Combination saw and forceps used in trephination

Combination saw and forceps, brass and steel, with ebony handles, made by Thomas Machell, c. 1815

Thomas Machell hoped that this invention, which he called the ‘annular saw’, would combine all the instruments required for trephination into one single device. The skull is sliced by the circular saw blade, which could cut to a range of depths and is operated by the handle. The forceps are operated by the screw. Unfortunately for Machell, it was found that separate tools could be used to perform the operation more efficiently and so his instrument never enjoyed widespread use. Thomas Machell’s account of his saw can be found in 'The Edinburgh Medical and Surgical Journal', July 1815.