there are other abrasive materials whose
31Stone Age — the period in the history of humankind, preceding the Bronze Age and the Iron Age, and marked by the use of stone implements and weapons: subdivided into the Paleolithic, Mesolithic, and Neolithic periods. [1860 65] * * * First known period of… …
32human evolution — Evolution of modern human beings from nonhuman and extinct hominid forms. Genetic evidence points to an evolutionary divergence between the lineages of humans and the great apes (Pongidae) on the African continent 5–8 million years ago. The… …
33Harp — A medieval harp (left) and a single action pedal harp (right) String instrument Hornbostel–Sachs classification 322 5 (Composite chordophone sounded by the bare fingers) …
34Milling machine — For the machine used in road construction, see Asphalt milling machine. Not to be confused with mill (grinding). Example of a bridge type CNC vertical milling center …
35Europe — /yoor euhp, yerr / for 1; /yoo roh pee, yeuh / for 2, n. 1. a continent in the W part of the landmass lying between the Atlantic and Pacific oceans, separated from Asia by the Ural Mountains on the E and the Caucasus Mountains and the Black and… …
36Diamond — This article is about the mineral. For the gemstone, see Diamond (gemstone). For other uses, including the shape ◊, see Diamond (disambiguation) …
37seed and fruit — ▪ plant reproductive part Introduction respectively, the characteristic reproductive (reproductive system, plant) body of both angiosperms (flowering plants) and gymnosperms (conifers, cycads, and ginkgos) and the ovary that encloses it.… …
38Dice — For other uses, see Dice (disambiguation). Four coloured dice showing all six possible sides (on a right handed, 6 sided die with pips) A die (plural dice, from Old French dé, from Latin datum something which is given or played )[1] …
39Blacksmith — For other uses, see Blacksmith (disambiguation). Blacksmith A blacksmith at work Occupation …
40Psychological Operations (United States) — Infobox Military Unit unit name=United States Psychological Operations caption= dates= country=United States allegiance=Federal branch= type= role= |size=|command structure=Active Army U.S. Army Special Operations Command (USASOC) Reserve Army… …
