Bow frog

The bow frog is the end part of a stringed musical instrument's bow that encloses the mechanism responsible for tightening and holding the bow hair ribbon. Most of the bow frogs used in today's classical bows are made of ebony; some synthetic bows have frogs made with materials that imitate ebony, while Baroque bows use frogs made with various woods.

The origin of the name frog is unknown, although it may derive from the use of the frock, the small device that bow makers use to shape it. It is also referred to as the "heel" or "nut" of the bow. The German equivalent Frosch is the literal equivalent of "frog," while in French and Italian the equivalent of "heel" is used (talon and tallone). French also uses hausse. The foreign language terms sometimes appear in musical instructions, such as au talon, indicating to play with the bow near the frog. However, the English term is also used, such as in the Alfred edition of George Gershwin's An American in Paris, in which the violins and violas are instructed to play "near the frog" at bar 32.

During the earliest periods of music history, prior the Baroque era, the frog was a curved piece of wood affixed to the bow that served as a sort of rail to guide the hair ribbon and separate it from the stick. The bow hair was attached at both ends of the stick to the head and handle. The musician had to stretch and release the hair ribbon while playing in order to obtain the desire tension.

The first attempt to mechanically adjust the hair tension came with the “crémaillère”, a notch and hook system that pulled the hair ribbon by cranking the frog back and released it while moving forward. This uneasy device added considerable weight to the bow and was seldom used, but the concept for a new mechanical function of the frog was progressing.

With Baroque bows the frog was made with either the same wood as the stick or ivory. The woods typically used were common exotic woods, such as snakewood or amourette. During this time bow makers began carving the ivory, shifting their focus to the frog's aesthetic beauty.

A major improvement came with the screw and eyelet system, beginning in the 18th century. This was used in the workshop of Antonio Stradivari, and became the standard with the Transition bow, exemplified by the Cramer bow.

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