

TROUGHtfON TYPE-FOUNDING. 



Portsmouth, and in the next year physician to the 

 iWf . 11 1- tore this period, the medical discipline of 

 tin- navy had been in a miserable state, both as re- 

 spi-ctcd the can- of the men's health, and the ad- 

 vancement of the medical officers. Dr Trotter, 

 however, presently arranged these matters in a sys- 

 tematic manner ; and the many marks of respect 

 which were shown him, both by officers and by 

 M. mi, MI, an- the best proofs of the advantageous 

 nature of the changes which he effected.* On his 

 retirement from the navy, Dr Trotter settled at 

 Newcastle, where he practised for many years with 

 great reputation, occasionally amusing himself with 

 poetry and other elegant literary pursuits. He died 

 on the 5th Sept. 1832. His professional works 

 deservedly rank high, and their authority is fre- 

 quently quoted by medical professors and teachers. 

 The titles of his publications not already men- 

 tioned, are, in chronological order, as follows: 

 Medical and Chemical Essays, 1796. Medica Nau- 

 tica, or an Essay on the Diseases of Seamen, 1799, 

 3 vols. 8vo. Suspiria Oceania, a Monody on the 

 Lite Karl Howe. An English edition of his Essay 

 on Drunkenness, 1804. 4th edition 1812. An Ad- 

 dress to the Proprietors and Managers of Coal 

 .Mines, on the Means of destroying Damp, 1806. 

 A View of the Nervous Temperament, being a 

 practical Treatise on Nervous, Bilious, Stomach, 

 and Liver Complaints, 1812, 8vo. The Noble 

 Foundling, a Tragedy, 1813. A volume of Poems ; 

 also many communications to the Medical Journal, 

 the European Magazine and other periodical works. 

 TROUGHTON, EDWARD, an eminent mathe- 

 matical and astronomical instrument maker, was a 

 native of Cumberland. At the age of seventeen 

 he came to London, and was instructed by an elder 

 brother in the rudiments of the art in which he 

 afterwards so greatly excelled. About the year 

 1780, in conjunction with his brother, he settled 

 in Fleet street, and at that early period of his life 

 laid the foundation of his future fame. His inven- 

 tion of a method by which the graduation of in- 

 struments of the largest class could be effected 

 with a degree of ease and accuracy unattainable by 

 any former means, and the construction of an en- 

 gine (still in the establishment of his successor) 

 for the division of those of smaller dimensions, 

 added to the skill and care employed in their ar- 

 rangement arid execution, gave to his works a su- 

 periority that was early appreciated by those whose 

 pursuits required such assistance. His method of 

 original graduation was disclosed to the public 

 through the medium of the royal society, in the 

 year 1809 ; and the Copley medal was awarded to 

 him by that learned body, of which he was shortly 

 afterwards elected a fellow. Of the astronomical 

 society he was an original member, subsequently 

 one of the vice-presidents ; and to the close of his 

 life felt a lively interest in its prosperity. His celeb- 

 rity was not confined to his native country, for 

 about the year 1830 the gold medal of science was 

 presented to him by its illustrious patron the king 

 of Denmark. To what extent the present state 

 of navigation, geography, and astronomy is in- 

 debted to his talents, is not easily determined ; 

 but there was scarcely any extensive geodaetical 

 operation undertaken in which his assistance was 

 not solicited ; and there is scarcely an observatory 

 in the world of any notoriety that does not contain 

 some monument of his genius, either executed in 

 the establishment of which he was once the head, 

 or constructed bv other artists in imitation of his 



models. He died on the 12th June, 1835, aged 

 eighty-one. 



TROWBRIDGE; a town of England, in the 

 county of Wilts, situated on an eminence near the 

 river Were, a little above its junction with the 

 Avon, ninety-nine miles W. by S. from London. 

 The inhabitants are employed in the manufacture 

 of woollen cloth, which was introduced here at an 

 early period ; the articles made are chiefly kersey- 

 meres, with some superfine broad cloth. A com- 

 munication is opened with London and Bristol, by 

 means of the Kennet and Avon canal, which passes 

 about a mile north of the town. 



The church, which is dedicated to St James, is 

 a spacious structure, consisting of a nave, chancel, 

 two side aisles, with chapels attached, a north and 

 south porch, and a large tower at the west end, 

 surmounted by a lofty spire ; the nave and aisles 

 are crowned with battlements and crocketed pin- 

 nacles. Here are also places of worship for Bap- 

 tists, Presbyterians, and Methodists. A free-school 

 in which fifty boys are instructed, is supported by 

 property left for charitable purposes. The Rev. 

 George Crabbe, the poet, was rector of this parish 

 for eighteen years, and died here Feb. 3, 1832. 

 Population of town and parish in 1841, 11,050 



TYPE-FOUNDING. In the article Printing, 

 in the body of the work, an account is given of the 

 invention of movable metal types, and their appli- 

 cation to the art of printing. In this place, we 

 have only to describe the manner in which types 

 are made. The metal of which they are formed is 

 an alloy, consisting essentially of four-fifths lead 

 and one fifth regulus of antimony, or three parts 

 lead to one of antimony. The smallest sized types 

 requiring the hardest metal, the alloy for these i 

 twenty-five parts of the regulus of antimony to 

 seventy-five parts of lead : the proportions are 

 varied for the larger sizes, so that in some only 

 fifteen parts of antimony are used to eighty-five of 

 lead. The antimony gives the lead a superior 

 hardness when cast; and as this alloy has the pro- 

 perty of shrinking less than most other metals as 

 it cools, the type receives all the sharpness and 

 finish, which it can acquire, by filling every part 

 of the mould. In making types, the letter is first 

 cut by an artist upon the end of a steel punch, an- 

 swering to the shape of the intended type, or the 

 letter may be formed by hammering down the hol- 

 lows, filing up the edges, and then hardening the 

 soft steel. The punch is then driven into a piece 

 of copper, which forms the matrix, or bottom of 

 the mould intended to produce the letter. As 

 many varieties of punches must be made of steel 

 as there are sizes and species of characters required. 

 In casting, the types are formed with great ra- 

 pidity, owing to the quickness with which the 

 metal cools. The mould in which the types are 

 cast, is composed of two parts. The outer part is 

 made of wood, the inner of steel. At the top it 

 has a hopper-mouth, into which the fused type- 

 metal is poured. The interior cavity is quite 

 uniform, although the mould consists of two divi- 

 sions, because each half, which forms two of the 

 four sides of the letter, is exactly fitted to the 

 other. The matrix is placed at the bottom of the 

 mould, directly under the centre of the orifice, and 

 is held iti its position by a spring. Every letter 

 that is cast can be loosened from the matrix only 

 by removing the pressure on the spring. 



The furnaces of a type foundry are each sur- 

 mounted with an iron pot containing the melted 



