478 



DALBY, ISAAC. 



\UNO, 



Grand-Duke of Frankfurt, with a condition that Eugene Baauharnoi*, 

 Napoleon's step-con, should be named hi* successor instead of Cardinal 

 Feech. Dalberg's grandeur however was very evanescent. In 1813 lie 

 wu forced to renounce all his secular acquisitions, and withdraw him- 

 self to bin spiritual duties as archbishop of Ratiabon, the only dignity 

 ho retained, and in that town he died on the 10th of February 1817. 



Throughout his career Dulberg maintained his character for active 

 benevolence. During his last residence at Ratiabon, notwithstanding 

 hi* age, he fulfilled the duties of his office in an efficient and con- 

 scientious manner, relieving the poor, assisting the industrious, encou- 

 raging the good, and reproving the bod, alike by his example and hu 

 discourse, in which be was never severe or impatient As a scholar 

 his reputation was very high, and there were few branches of art or 

 science of which be had not considerable knowledge. His writings 

 were chiefly on subjects of practical philosophy and [esthetics, which 

 a winning eloquence of style rendered very popular. The principal 

 are, ' Betrochtung u'ber das Universnm ' (' Contemplations of the 

 Universe'), 1777; 'Grundsusse der .'Esthetik' ('Principles of ..Es- 

 thetics'), 1791 ; 'Von dem Bcwusteeiu als allgemeinem Grande der 

 Woltweisheit ' (' Of the Memory us the General Foundation of Know- 

 ledge'), 179S ; ' Von dem Einflusae der Wissenschaften und Kunste in 

 Bexiehuug auf oSentliche Kuhe ' (' On the Influence of the Sciences 

 and Arts with reference to the Public Quiet '), 1793 ; and ' 1'erikle-t. 

 uber den Einfluas der schbnen Kunste auf das offcntliche Qliick' 

 ( Pericles, on the Influence of the Fine Arts on the Public Pros- 

 perity '), 1SOO. He also contributed many valuable papers to various 

 German periodical works. 



DALBY, ISAAC, one of the many self-taught men of this country, 

 who have attained considerable eminence in mathematical science by 

 the mere force of genius, and in defiance of the obstacles opposed by 

 fortune to their progress, was born in Gloucestershire, in the year 

 1744, and he appears to have been instructed in the rudiments of 

 Latin and arithmetic at a grammar-school in that county. By his 

 friends be was destined to be a clothworker, but his taste leading 

 him to the study of mathematics, he laboured, by the aid of Stone's 

 1 Euclid,' Simpson's 'Algebra,' and Martin's 'Trigonometry,' to qualify 

 himself to be an usher m a country school. In that capacity he was 

 employed for about three years, when he opened a school on his own 

 account in another put of the country, but meeting with no success, 

 be came up to London in 1772. Here he received the appointment of 

 uahor to teach arithmetic in Archbishop Tenison'i grammar-school 

 near Charing Cross, and while fulfilling the duties of that employ- 

 ment he became known to many of the most celebrated men of science 

 in town. Among these were Dr. Maskeline, the astronomer royal, 

 Dr. Mutton and Mr. Bonnycastle, both of the Uoyal Military Academy 

 at Woolwich, the Rev. Messrs. Crakelt and Lawson, and Mr. Landcn, 

 Mr. Wales, mathematical master of Christ's Hospital, and Mr. Witchel, 

 master of the Uoyal Naval Academy at Portimouth. Mr. Bayly, who 

 had been employed iu making astronomical observations in a building 

 erected near Uighgato by the Hon. Topham Beauclerk for philoso- 

 phical purposes, being engaged to sail with Captain Cook, Dalby, after 

 baring been about a year at the school above mentioned, was appointed 

 to succeed him. In this situation, besides his duties as observer and 

 librarian, he performed, under Dr. Fordyce, that of experimenter in 

 chemistry; and aiuid.t these employments he found time to make 

 himself acquainted with the French language and revive his know- 

 ledge of Latin. In 1781, Mr. Beauclerk's establishment baiug broken 

 up, and the library, instruments, &c., sold, Dalby was engaged to make 

 catalogue of the library of Lord Beauohamp ; and in the following 

 year be was appointed mathematical master of the Naval School at 

 Chelsea. This was supported by voluntary contributions, and it suc- 

 ceeded for a time under the management of Mr. Jonas Hanway ; but 

 the subscriptions falling oil; the institution was given up. 



In 17s7 Mr. Kamsden, the distinguished maker of philosophical 

 instruments, to whom for several years Dalby bad been known, 

 recommended him, as an assistant, to Major-Quneral Roy, who was 

 then employed in the trigonometrical observations for connecting the 

 meridians of Greenwich and Paris ; and during that and the following 

 year be was employed in extending the triangulation through Kent 

 and part of Sussex to the coast opposite France. Dalby wax subse- 

 quently employed in making the computations preparatory to the 

 publication of the account of the proceedings; and on this occasion 

 he was led to apply a theorem (ascribed to Albert Oirard) to the 

 purpose of computing the excras of the three angles of a spherical 

 trundle above two right angles. The account was published iu ( 

 Philosophical Transactions v for 1790; and in the volume for 1 

 same year is a paper by Dalby on the figure of the earth, iu which it 

 is proved that the 'excess' is, without sensible error, the same v. 

 the earth be a sphere or a spheroid. General Boy died in 17DO, and 

 i i tl..j following year Dalby wu engaged, together with Colonel 

 Williams and Captain (since Major General) Mudge, to carry on the 

 survey of England, The operations commenced by a rctncanuremcnt 

 of the original base on Hounslow lieath, and before Mr. Dalby quitted 

 that service the triangulation was extended through the southern 

 counties of England to the Laud's End. The accounts of the survey 

 were published in the Philosophical Transactions;' bvit in 17V-* 

 Dalby, together with Colonel Mudg-, made a revision of General Hoy's 

 papers, and connected the operations of that officer with those which 



had subsequently taken place to the end of 1796 : these form the 

 subjects of a volume which wai published separately. 



