|MadSci Network: Science History|
You can ask the question "when where and who..." about inventions or discoveries. Often the story of inventions or discoveries is much more complicated than that. "When..." is usually the easiest, and usually gets a fairly definite answer. If the "when..." comes out at more than 2000 years ago, as it does with at least four of these five, the "where..." becomes difficult, and the "who..." impossible to answer. The answers given to "where..." in prehistoric cases are sometimes themselves questionable and culturally insensitive. Encyclopedias often come up with Europe-centred answers, assigning discoveries to Europe, the Middle East, North Africa, or West Asia, and showing little regard to other early societies in East Asia, sub-Saharan Africa, or Australia. The "who..." is inevitably long- forgotten. The earliest of these "machines" is probably the inclined plane. But what do you have to do to "invent" the inclined plane as a machine. Suppose you are with a stone age tribe, and you want to get something heavy to the top of a cliff. After a lot of fruitless struggling to lift it into place you say "Look, maybe it would be better to drag it around the slope. We'll have to go a bit further, but at least that way it will be a lot easier." Does saying something like that amount to "inventing" the inclined plane as a "machine"? Or do we require a bit more than that? It does not matter too much; however you add it up, the inclined plane was in use at the start of the stone age, and was an important feature of all of the megalithic cultures (pyramids, Stonehenge, Easter Island, etc.) The wedge is also an early stone age machine. The principle of the wedge has been in use for removing bark from trees in large single slabs for at least 4000 years in Australia, maybe much more, and probably as long or longer elsewhere. This is how early boats were made here. It is arguable that the wedge itself incorporates both the features of the inclined plane and the lever in its operation. Archimedes, Greece, 250 BC worked out a lot of the Maths of the lever. The principle of the lever as a tool was well known in ancient Greek culture, and almost certainly dated long before then. Using leverage to gain mechanical advantage would have been a necessary part of solving a lot of the mechanical problems facing stone age tribes. One place where a lever is used is in spear- throwing sticks. For the wheel, try this web page: wheel invention You will see on the page that it suggests over 5500 years ago in Iraq. With the pulley, things are not at all clear. The first question is whether a machine has to have an axled wheel to count as a pulley. Using a branch or sapling to change the direction of tension in a rope or cord is clearly a prehistoric strategy. This could have been refined with a worn groove in the sapling, and the worn groove could have been greased to make it slide better. From there it is a small step to a greased turnbuckle. At what stage did an axle and grooved wheel come in? Does a greased turnbuckle without an axled wheel count as a pulley?
Try the links in the MadSci Library for more information on Science History.