In 1862, Pettigrew accepted the post of Assistant Curator at the
Hunterian Museum of the Royal College of Surgeons in London. Here he contributed some 600 dissections, mostly of cardiac muscle, the urinary bladder and the prostate. He held the position for five years. During this time he started to collect evidence that led to his pioneering theories of flight. In 1867 he gave lectures to the
Linnean Society on the nature of the mechanical appliances necessary to make flight possible. He showed that the figure-of-8 movements of wings in the animal kingdom were identical to those made by wings in flight. In 1867 he became unwell suffering from 'a condition of the retina'. He took a break in Ireland to continue to study the flight of birds and bats. In 1870 he published his
theory of flight in which he demonstrated that: insects, bats, and birds fly by figure-of-eight movements; that the wing of the insect, bat and bird, are screws structurally like the blade of a screw propeller; that wings have a reciprocating action and that wings describe a figure-of-eight track. He had a passionate interest in animal locomotion and, more particularly, in the theory of flight, and around the turn of the century made several prototypes of an
ornithopter of his own design. In 1868, at the age of 36, Pettigrew was elected a
Fellow of the Royal Society. In 1869 he returned to Scotland to take up an honorary position as Curator of the museum of the
Royal College of Surgeons of Edinburgh and employment as pathologist to the
Edinburgh Royal Infirmary. In 1872 Pettigrew was elected a member of the
Harveian Society of Edinburgh and served as president in 1889. In 1873 he was elected a Fellow of the
Royal Society of Edinburgh his proposer being Sir
Thomas Richard Fraser and later that year was elected a Fellow of the
Royal College of Physicians of Edinburgh. In March 1873 he became a lecturer in Physiology at the
Edinburgh Extramural School of Medicine. In 1873, Pettigrew published
Animal Locomotion: or Walking, Swimming and Flying, his most popular work. In 1875, he was appointed to the Chandos Chair of Medicine and Anatomy at
St Andrews University and established a home on
The Scores which he called
Swallowgate because of its situation which allowed him to observe birds in flight. Over several subsequent years, Pettigrew assembled his
magnum opus Design in Nature, published in three volumes and lavishly illustrated with engravings and photographs. Its publication was completed in 1908. In this work, he showed some indifference to
Darwinism and mainstream
evolutionary biology, favouring
teleological points of view instead. His reputation was subsequently overshadowed by that of his colleague
D'Arcy Wentworth Thompson. Pettigrew lived at 4 Randolph Place in Edinburgh's West End. He died at his home in St Andrews in 1908. Pettigrew's grave is in the Eastern Cemetery of St Andrews, linked to the southern wall of the grounds of
St Andrews Cathedral. His widow and her second husband, Professor
James Musgrove, were later buried beside him. ==Family==