until eleven years old, by which time he had gone through a course
of mensuration, surveying, and navigation. At the age of twelve he
began to teach in the village school, and for the next two or three
years continued to be partially occupied in teaching and in working
on his father's farm. When fifteen years old he removed to Kendal, to
become an assistant in a boarding school established there; and, after
remaining in this capacity for four years, he determined to undertake,
with the assistance of his elder brother, the management of the same
school. Dalton continued to be connected with this school for the next
eight years, during which time he occupied his leisure in studying
Greek, Latin, French, and Natural Philosophy, and was also a frequent
contributor to the 'Gentleman's and Lady's Diaries,' two periodicals
then in considerable repute. While residing at Kendal, Dalton became
acquainted with Mr. Gough, a man who, though blind from infancy, was
yet possessed of high scientific attainments. With this gentleman he
contracted an intimate friendship, and in 1793 was invited, chiefly
through Mr. Gough's favourable recommendation, to join a college,
established in Manchester by a body of Protestant dissenters, as tutor
in the department of mathematics and natural philosophy. He resigned
this appointment after holding it for a period of six years, but
continued to reside in Manchester during the whole of his subsequent
life.
In September 1793 Dalton published his first work, entitled
'Meteorological Observations and Essays,' the materials of which
were, however, collected, and the work entirely completed during his
residence at Kendal. A second edition was printed in 1834, and he
continued to pay much attention to this subject until within a short
period of his death, by which time he had recorded upwards of 200,000
meteorological observations.
In the year 1794 Dalton became a member of the Literary and
Philosophical Society of Manchester, of which, during the course of
his life, he filled in succession all the more important offices;
including that of the presidentship, which he held from the period of
his election in 1817, until his death in 1844. On the 31st of October,
1794, he read his first paper to this Society, entitled, 'Extraordinary
Facts relating to the Vision of Colours,' in which he gives an
account of a singular defect in his own vision, known by the name
of colour-blindness, which rendered him incapable of distinguishing
certain colours, such as scarlet and green. He first became aware of
this defect in his sight from the following circumstance. When a boy he
had gone to see a review of troops, and being surprised to hear those
around him expatiating on the gorgeous effect of the military costume,
he asked, "In what a soldier's coat differed from the grass upon which
he trod," a speech which was received by his companions with derisive
laughs and exclamations of wonder.[16] Until Dalton had announced his
own case, and described the cases of more than twenty persons similarly
circumstanced, this peculiar form of blindness was supposed to be very
rare. In the annals of the above-mentioned Society, Dalton published
a long series of important essays, among the most remarkable of which
are some papers read in the year 1801, entitled, 'Experimental Essays
on the Constitution of Mixed Gases;' 'On the Force of Steam or Vapour
and other liquids at different temperatures in a vacuum and in air;'
'On Evaporation,' and 'On the Expansion of Gases by Heat.' In January
1803 he read to the same Society an inquiry 'On the tendency of Elastic
fluids to diffusion through each other,' and in October of the same
year wrote an Essay containing an outline of his speculations on the
subject of the composition of bodies, in which he gave to the world
for the first time a 'Table of Atomic Weights.' In the following year
he communicated his views on the theory of definite proportions to Dr.
Thomas Thomson, of Glasgow, who at once published an abstract of them;
and in 1808 Dalton himself published the first volume of his new system
of Chemical Philosophy, in which he placed the Atomic Theory on a firm
and clear basis, and established the law of Multiple Proportions. The
value of Dalton's researches on this great subject is immense; by
the promulgation of his views Chemistry became for the first time a
science, and one great law or theory was seen to govern its actions;
before it was a series of separate facts, but by this fundamental law
and its branches, and by this only, it is preserved as a science.
Dalton's theory incurred much opposition before it was finally
accepted by scientific men, and among the unbelievers in it may be
mentioned Sir Humphry Davy. The baronet, however, in the year 1826,
clearly acknowledged and accurately defined Dalton's discoveries in
his anniversary discourse, when he made known that the first award of
the Royal Society's Prize, founded by George IV. in the year before,
would be given to Mr. John Dalton, "for the development of the chemical
theory of Definite Proportions, usually called the Atomic Theory, and
for his various other labours and discoveries in physical and chemical
science."
