HCR diary 1.7.1821 "dined at Sieveking's met Dr Jenckel physician 2 New London St, Crutched Friars, translates English poems into German - a little dogmatical and a little mystical - I might say he is very much so"
                13.11.1821 "I called on Dr Jenckel 37 Gracechurch St. I sat a couple of hours with him - we talked about English poetry - he is an able man - his wife a respectable woman - but I fear they have not the means of continuing here"
                22.11.1821 "went to Sieveking - an agreeable chat with them - they want an introduction to Aders for themselves and Jenkin - they want to see the pictures and to introduce the Dr. to the house for more substantial service"
                15.12.1821 "at Aders where I waited to introduce to the Aders Dr & Mrs Jenkin and Mr & Mrs Sieveking. They came to see the pictures ostensibly but I think it will end, as I wish it may, in an acquaintance. Aders himself was pleased with Mrs S: and Mrs J: and showed in that his taste - but in general all the parties seemed to like each other"
                 29.12.1821 evening at Aders "the Masqueriers - Jenkins and a Mr & Mrs Dubusson were there"
                   12.2.1822 conversation with Mrs Aders "about her situation as to being visited by ladies. She is quite aware of the way in which she is looked upon by many, and feels about it just as she ought. She informed me that Dr & Mrs Jenkin are both divorced from former wife and husband and this the Sievekings know"
                   17.2.1822 "dined late at Sievekings. The Aders, Jenkins and Benickes there - a very agreeable evening"
                     5.4.1823 "went to Mrs Sieveking to enquire whether she knew anything of Dr Jenkin's mode of treating the cancer of which Mrs Aders had told me"
                   18.4.1823 "wrote to Mrs A: begging her to make enquiries of Dr Jenkin concerning his mode of treating cancer"
                    21.4.1823 "Mrs A: has called on Dr Jenkin and made enquiries about his mode of treating cancers - I obtained no very material information. He brings the cancer to a wound and then uses plaisters etc. He could tell in a fortnight whether he could cure the cancer or not - He never uses a knife but is in no case confident of success"
Marquardt II p 85 n 243 quotes Alten Geschichten, the memoirs of Henriette Benecke (1807-93 nee Souchay) who married William Benecke's oldest son Friedrich Wilhelm in 1826. My rough translation "Our very dear friend and doctor for many years was Dr Jenken, a German-Russian, whose lovable, truly charming wife, born a Countess von Löwenstein, on my first visit to England in 1823 made an unforgettable impression on me through her fine, perfectly refined and yet so heartfelt manner. She is still alive (1865) as a widow in London"
Amalie Löwenstein married Düsseldorf 13.6.1816 to Moyses Levy Horn. In a Mannheim family register readable on Ancestry (though the old German writing is hard to decipher) there is a record of Ferdinand Jenken Doktor Medicinae age 31 in 1819 born Reval, Nany Jenken age 24 born Würzburg, Julius Jenken age 9 born Reval, Josephine Jenken age 3 born Reval. Reval was the German name for modern Tallinn, Estonia. Jenken received his MD in 1815 at Dorpat (modern Tartu) the university town of Estonia. An Ancestry user-submitted tree states Ferdinand Jencken was born Estonia 21.12.1785. On 20.6.1839 Josephine Elizabeth daughter of Ferdinand Johann Jenken and Anna Josephina Renate Müller was married to Friedrich Goerlitz. So Dr Jencken's divorce and Amalie Horn's divorce and their marriage must have happened around 1820. Ferdinand Edward born 12.9.1822 bapt 10.10.1822 Whitechapel, Heinrich Diedrich born 5.9.1823 bapt 17.10.1823 Whitechapel both of Ferdinand & Amalia Jencken.  Henry Diedrich Jencken (34) late of Cape of Good Hope, son of Ferdinand John Jencken M D of Frankfurt admitted Lincolns Inn 4.6.1858, called to the bar 30.4.1861.  Morning Post 25.3.1865 on 22.3.1865 at 11, Royal Terrace, Kingstown, Dr F J Jencken died in his 79th year.  