The scroll at the end of the pegbox provides essential mass to tune the fundamental body resonance and provides a convenient grip for spare fingers to brace against when tuning one-handed (with the violin on the shoulder). Some "scrolls" are carved representations of animal or human heads instead of the classical spiral volute most normally seen. The maple neck alone is not strong enough to support the tension of the strings without distorting, relying for that strength on its lamination with the fingerboard. For this reason, if a fingerboard comes loose, as may happen, it is vital to loosen the strings immediately. The shape of the neck and fingerboard affect how easily the violin may be played. Fingerboards are dressed to a particular transverse curve and have a small lengthwise "scoop" or concavity, slightly more pronounced on the lower strings, especially when meant for gut or synthetic strings. The neck is not varnished, but is polished and perhaps lightly sealed to allow ease and rapidity of shifting between positions. Some old violins (and some made to appear old) have a grafted scroll or seam between the pegbox and neck. Many authentic old instruments have had their necks reset to a slightly increased angle and lengthened by about a centimeter. The neck graft allows the original scroll to be kept with a Baroque violin when bringing its neck to conformance with modern standard. Bridge The bridge is a precisely cut piece of maple, preferably with prominent medullary rays, showing a flecked figure. The bridge forms the lower anchor point of the vibrating length of the strings and transmits the vibration of the strings to the body of the instrument. Its top curve holds the strings at the proper height from the fingerboard, permitting each string to be played separately by the bow. The mass distribution and flex of the bridge, acting as a mechanical acoustic filter, have a prominent effect on the sound. Tuning the violin can cause the bridge to lean, usually toward the fingerboard, as the tightening of the strings pulls it. If left that way, it may warp. Experienced violinists know how to straighten and center a bridge. Sound post and bass bar The sound post or "soul post" fits precisely between the back and top, just to the tailward side of the treble bridge foot. It helps support the top under string pressure and has a variable