Part 7 (2/2)

_John Dalton_, 1766-1844.

The progress of chemical knowledge became so rapid in the early years of the present century, that although I have in this chapter called the time immediately succeeding that of Lavoisier ”the period of John Dalton,” and although I shall attempt to describe the advances made by this philosopher without considering those of his contemporaries Davy and Berzelius, yet I must insist on the facts that this arrangement is made purely for the sake of convenience, and that many of the discoveries of Davy, Berzelius and others came in order of time before, or followed close upon the publication of Dalton's atomic theory.

Nevertheless, as the work of these men belongs in its essence to the modern period, and as the promulgation of the atomic theory by Dalton marks the beginning of this period, it seems better that we should have a clear conception of what was done by this chemist before proceeding to consider the advances made by his contemporaries and successors.

JOHN DALTON, the second of three children of Joseph and Deborah Dalton, was born at Eaglesfield, a village near c.o.c.kermouth, in c.u.mberland, on the 5th of September 1766. One of the first meeting-houses established by the Society of Friends is to be found in Eaglesfield.

The Dalton family had been settled for several generations on a small copyhold estate in this village. The first of them to join the Friends was the grandfather of John Dalton; his descendants remained faithful adherents of this society.

Dalton attended the village schools of Eaglesfield and the neighbourhood until he was eleven years old, by which time, in addition to learning reading, writing and arithmetic, he had ”gone through a course of mensuration, surveying, navigation, etc.” At the age of ten his taste for measurements and calculations began to be remarked by those around him; this taste was encouraged by Mr. Robinson, a relative of Dalton, who recognizing the indomitable perseverance of the boy appears to have taken some care about this time in directing his mathematical studies.

At the early age of twelve Dalton affixed to the door of his father's house a large sheet of paper whereon he announced that he had opened a school for youth of both s.e.xes; also that ”paper, pens and ink” were sold within.

The boy-teacher had little authority over his pupils, who challenged their master to fight in the graveyard, and broke the windows of the room into which they had been locked till their tasks should be learned.

When he was fifteen years old Dalton removed to Kendal, where he continued for eleven or twelve years, at first as a.s.sistant-master, and then, along with his elder brother Jonathan, as princ.i.p.al of a boarding school for boys.

It was announced by the brothers that in this school ”youth will be carefully instructed in English, Latin, Greek and French; also writing, arithmetic, merchants' accounts and the mathematics.” The school was not very successful. Both brothers were hard, inflexible, and ungainly in their habits, and neither was fitted to become a successful teacher of boys: of the two, John had the gentler disposition, and was preferred by the boys; ”besides, his mind was so occupied by mathematics that their faults escaped his notice.”

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 pa.s.sion of love in the fullest extent that the human heart is capable of receiving it (being by death or some other circ.u.mstance for ever deprived of the object of its wishes), ever to feel an equal pa.s.sion 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 a.s.sured 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 friends.h.i.+p of this remarkable man Dalton owed much; with his help he acquired a fair knowledge of the cla.s.sical 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 ent.i.tled ”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 10_s._ 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 2_s._ 6_d._ per hour, or 1_s._ 6_d._ 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 tutors.h.i.+p 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.

On one occasion during Dalton's stay at Kendal, as he was about to make a visit to his native village, he bethought himself that the present of a pair of silken hose would be acceptable to his mother. He accordingly purchased a pair marked ”newest fas.h.i.+on;” but his mother's remark, ”Thou hast brought me a pair of grand hose, John; but what made thee fancy so light a colour? I can never show myself at meeting in them,” rather disconcerted him, as to his eyes the hose were of the orthodox drab colour.

His mother insisted that the stockings were ”as red as a cherry.” John's brother upheld the ”drab” side of the dispute; so the neighbours were called in, and gave their decision that the hose were ”varra fine stuff, but uncommon scarlety.”

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