This is a device for measuring the size of human heads (and
hence brains), developed by Sir Francis Galton (1822–1911). Known
as the ‘father of eugenics’, Galton was influenced by the
evolutionary theories of his cousin Charles Darwin and
believed in the need to improve human races via selective breeding.
Using a variety of ‘anthropometric’ devices to measure the
proportions of the human frame, he sought evidence of links between
physical appearance and the supposed evolutionary progress of
different population groups.