During this time Dalton employed his leisure in learning Latin, Greek and French, and in pursuing his studies in mathematics and natural philosophy. He became a frequent contributor to the Gentlemen's Diary, a paper which received problems of various kinds—chiefly mathematical—and presented prizes for their successful solution.
Besides setting and answering mathematical problems in this journal, and also in the Ladies' Diary, Dalton sometimes ventured into the wider fields of mental phenomena. It seems strange to read that, even at the age of twenty-six, Dalton should occupy his leisure time composing answers to such queries as these:—
"Whether, to a generous mind, is the conferring or receiving an obligation, the greater pleasure?"
"Is it possible for a person of sensibility and virtue, who has once felt the passion of love in the fullest extent that the human heart is capable of receiving it (being by death or some other circumstance for ever deprived of the object of its wishes), ever to feel an equal passion for any other object?"
In his answer to the second of these queries, Dalton carefully framed two hypotheses, and as carefully drew conclusions from each. The question in the Diary was by "Mira;" if "Mira" were a "rapturous maiden" she would not derive much comfort from the cold and mathematical answer by "Mr. John Dalton of Kendal."
At Kendal Dalton made the acquaintance of Mr. Gough, who was about eight years older than Dalton, and had been blind from the age of two. Mr. Gough, we are assured by Dalton, was "a perfect master of the Latin, Greek and French tongues;" he understood "well all the different branches of mathematics;" there was "no branch of natural philosophy but what he was well acquainted with;" he knew "by the touch, taste and smell, almost every plant within twenty miles of Kendal." To the friendship of this remarkable man Dalton owed much; with his help he acquired a fair knowledge of the classical languages, and he it was who set Dalton the example of keeping a regular record of weather observations.
On the 24th of March 1787 Dalton made his first entry in a book which he entitled "Observations on the Weather, etc.;" the last entry in this book he made fifty-seven years later on the evening preceding his death. The importance of Dalton's meteorological observations, as leading him to the conception of the atomic theory, will be noticed as we proceed.
In the year 1793 Dalton, who was now twenty-seven years of age, was invited to Manchester to become tutor in the mathematical and natural philosophy department of a college recently established by influential Dissenters in that town. Eighty pounds for the session of ten months was guaranteed him; and he was provided with "rooms and commons" in the college at a charge of £27 10s. per session.
He held this appointment for six years, when he retired, and continuing to live in Manchester devoted himself to researches in natural philosophy, gaining a living by giving private lessons in mathematics and physical science at a charge of 2s. 6d. per hour, or 1s. 6d. each if more than two pupils attended at the same time.
Dalton was elected a Fellow of the Literary and Philosophical Society of Manchester in the year 1794; and from the time of his retiring from the tutorship of Manchester New College till the close of his life he spent a great part of his time in a room in the society's house in George Street, in studying and teaching. The fifty years thus spent are marked by few outward events. The history of Dalton's life from this time is the history of the development of his intellect, and the record of his scientific discoveries.