Liverpool Mercury 15.2.1878, on 11.2.1878 at her residence, Kingstown at the close of her 95th year, died Amalie Jencken nee de Loewenstern relict of Ferdinand Jencken M D late of London (Kingstown is near Dublin, Ireland).  H D Jencken was active in the 1860s and 1870s in the Royal Institution, the Freed-Mens Aid Society (devoted to the interests of the freed coloured people), the National Association for the Promotion of Social Science, the International  Law Reform Society, he discussed Buddhism with Prof Tagore at the Ethnological Society, was set on by a mob in Spain being thought a child-stealer, and was an enthusiastic spiritualist who claimed to have witnessed strange phenomena produced by the medium Daniel Douglas Home (DNB 1833-1886). In 1869 he published, with much of his own commentary, his father's Treatises on Light, Colour, Electricity and Magnetism (online at and in the preface listed his father's works, which as well as many treatises on philosophy &c, included a translation of Herder's Cid into English and one of Shakespeare's Hamlet into German. I haven't read the philosophy, which would perhaps today be called pseudoscience and/or perhaps belongs in the tradtion of Goethe's Theory of Colours. H D Jencken also mentioned that his father had been blind for the last 30 years of his life and his manuscripts were written by a Mrs Mary Hennings, by 1869 in her 80th year. According to Boase, Modern English Biography, H D Jencken's older brother Ferdinand Edward was born blind and had sight in one eye restored when he was 17 by removal of a cataract by a Dr Franz. In 1838 (so while still blind) he published a composition Goethe's Ode to the Moon for pianoforte and guitar, he was a merchant in London in 1847, married on 7.10.1848 at Guernsey Eliza Druce, was of Sydney Australia in 1852 in the gold business. He became a doctor - either he or his father was admitted MRCP in 1853 as Dr Jencken of the Cape (Daily News 29.6.1853) and his son Francis John Jencken became an army surgeon dying childless in 1943 (Who Was Who). Dr F E Jencken appeared in a list of persons expected to feature in the Dictionary of National Biography (Athenaeum 5.10.1889 p 455) but the name Jencken does not feature in a full text search of the DNB today. Boase also stated that Dr Jencken senior first came to England as doctor to Queen Adelaide (DNB 1792-1849), who would then have been Duchess of Clarence, but this is hard to square with the Jencken's apparent poverty (see above 13.11.1821). On 14.12.1872 H D Jencken married at St Marylebone Katherine Fox, one of the sisters who had set off the spiritualist craze in America, and they had two children (American National Biography 1836? -  2 July 1892). Both the Jencken brothers died in 1881, Dr Ferdinand by blood poisoning contracted while treating a poor patient in Kingstown. H D Jencken and his wife and two children were recorded in the 1881 census in London, but I could find none of the family in the 1841 to 1871 England censuses. According to Hasselblatt's Album Academicum of the University of Dorpat (1889) Ferdinand Jencken was born (?) 10.10.1786 in Estonia, studied medicine at Dorpat 1804-1806, continued his studies in Göttingen, Würzburg and Berlin, became MD 1815, was town doctor in Reval, went to Germany 1819, London in 1820, St Petersburg in 1829, was in Coburg from 1830 to 1851 where he established an orthopaedic institution in Schloss Altenstein, from 1851 in London again, was doctor in Bonn, Eisenach and from 1854 in Mainz, lived on the Island of Jersey and then moved to Kingston, Ireland where he died in 1864. (Presumably) his son Julius was born in Estonia 8.8.1810, studied medicine at Dorpat 1830 to 1836, held various official medical positions including in St Petersburg and was physician to the Duke von Oldenburg, died 21.9.1870 St Petersburg


This on demand or ebook published in 2016 contains much more information on the Jencken family: 
Victoria Joan Moessner's  Book: "Amalie Christine Jencken 1785 to 1878 – From Estonia to Ireland to Australia and Inbetween"
Hope this proves useful. Best....Malcolm