ACCIDENTS BY RAIL AND SEA. 133 



just oue hundred years ago. The cases in point were those of a shoe- 

 maker, named Harris, of Mary-port, in Cumberland, and his brother, 

 master of a merchant- vessel, belonging to the same port. Although the 

 description is very brief, several features, which at a later date charac- 

 terized complete color-blindness, are recognized, and especially in the 

 latter case the type of blindness known at present under the name of 

 red-blindness. 



The first case of color-blindness accurately described, known to us, is 

 that of John Dalton, the celebrated English chemist and physicist. 

 Unable to distinguish red, he studied this defect of nature in himself, 

 and published in 1794 a detailed and accurate description of it.* It is 

 after him that color-blindness received the name of Daltonism, an ap- 

 pellation which appears to have been employed for the first time by 

 Pierre Provost, at Geneva, in 1827, and was, therefore, in use during the 

 life of Dalton, who did not die until 1844. It is not known whether 

 Dalton was aware of this appellation, but, however that may be, he 

 i:»robably would not have objected to this use of his name, for according 

 to George Wilson he was more amused than annoyed by his defect, he 

 himself enjoying the amusement he afibrded others by his mistakes 

 in colors. His countrymen have, however, warmly protested against 

 this manner of immortalizing the memory of Dalton by perpetuating a 

 congenital defect, especially as his scientific merits are sufficient to ren- 

 der his name imperishable. But notwithstanding these protestations, 

 and the universal use in England of the name of color -hlindness, which 

 was first introduced by Sir David Brewster, and is now in general use in 

 Germany {farheblijidheit), the terms Daltonisme and Dalionien are still 

 in common use in France. 



Dalton also cites a number of instances of colorblindness, similar to 

 his own, and later a host of others are mentioned by different authors; 

 but, on the whole, these are isolated cases accidentally encountered, and 

 considered as curiosities, and their most striking features described and 

 discussed, but with no knowledge of how to reduce them to fixed laws. 

 For this purpose, tiiree things were especially wanting: a practical 

 method of investigation, a large material for the purpose, and a satis- 

 factory theory for direction in the employment of this material. 



Seebeck was the first to interest himself especially in systematically 

 collecting a number of cases relatively very large, and in comparing 

 them with each other. In 1837 he made a strict examination of the 

 students of one class in a school in Berlin, and gave a detailed account 

 of twelve cases of complete color-blindness examined by himself, and of 

 one mentioned by his fatlier, as well as a few other instances more or 

 less color-blind, which form the transition between complete color-blind- 

 ness and the normal chromatic sense. Seebeck understood the uncer- 



* Extraordinary facts relating to the vision of colors: with observations by Mr. John 

 Dalton, read October 31st, 1794. Memoirs of the Literary and Philosoiihical Society 

 of Manchester. Vol. v, part i (1798), p. 28. 



