APPENDIX I: INVENTIONS 443 



and Hall and Dolland had succeeded in correcting chromatic aberra- 

 tion in telescope objectives by the combination of crown and flint 

 glass, in the eighteenth century. 



Amici, of Modena, in 1812, Fraunhofer of Munich in 1816, Tully 

 of London in 1824, J. J. Lister in 1830 and others gradually per- 

 fected the achromatic microscope objective, so that about 1835 really 

 excellent instruments became accessible to microscopical investiga- 

 tors. The numerous discoveries in cellular biology and in pathology 

 which soon followed testify to the extent and importance of these 

 improvements. 



ILLUMINATING GAS, made by the destructive distillation of coal, 

 was invented and introduced in 1792 by William Murdock, who in 

 1802 had so far perfected the process that even the exterior of his 

 factory in Birmingham was illuminated with gas in celebration of the 

 peace of Amiens. 



FRICTION MATCHES, were preceded early in the nineteenth century 

 by splinters of wood coated with sulphur and tipped with a mixture 

 of chlorate of potash and sugar. These when touched with sulphuric 

 acid ignited. It was not, however, until 1827 that practical friction 

 matches were made and sold. These were known, after their inventor, 

 as "Congreves" and consisted of wooden splints coated with sulphur 

 and tipped with a mixture of sulphide of antimony, chlorate of potash, 

 and gum. When subjected to severe friction, specially arranged for, 

 these took fire. The phosphorus friction match was introduced 

 commercially in 1833. 



THE SEWING-MACHINE. Very few labor-saving inventions sur- 

 pass in efficiency sewing-machines. These also were invented in 

 the nineteenth century and had a gradual development, in which 

 various inventors participated. The first which need be mentioned 

 was that of a French tailor, named Thimonier, patented in 1830. 

 It is said that although made of wood and clumsy, eighty of these 

 machines were in use in Paris in 1841, when an ignorant mob wrecked 

 the establishment in which they were located and nearly murdered 

 the inventor. The most important ideas embodied in modern ma- 

 chines are, however, of strictly American origin, the work of Walter 

 Hunt of New York, and of Elias Howe of Spencer, Massachusetts 

 being of principal importance (1846). Other Americans, especially 

 Singer, Grover, Wilson and Gibbs, afterwards contributed to the 

 present excellence and variety of the sewing-machine. 



