CHEMISTRY OF THE NINETEENTH CENTURY. 597 



having lived twelve years at Kendal, Dalton in 1793 removed to 

 Manchester to enter upon the appointment of Lecturer of Mathematics 

 and Natural Philosophy at a college which certain Nonconformists ' 

 had recently established at Manchester. The emoluments of the 

 office, apart from the " commons and rooms in the college," did not 

 amount to more than fifty guineas a year clear money. The duties, 

 however, required for their performance only twenty-one hours each 

 week, and the time which might be requisite for the preparation of 

 each lecture. The total number of students attending the " New 

 College " in the first session of his residence there is mentioned by 

 Dalton as twenty-six. A paragraph from a letter of his, dated " 2nd 

 mo., 2oth, 1794," may be quoted as a little picture of a philosopher 

 in his study. 



"There is in this town a large library furnished with the best books in every art, 

 science, and language, which is open to all, gratis ; when thou art apprised of this and 

 suchlike circumstances, thou considerest me in my private apartments, undisturbed, 

 having a good fire and a philosophical apparatus around me, thou wilt be able to form 

 an opinion whether I spend my time in slothful inactivity of body and mind. The 

 watchword for my retiring to rest is, ' Past 12 o'clock cloudy morning.' "* 



Soon after his arrival in Manchester, Dalton became a member of 

 the Literary and Philosophical Society of Manchester, an association 

 which has always exhibited no small degree of vitality, and whose 

 records probably include a greater number of papers of high impor- 

 tance than those of any other scientific organization of a similar extent. 

 On the 3ist of October, 1794, Dalton read his first paper before the 

 members of this society. Its title was " Extraordinary Facts relating 

 to the Vision of Colours, with Observations/' and in it he describes 

 his own colour blindness. This phenomenon had before this time been 

 little noticed ; but it has since been a theme of much discussion and 

 experiment. Interesting as are the facts connected with this subject, 

 they must here be passed over. From October, 1794, to April, 1844, 

 Dalton contributed to the journals of the Manchester society no fewer 

 than 116 papers. He contributed likewise many papers to other sci- 

 entific journals, and issued several independent publications, the most 

 important of which was his " New System of Chemical Philosophy," 

 the first part of which appeared in 1808, the second part in 1810. In 

 1800 Dalton was elected to the secretaryship of the Literary and 

 Philosophical Society of Manchester, in 1808 he became the vice- 

 president, and in 1817 he was made president, and filled the chair 

 during the rest of his lifetime. All the various academical distinctions 

 that can fall to the lot of a man of science were conferred upon Dalton 



* For the benefit of younger readers it may be explained that the last words refer to 

 one of the functions of the old watchmen, who were superseded by our present well- 

 organized police force. It was one of the duties assigned to these old worthies, when 

 on their beats during the night, to proclaim aloud the hour and the state of the weather. 



