T.W. Graves, a general practitioner from Woburn, Massachusetts introduced a speculum of his own design in 1878 that incorporates features of a bi-valve and a Sims’ speculum in a base expanding instrument.  Devised at a time when this class of instrument was relatively expensive to manufacture, its inventor cleverly sought to supply a device adaptable to multiple uses. Accordingly, the bottom blade can be easily disengaged from the apparatus to function in the manner of a Sims Speculum.  The relatively longer posterior blade is on account of the greater depth of the posterior fornix.  Graves’ designed became the most popular form from the late 19th century and beyond.