In the year 1709, on the formation of the Uoyal Military ' 

 at Ili.-h Wycombe, Dalby was appointed professor of inathrmn 

 the senior department of that institution. He continued to hold that 

 appointment during the years that tbe department to which he 

 belonged remained at High Wyeombe, and subsequently to its 

 removal to Farnbam in Surrey ; but in 1820, it b>-ing then uni; 

 the junior department at Sandhurst in Berkshire, his infirmities 

 obliged him to resign. He continued however to reside at Farnham 

 till his death, which took place October 14, 182*. when he wo* iu tbo 

 eighty-first year of bis age. 



HU attention to hi* duties was unremitting ; and besides his con- 

 tributions to the 'Ladies' Diary' and other works, he wrote for the 

 use of the Military College, a valuable ' Course of Mathematics,' iu 

 2 vols., which, with successive improvements, extended to a sixth 

 edition. 



(Leybourn, Mathematical Rtpotilory, voL v.) 

 J)'AU:MI;KHT. [ALBMBERT, D'.] 



DALGAUNO, GEORGE. The following short notice of this origin*! 

 but neglected author is in Anthony-a- Wood's ' Athena: Oxonienses,' 

 vol. ii., p. 506. " The reader may be -pleased to know, that one 

 George Dal^arno, a Scot, wrote n book entitled ' Ars Si.-noruni, 

 Character UniversalU et Lingua Philosophica,' London, 1661. This 

 book before it went to press the author communicated to Dr. Wilkin.-, 

 who, from thence taking a hint of greater matter, carried it on, ami 

 brought it up to that which you see extant. This Dalgarno was born 

 at Old Aberdeen, and bred in the university of New Aberdeen ; taught 

 a private grammar-school with good success for about thirty years 

 together in the parishes of St. Michael and St. Mary Magdalen in 

 Oxford ; wrote also ' Didaecalocophus, or the Deaf and Dumb Man's 

 Tutor ; ' and dying of a fever on the 28th of August 1687, aged sixty, 

 or more, was buried in the north body of the church of St. Mary 

 Magdalen." According to the above account, Dalgarno was born in 

 or before the year 1627, and he must have been residing at Oxford 

 in the year 1657 ; whether previous to that time, it does not a; 

 but it may not be erroneous to conclude that he went to Oxford to 

 avail himself of the advantages of that seat of learning. From the 

 works which Dalgarno left behind him, it may be concluded that ho 

 was a man of original talent, and of great acquirements ; his specu- 

 lations concerning a universal language, a favourite subject with the 

 learned men of his time, undoubtedly preceded those of Bishop 

 Wilkins, at that time dean of Ripon, and he received the testimony 

 of Dr. Setli Ward, the bishop of Salisbury, Dr. John Wallia, and 

 others, that he had discovered a secret "which by the leornc 1 

 of former ages had been reckoned among the desiderata of learning." 

 We have carefully sought for some acknowledgment of the merits of 

 Dilgarno in the ' Essay towards a Heal Character ' of ISUhop \\ 

 but his name is not once mentioned, though assistance from I >r. U urd 

 and others is noticed. Wilkius's work was published in 1668. Its 

 appearance had been delayed for two years in consequence of tlio 

 whole impression, when nearly printed, with the exception of two 

 copies, having been destroyed iu the great fire of London. Allowing 

 for this delay, Dalgorno's work had the priority by several years, and 

 Dr. Wilkins hod the advantage of seeing it " before it went to press." 

 This treatise, 'An Signorum,' Ac., exhibits a classification of ideas, 

 and a aeries of arbitrary signs or characters adapted to the classifica- 

 tion, so as to represent each idea by a specific character, without 

 reference to any language of words. All those persons who arc 

 ae.|u.iiutcd with the ' Essay ' of Wilkins will see the germ of it iu 

 this design of Dalgarno's. The ' Didascalocophua ' develops views 

 on tlie instruction of tbe deaf and dumb, both comprehensive and 

 practical. It is a truly philosophical guide, by which the wi !:> 

 how capable the deaf and dumb are of understanding and applying a 

 written language, and of their capacity to speak and to understand 

 the speech of other persons. He shows that the art of teaching this 

 class of persona requires the exercise of common souse, persevci 

 and ordinary patience, under a teacher, fertile in expedient*, and one 

 who is able to turn even disadvantages and difficulties to a good 

 account Dalgarno's stylo is quaint and pedantic, and rather ' 

 with long and technological words, which serve to exhibit the learning 

 of the author more than to increase the perspicuity of hi* work. 

 But this was the garb which learning too often assumed iu la 

 To Dalgarno is due the credit of inventing what H perhaps the iir-t 

 manual alphabet for the use of the deaf and dumb, and the one from 

 which the two-handed fiug-r alphabet now in use has probably been 

 derived. As few copies of his work are now to ba met with, we 

 shall give his hand-alphabet, and accompany it by as much of his own 

 explanation us seems necessary for understanding his views on dactyl- 

 ology. "After much search and many changes, I have at la-t lixt 

 upon a finger or hand alphabet according to my mind; for I think it 

 cannot be considerably mended, either by myself or any other (without 

 making tinker's work), for the purposes of which 1 have intended it ; 

 that iii, a distinct placing of and easy pointing to the single letters; 

 with the like distinct and easy abbreviation of double and triple 

 oouiouanU. 



" The scheme (I think) it so distinct and plain in itself, that it needs 

 not much explication, at least for the single Utter*, which are as 



