©Wellcome Library, London

Through his quantitative estimates of blood pressure, heart capacity and blood-current velocity, Hales made the first advances since William Harvey (1578-1657) in circulation physiology. In pursuit of his scientific investigations, Hales was a dauntless animal experimenter, a sideline which did not morally clash with his position as the parish priest of Teddington in Middlesex. Experiments on animals were culturally acceptable since many natural philosophers believed that they felt no pain. By the mid-18th century, however, influential writers like Samuel Johnson (1709-1784) were deploring the fact that animal experiments were being ‘published every day with ostentation' by doctors aiming to ‘extend the arts of torture'.

Line illustration by ‘Cuzzort'.

Source: Medical Times 1944, vol 72, page 315.