John Stevens Henslow

John Stevens Henslow (February 6, 1796 - May 16, 1861) was an English botanist and geologist.

Henslow was born at Rochester, the son of a solicitor John Prentis Henslow, who was the son of Sir John Henslow. He was educated at St. John's College, Cambridge where he graduated as 16th wrangler in 1818, the year in which Adam Sedgwick became Woodwardian Professor of Geology. He married Harriet Jenyns (1797–1857), daughter of George Leonard Jenyns and sister of Leonard Jenyns in 1823. Their daughter Frances Harriet married Joseph Dalton Hooker.

Early career

Having graduated in 1818, Henslow was soon appointed a Fellow of St John's College, Cambridge. He developed a passion for natural history which largely influenced his career, and he accompanied Sedgwick in 1819 on a tour in the Isle of Wight where he learned his first lessons in geology. He also studied chemistry under Professor James Cumming and mineralogy under Edward Daniel Clarke. In the autumn of 1819 he made valuable observations on the geology of the Isle of Man (Trans. Geol. Soc., 1821) and in 1821 he investigated the geology of parts of Anglesey, the results being printed in the first volume of the Transactions of the Cambridge Philosophical Society (1821), the foundation of which society was originated by Sedgwick and Henslow.

Meanwhile, Henslow had studied mineralogy with considerable zeal, so that on the death of Clarke he was in 1822 appointed Professor of Mineralogy in the University of Cambridge. Two years later he took holy orders. Botany, however, had claimed much of his attention, and to this science he became more and more attached, so that he gladly resigned the Chair of Mineralogy in 1825, to become Regius Professor of Botany. As a teacher both in the classroom and in the field he was eminently successful. He was a correspondent of John James Audubon who in 1829 named Henslow's Sparrow after him, and to Henslow, Darwin largely owed his attachment to natural history, and also his introduction to Captain Fitzroy of HMS "Beagle". Henslow founded the Cambridge University Botanic Garden in 1831.

A country clergyman

In 1832 Henslow was appointed vicar of Cholsey-cum-Moulsford in Berkshire (now Oxfordshire). He continued to live in Cambridge, only visiting the parish during vacations; no doubt he appointed a Curate to conduct services and parish business during term-time.

However, his appointment in 1837 to the remunerative Crown living at Hitcham, Suffolk marked a turning-point in his life. This time, in 1839, he moved to the parish, and as Rector of Hitcham he lived at the Old Vicarage. He worked there, endearing himself to all who knew him, until the end of his life. His energies were devoted to the improvement of his parishioners, but his influence was felt far and wide. Botany at Cambridge suffered, attendance at lectures fell, and we have records of complaints made within the university. ["Memorials, Journal and Correspondence of Charles Cardale Babbington" 1897. p297] Henslow did not resign his Chair, and continued to give lectures, set and mark exams, and take part in university affairs. Nevertheless, his influence there was naturally much reduced.

Henslow's work in Hitcham, over and above the normal duties of a Rector, can be summarised as follows: [Russell-Gebbett J. 1977. "Henslow of Hitcham: botanist, educationalist & clergyman". Dalton, Lavenham. ] :1. "The Parish School and other charities". Hitcham was a poor parish, and most people would have been illiterate. Education had to be paid for, and so Henslow both raised funds and donated his own money to support a school. The school was founded in 1841, and Henslow himself gave a series of volunteer classes on Monday afternoons for some of the older children. Botany and general scientific thinking were part of the fare. The botanical curriculum was printed: it was rather heavy with morphology and technical terms.
The botany taught in this school had effects throughout Britain, because important people at the centre, such as Prince Albert and Lyon Playfair kept in touch and rightly regarded Henslow as an authority on the subject. :2. "Adult education in the Village". The Hitcham Labourers' and Mechanics' Horticultural Society was the vehicle used by Henslow to 'improve' the labouring and agricultural workers in the village and its surounds. Competitions, shows and excursions were the attractions, and the intent was practical, to improve agriculture by improving the parishioners. Again Henslow made use of gifts and facilities provided by his friends.:3. "Tackling the farmers". Surprising to us now, in those days the farmers were something of an obstacle to progress. The had not yet caught on to the advances made by Justus von Liebig in Germany, who began to apply chemistry to the needs of agriculture. Despite this, Henslow pressed on with ideas about field experiments which would try out various fertilisers and measure resultling product. Questions such as "Should gypsum be added to manure heaps to fix the ammonia?" were proposed, no doubt to much muttering "sotto voce", and head-shaking from the farmers. It is only fair to add that Henslow did eventually get a good deal of help and acceptance for his ideas.:4. "Museums". The big town of Ipswich is twelve miles from Hitcham. As a result of his Cambridge experiences, Henslow believed in the value of museums as vehicles for education. The museum at Ipswich, which was established in 1847, owed much to Henslow, who was elected President in 1850. The museum was based on natural history, construed in the broadest sense. A conflict between the Curator, a Dr Clarke, and the "vile and disorderly mob that contaminates our room on public nights" with their "obscene conversations [and] indelicate and blasphemous retorts" reminds us that delivering education to the people can be a challenging undertaking!

Alongside this work he remained an inquiring scientist at heart. In 1843 he discovered nodules of coprolitic origin in the Red Crag at Felixstowe in Suffolk, and two years later he called attention to those also in the Cambridge Greensand and remarked that they might be of use in agriculture. Although Henslow derived no benefit, these discoveries led to the establishment of the phosphate industry in Suffolk and Cambridgeshire; and the works proved lucrative until the introduction of foreign phosphates.

Henslow died at Hitcham. His publications included "A Catalogue of British Plants" (1829; 2nd ed 1835); "Principles of Descriptive and Physiological Botany" (1835); "Flora of Suffolk" (with E. Skepper) (1866).

References

Further reading

* Nora Barlow {ed). 1967. "Darwin and Henslow: The Growth of an Idea. Letters, 1831–1860". Murray, London.
* L. Jenyns, "Memoir of the Revd John Stevens Henslow" (London 1862)
* S. J. Plunkett, Ipswich Museum Moralities in the 1840s and 1850s, in C. Harper-Bill et al. (ed) "East Anglia's History: studies in honour of Norman Scarfe" (Boydell, Woodbridge 2002), 309-332. ISBN 0-85115-878-1
* Jean Russell-Gebbett, "Henslow of Hicham, botanist, educationalist and clergyman" (Lavenham 1977).
* S. M. Walters and E. A. Stow, "Darwin's Mentor" (Cambridge University Press 2001). ISBN 0-521-59146-5
* Image source: "Portraits of the Honorary Members of the Ipswich Museum" (Portfolio of 60 lithographs by T.H. Maguire) (George Ransome, Ipswich, 1846-1852)

External links

* [http://www.ely.anglican.org/about/good_and_great/henslow.html Biography of John Stevens Henslow, Diocese of Ely]

The standard botanical author abbreviation Hensl. is applied to plants described by this botanist.