the hair dryer was invented by Alexandre in 1890 but the first had held hair dryer was invented 1971.
Many people believe that the seven day week, an almost universal concept across all cultures, originated because of the movements of seven heavenly bodies, that is the Sun, Moon, Mercury, Mars, Venus, Jupiter and Saturn, all of which are visible with the naked eye, and which move around the sky seemingly at random (in the case of the planets). All of these were important to the ancients, and each then represented a day: Monday - Day of the Moon Tuesday - Day of Tiw (the Norse equivalent of Mars, the war god) Wednesday - Day of Woden/Odin (the Norse equivalent of Jupiter, the chief god, but here equating Mercury) Thursday - Day of Thor (Again, Jupiter, the god who makes thunder) Friday - Day of Freyja (the Norse equivalent of Venus, the goddess of love) Saturday - Day of Saturn Sunday - Day of the Sun Here then is the week, which is also conveniently a quarter of the lunar cycle, or month. This was a very useful unit of timekeeping, as it allowed farmers to plan the times of planting their crops more accurately than just using the moon.
Slavery in general started thousands of years ago, when one group of people captured members of another group of people. The beginnings aren't certain, but it was going on in ancient Egypt, Rome, Greece, Japan, Ancient America... you name it. Slavery in Africa also started thousands of years ago. When one tribe would battle with another, the "loosers" were often captured and forced to work or to be second class "wives" to tribsmen. When the Dutch traders visited Africa seeking something of value to trade, many of the tribes offered captured enemies as a comodity in exchange for the trinkets and other goods offered by the Dutch traders. For many of the slaves, the conditions were better than they would have encountered had they remained the "property" of their enemies in Africa since many of them would have been murdered for their "crime" of being a member of the enemy tribe. That is not to say that there was anything good about slavery. It was a truly evil practice, where one group of people considered themselves to be sufficiently superior to another that they felt the right to "own" a fellow human being. It is generally agreed that the world has become a little more enlightened in the not too distant past, and we have learned to treat even our enemies with enough respect that they are no longer considered slaves.
You can find out allot about this by watching the movie Killing Fields...
-i was looking up the same thing!