Number of words – 132 An intriguing combination of Harvey’s idea of the heart as a pump with the idea of air pressure was made in early 1700 by Stephen Hales. This English clergyman used a barometer arrangement to make a direct measurement of the blood pressure of a horse. He inserted at tube into a … Read more

Number of words – 369 Thomas Newcomen was an iron monger and blacksmith in Devonshire. With a local plumber, John Kelly, Newcomen experimented on a different kind of engine during the first decade of the 18th century. The first successful installation was in Staffordshire in 1712. By 1720, the engine was being widely used, and continuously … Read more

Number of words – 309 The alchemist called some shiny minerals by the name vitriol, from the Lateen word for glass. There were blue vitriol and green vitriol. In smelting minerals to obtain metals, artisans got copper out of blue vitriol and iron out of green vitriol. Later, alchemists found that if they strongly heated … Read more

Number of words – 116 Another stone alignment was the west coast of Scotland is simpler, probably older, and in a way, more striking than Stonehenge. If you stand on a little stone platform and look toward the southwest over the top of a vertical stone, you can see a notch formed by two mountains … Read more

Number of words – 328 To make any longer voyages, the Portuguese needed better ships. And in Lisbon, they created a revolutionary new types of ship. The Portuguese built ships that combined two earlier traditions of the North Sea and the Mediterranean. Traditions which differed because of the conditions of the seas they sailed. The … Read more

Number of words – 293 The metric unit of energy is the joule. It’s named after James Joule, with the symbol J. Although the names of all units are written in lower case letters, their symbols are capitalized when they’re derived from the name of a person: so the newton of force is symbolized N. … Read more

Number of words – 262 Why were these particular pyramids built? Were they just individual tombs for individual pharaohs? Here’s where there’s some disagreement. Traditional Egyptologists suppose that a new pyramid was built for each new pharaoh. But if a pharaoh reigned 40 years, and his pyramid could be completed in 20, the huge work … Read more

Number of words – 344 Imagine how surprised the first Neolithic farmer must have been when he hit a pebble with his stone hammer and instead of shattering, the pebble just bent. A nugget of native copper! Copper does sometimes occur pure, in small nuggets. By banging away at it our Neolithic hero could form … Read more

Number of words – 297 In more temperate regions in Africa, there are hunter-gatherer tribes today who manage well enough by spending only a couple of days a week in food gathering task. They may not have their own kinds of leisure time activities. So, if the Neolithic life style was that pleasant, why did … Read more

Number of words – 244 Occasionally, when an adult sheep has been killed by humans for food, a lamb remains that’s taken back to the camp for a pet. The lamb is fed and becomes somewhat tame. Others, over the generations receive the same treatment, and with the right genetic variations may lose some of … Read more