, an alkyne, acetylene, C2H2, or an aromatic compound,… …
80magnetism — /mag ni tiz euhm/, n. 1. the properties of attraction possessed by magnets; the molecular properties common to magnets. 2. the agency producing magnetic phenomena. 3. the science dealing with magnetic phenomena. 4. strong attractive power or… …
