2008年11月30日星期日

Sickle


sickle is a hand-held agricultural tool with a curved blade typically used for harvesting grain crop or cutting grass for hay. The inside of the curve is sharp, so that the user can draw or swing the blade against the base of the crop, catching it in the curve and slicing it at the same time. The material to be cut may be held in a bunch in the other hand (for example when reaping), held in place by a wooden stick, or left free. When held in a bunch, the sickle action is towards the user (left to right for a right-handed user), but when used free the sickle is usually swung the opposite way. Different types may be referred to as a grasshook, swap hook, rip-hook, slash-hook, reaping hook, brishing hook or bagging hook.

Using a sickle
The blade of a sickle is often cranked to one side, to make it easier to keep the blade closer to the ground; this makes it right- or (more rarely) left-handed. Sickles used for reaping are usually serrated.
The sickle was largely superseded by the scythe, which is more comfortable and efficient to use for many purposes, but it continues in use in many parts of the world, and for certain uses where a scythe is not convenient. The most noticeable difference between a sickle and a scythe is the length of the handle – a sickle is a one-handed tool with a short handle, used while bending down to the ground, while a scythe is a two-handed tool, used standing up, with a long, often curved haft, and a much longer blade.
A blade which is used regularly to cut the silica-rich stems of cereal crops acquires a characteristic sickle-gloss, or wear pattern. When this pattern appears on ancient stone tools, it can indicate early use or development of agricultural use.
In Greek myths, the sickle was used as a weapon by Cronus and Perseus.

Additional uses
The sickle is used as part of the well known symbol of the hammer and sickle, which is the symbol of Communism or Revolutionary Socialism. The sickle represents the agricultural working class or peasantry in this symbol.
Sickle is a fictional unit of money in the Harry Potter series.
SS-25 Sickle is the NATO reporting name for the RT-2PM Topol intercontinental ballistic missile.
Tacitus reports that golden sickles were used in Druidic rituals.

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