John Stevens Henslow (1796-1861) was a distinguished geologist, mineralogist and botanist and a remarkable teacher, who revived and popularized the almost defunct subject of Botany at the University of Cambridge in the early 19th century. He was appointed Professor of Mineralogy in 1822 and to the Chair of Botany two years later at the age of just 29. He made two highly significant contributions in Cambridge. He is remembered with much affection for creating the ‘new’ University Botanic Garden on Trumpington Road, which from its foundation has not only been a centre of scientific research but also one of the most popular public amenities in the City. With Adam Sedgwick (1785-1873), Woodwardian Professor of Geology, he founded the Cambridge Philosophical Society in 1819. He is also recognized as the mentor of the young Charles Darwin, to whom he gave his own ideas concerning populations, variation and the nature of species. He recommended Darwin to Captain Fitzroy for the voyage of HMS Beagle as someone “worthy of recording everything worthy of note in natural history”.
John Henslow graduated from St John’s College and, in the same year he received his first Chair, he was ordained into the Anglican Church. Thus, from 1823 onwards, he combined his clerical duties with his academic work. He was appointed as Rector of Hitcham, Suffolk, in 1837 and moved there in 1839. He continued to hold his Chair of Botany at Cambridge and give his Easter term botanical course until his death in 1861.
The original Botanic Garden in Cambridge was a four acre plot of land in the centre of the City between Pembroke Street and Bene’t Street, now known as the New Museums Site. This was a physic garden for the training of medical students. When Henslow became Professor of Botany he persuaded the University to acquire a much larger site of 40 acres on the outskirts of the City where he created the new Botanic Garden. This garden was the first ever designed for the scientific study of the plants themselves, rather than to illustrate their uses in medicine or economics. He planted a superb collection of trees, interspersed with shrubs and herbs, arranged according to the most up-to-date taxonomic arrangement – the natural system of Augustin de Candolle. The Systematic Beds in the Garden are unique in displaying this systematization of knowledge as a ‘living book’. In 2006 a Blue Plaque was unveiled in the Garden to commemorate Henslow as its founder
In 1819 Henslow went on a geological tour of the Isle of Wight with his friend, Professor Sedgwick. During this walk they conceived a project to institute a society in Cambridge ‘as a point of concourse for scientific communication’. After their return the Cambridge Philosophical Society was instituted for the purpose of ‘promoting Scientific inquiries and of facilitating the communication of facts connected with the advancement of Philosophy’. Rev. W Farish, Jacksonian Professor was elected first President of the Society. Sedgwick was its first Secretary but from 1821 to 1839 Henslow himself held this position. The Society was granted a Royal Charter in the Reign of King William IV and has continued to pursue Henslow’s vision for almost 200 years.
In 2009, the Cambridge Philosophical Society established the Henslow Research Fellowships in honour of the Society’s founder, John Stevens Henslow. The Society selects colleges who award fellowships to promising young scientists to enable them to carry out independent research for a period of up to three years. The first two Henslow Fellowships were awarded by Downing College and Robinson College.