During his later life Dalton continued to gain his living as
professional chemist, lecturer, and teacher of Chemistry and
Mathematics, and contributed to the advancement of science many
valuable papers chiefly relating to Chemistry; he was also accustomed
in his analytical researches to use the graduated dropping tube,
and may be considered as the originator of analysis by volume. Mr.
Dalton was present at the first meeting of the British Association
held in York in 1831, and continued to feel a lively interest in its
prosperity, and to attend the annual meetings as long as his health
permitted him. On the occasion of the second meeting at Oxford in 1832,
the honorary degree of D.C.L. was conferred upon him, in conjunction
with Faraday, Brown the botanist, and Sir David Brewster. In the summer
of the following year, at the meeting of the same society in Cambridge,
it was announced by Professor Sedgewick, that the King had conferred
on Dalton a pension of 150_l._ per annum, which was increased in 1836
to 300_l._; and as his brother Jonathan died about the same time and
left him heir to the paternal estate, he became comparatively wealthy.
He, however, still continued working according to his strength, and so
late as 1840 published four Essays, entitled, 'On the Phosphates and
Arseniates;' 'Microcosmic Salt;' 'Acids, Bases, and Water;' and 'A New
and Easy Method of Analysing Sugar.' In 1837-8 Dalton was attacked by
paralysis, which greatly enfeebled him; he, however lived till the
year 1844, when a third attack occurred, from which he never recovered,
but died shortly afterwards in his seventy-eighth year.
Dr. R. Angus Smith thus describes Dalton's mode of life while living
with the family of the Rev. W. Johns, of George Street, Manchester,
with whom Dalton continued to reside for twenty-six years: "He rose
at about eight o'clock in the morning; if in winter, went with his
lantern in his hand to his laboratory, lighted the fire, and came over
to breakfast when the family had nearly done. Went to the laboratory
and staid till dinner-time, coming in a hurry when it was nearly
over, eating moderately, and drinking water only. Went out again and
returned about five o'clock to tea, still in a hurry, when the rest
were finishing. Again to his laboratory till nine o'clock, when he
returned to supper, after which he and Mr. Johns smoked a pipe, and the
whole family seems much to have enjoyed this time of conversation and
recreation after the busy day".--_Life of J. Dalton, by William Charles
Henry, M.D., F.R.S., &c._ London, 1854.--_Life of J. Dalton, by Robert
Angus Smith, Ph.D., F.R.S., &c._ London, 1856.
SIR HUMPHRY DAVY, BART., LL.D., P.R.S., &c.,
MEMBER OF THE INSTITUTE OF FRANCE, ETC.
Born December 17, 1778. Died May 30, 1829.
This eminent philosopher was born at Penzance, in Cornwall. As a child
he was remarkably healthy and strong, displaying at the same time
great mental capacity. The first school he ever attended was that of
Mr. Bushell, at which reading and writing only were taught. In these
rudimentary branches of education he soon made such progress, that he
was removed, by the master's advice, to the grammar school kept by the
Rev. Mr. Coryton. He was then only six years old. Here Davy received
the elements of his education until 1793, when he went to the grammar
school of Truro, conducted by the Rev. Mr. Cardew, at which place he
continued for about a year.
Both Davy and his family received much assistance from the
disinterested friendship of Mr. Tonkin, a respectable medical
practitioner at Penzance, who had adopted the mother of Davy and her
sisters, under circumstances of deep distress, extending his kindness
to all her family, particularly to Humphry.
