Excerpt:
Timeline: Beginning with the Age of Discovery, this resource lists events chronologically and provides an excellent overview and context for events occuring in the nuclear age.
Timeline: Beginning with the Age of Discovery, this resource lists events chronologically and provides an excellent overview and context for events occuring in the nuclear age.
Paint -- the group of emulsions generally consisting of pigments suspended in a liquid medium for use as decorative or protective coatings -- made its earliest appearance about 30,000 years ago. Cave dwellers used crude paints to leave behind the graphic representations of their lives that even today decorate the walls of their ancient rock dwellings.
Salt is physiologically absolutely necessary for human life, but in the past prior to the Industrial Revolution the known mineral salt sources were limited so much so, that its supply was a critical demographic power factor for most communities, until industrial means of extraction from brines were devised. It was only available as visible and exposed rock outcrops in arid regions, or as dried out salt cake on the shores of some seas and salt lakes. In areas with wet climates, the protruding salt dissolved making it almost impossible to discover. It is probably this, more than for any other reason, that many of the great civilisations first developed near deserts and desert climates, for example the Mediterranean region, at the edges of the "arid" zones.
A submarine is a vessel which has been designed for underwater operations. It has the capability to operate underneath the surface or on the surface of the water. This along with it's armament makes it a vital piece to our nations sea power and sea control.
Evidence of this type of craft goes back into history an estimated 2000 years. Aristotle has described for us a type of submersible chamber that was used in the year 332 B.C. These were used by the sailors of Alexander The Great during the blockade of Tiros in order to put obstacles and some types of charges of unknown kind.
From ancient times through the Middle Ages, and into the 13th century, man or animal power was the driving force behind hoisting devices.
By 1850 steam and hydraulic elevators had been introduced, but it was in 1852 that the landmark event in elevator history occurred: the invention of the world's first safety elevator by Elisha Graves Otis.
The first passenger elevator was installed by Otis in New York in 1857. After Otis' death in 1861, his sons, Charles and Norton, built on his heritage, creating Otis Brothers & Co. in 1867.
According to the Corning Museum of Glass web site, glass making was discovered by potters in Mesopotamia, within the area now known as the countries of Iraq and Syria."As early as 3,300 years ago, secret "instructions" for furnace building and glassmaking in Mesopotamia were written on clay tablets in a cuneiform alphabet. These instructions were copied and recopied over the centuries." (From the Corning Museum site.) A glimpse of glass making in the 4th Century A.D. is provided by a huge glass slab found in Beth Shearim, Israel. See below for more information about the Corning Museum web site.
The engraving is not a drawing transferred onto wood, metal or stone; it is conceived in consideration of the material which is used to make it, its nature, resources and potentialities; this is the essential starting point for achieving a style. Because it is on the matrix and not on the paper that the artist puts his creative stamp, which will be revealed in the finished print
Dot-dash radio telegraphy (primarily Marconi) was used experimentally
as early as 1897. By 1910, in general use for ship-to-shore communication.
This was not "broadcasting" but point-to-point communication. What
made broadcasting possible was the invention of the audion tube by
DeForest in 1906-the tube permitting modulation of sound.
The main function of all castles was defense, everything else was secondary. They were always surrounded by a curtain wall, which was often supplemented by a reinforced shield wall at strategic points. Crenellated battlements and arrow slits protected the defenders, and attackers often also had to overcome a series of several gates. The main entrance was protected by a drawbridge and machicolations projecting over the gate, from which boiling liquids and missiles could be dropped on the hapless foes below. The final refuge of the castle residents was the stronghold, or keep. It was the tallest and strongest building within the walls, with a high entrance accessible only via a removable ladder or wooden bridge. In addition to being a watchtower and the centre point of the entire castle, the keep was also a status symbol. The main residential building (great hall) was called the Palas. The castle chapel was often installed in the gatehouse or one of the main towers (nearer my God to Thee!), and a small garden inside the walls provided herbs, flowers and vegetables in emergencies. Offices and service rooms were generally located in the outer ward.