Page:Dictionary of National Biography volume 05.djvu/150

 Blackwall young. He had also one daughter, who married Mr. Pickering. The daughter of John Blackwall married William Cantrell, bookseller, Derby.  BLACKWALL, JOHN (1790–1881), zoologist, was born at Manchester 20 Jan. 1790. After some years' partnership with his father, an importer of Irish linen, he retired in 1833 to North Wales, settling ultimately at Llanrwst. As early as 1821 he published, in Thomson's 'Annals of Philosophy,' observations on diurnal mean temperature, and in 1822 some notes by him on migratory birds appeared in the 'Memoirs of the Manchester Philosophical Society.' This was followed by observations on the notes of birds. Fifteen of his first twenty-five papers were ornithological. Being attracted to the study of spiders and their webs, he was surprised to find scarcely any available authorities, and this determined his choice of a principal lifework. His first paper on spiders appeared in 1827 in the 'Transactions of the Linnean Society,'. on the means by which gossamer spiders effect their aerial excursions. In 1830 he published, in the 'Zoological Journal,' a paper on the manner in which the geometric spiders construct their nets. His papers were collected in 'Researches in Zoology,' 1834; the second edition, 1873, was not brought up to date. Blackwall pursued the study of the spiders of his own neighbourhood and their habits with extreme painstaking, almost wholly unaided by any British or foreign worker. His great work, 'A History of the Spiders of "Great Britain and Ireland,' 1861–4, published by the Ray Society, was unfortunately in the hands of the society ten years before its publication. It is full of minute detail, giving an almost photographic picture of the object. Nearly all his work was done without any aid but that of a pocket lens. Some of his type-specimens are lost, owing to their having been kept indiscriminately with others. His writing for the press was most remarkably clear, and scarcely a single correction was needed in his proof-sheets. He died 11 May 1881.  BLACKWELL, ALEXANDER (d. 1747), was an adventurer, whose career is for the most part enveloped in mystery and contradiction. It is admitted that he was born in Aberdeen early in the eighteenth century; Fryxell, the Swedish historian of the intrigue which brought him to the scaffold, says in 1709, but this seems too late. According to a contemporary memoir, his father was a petty shopkeeper; but this production, although professedly written at Stockholm, was to all appearance fabricated in London to serve a political object; and there seems no reasonable doubt that he was the brother of Dr. Thomas Blackwell [q. v.], and consequently the son of another Thomas Blackwell [q. v.] According to the anonymous biography referred to, he studied medicine at Leyden, under Boerhaave, and he may very probably have represented himself to have done so. As, however, we find him practising the trade of a printer in London about 1730, there is far more probability in the statement of an apparently well-informed correspondent of the 'Bath Journal,' ab- stracted in ' The Gentleman's Magazine ' for September 1747, that Blackwell, urged by ambition and restlessness, left the university of Aberdeen without taking a degree, and came up to seek his fortune in the metropolis. Having obtained employment from the printer Wilkins as corrector of the press, he married an excellent wife with a considerable portion, and set up as a printer on his own account. He seemed on the high road to prosperity, when he was ruined by a combination of the London printers, who opposed him as an interloper who had never been apprenticed to the trade. He spent two years in a debtor's prison, from which he was delivered by the enterprise of his wife [see ] He then took up the study of medicine and agriculture, and was frequently cor suited respecting the management of estates. Being introduced to the Duke of Chandos, he obtained employment as the director of that nobleman's improvements at Cannons, which situation he forfeited under circumstances not explained, but apparently little to his credit. 'It kept him,’ says the editor of the ' Gentleman's Magazine,’ annotating the article in the 'Bath Journal,’ 'from other employment.' The printer of the magazine was probably one of Blackwell's persecutors, yet this may have been the reason why, as stated in Chalmers's 'Dictionary,’ 'Mr. Blackwell's family were not very desirous of preserving his memory,’ and allowed the circulation of erroneous statements which have hitherto entirely misled his biographers. In 1741, 