Soon after leaving Dr. Cardew's school, Davy's father died in 1794;
and in the following year Humphry was apprenticed to Mr. Bingham
Borlace, a gentleman at that time practising as surgeon-apothecary in
Penzance. While yet very young, Davy had exhibited traces of an ardent
and inquisitive mind, displaying also a great predilection for poetry;
but from this period he directed his attention more particularly to the
study of chemistry and natural philosophy. His efforts at attaining an
experimental knowledge of the above sciences were, however, greatly
retarded by the defects of his apparatus, which was necessarily very
limited, and consisted chiefly of phials, wine-glasses, tobacco-pipes,
and earthen crucibles. But about this time he had the good fortune
to make the acquaintance of Mr. Davies Giddy Gilbert and Mr. Gregory
Watt,[17] by whose instrumentality the subject of our memoir was
introduced to Dr. Beddoes, who engaged him to superintend a pneumatic
medical institution, which that able but eccentric man had just then
established at Clifton, for the purpose of trying the effects of gases
upon various diseases. This event took place in 1798, Mr. Borlace
readily giving up Davy's indenture, which had not as yet expired.
During his residence at Clifton, Davy was placed in a sphere where his
genius could expand; he was associated with men engaged in similar
pursuits, was provided with suitable apparatus, and enabled to speedily
enter upon that brilliant career of discovery which has rendered his
name illustrious among philosophers.
Soon after he had removed to the neighbourhood of Bristol, Davy's
first published paper, on 'Heat, Light, and Respiration,' appeared
in 'Beddoes' West Country Contributions.' His earliest scientific
discovery was the detection of siliceous earth in the epidermis of
canes, reeds, and grasses.
About the same period, he began to investigate the properties of
gases, and discovered the respirability of nitrous oxide, giving in a
letter to his friend Mr. Davies Gilbert (dated April 16, 1799), the
first intimation of the intoxicating qualities of that gas. Shortly
afterwards he examined its properties more accurately, administering
it to various individuals, and published an account of his discoveries
in a volume entitled 'Researches Chemical and Philosophical chiefly
concerning Nitrous Oxide and its Respiration.' While the favourable
impression from this publication was still fresh on the public mind,
the establishment of the Royal Institution, under the auspices of
Count Rumford, had taken place, and a lecturer of talent was wanting,
to fill the chemical chair. Through the recommendation of Dr. Hope
of Edinburgh, with whom he had become acquainted Davy received the
appointment, and became lecturer to the institution and director of the
laboratory.
It is a singular fact, that although Davy's attention had never
been confined to his favourite science, for he had studied general
literature as well as poetry, yet he was of so uncouth an exterior
and manners, notwithstanding an exceedingly handsome and expressive
countenance, that Count Rumford, a leading director of the Institution,
on seeing him for the first time, expressed no little disappointment,
even regretting the part he had taken in promoting the engagement.
But these feelings were of short duration. Davy was soon sufficiently
humanized, and even refined, to appear before a London and a
fashionable audience of both sexes with great advantage, and by
his ingenuity, and happy facility of illustration, he rendered his
lectures so popular, that at the early age of twenty-two, he found
his company courted by the choicest society of the metropolis. An
anecdote is told illustrative of his popularity, even among the more
humble classes. While passing through the streets one fine night, he
observed a man showing the moon through a telescope to the surrounding
bystanders; Davy stopped to have a look, and having satisfied his
curiosity, tendered a penny to the exhibitor. The man had, however,
in the meanwhile, learnt the name of his customer, and exclaimed,
with an important air, that he could not think of taking money from a
'brother philosopher.' Davy's style of lecturing was animated, clear
and impressive, notwithstanding the naturally inharmonious tones of his
voice; whilst the ingenuity of his happily devised experiments, the
neatness of their execution, and above all the ingenious enthusiasm
which he displayed for his subject, fixed and arrested the attention of
his hearers.
At this time, experimental chemistry began to be the fashion of the
day. Voltaic electricity had just been found to possess extraordinary
powers in effecting the decomposition of chemical compounds; and by
the liberality of the Royal Institution, Davy was put in possession
of a battery consisting of 400 5-inch plates, and one of 40 plates,
1-foot in diameter, with which batteries his early and most brilliant
investigations were conducted.
In 1801 he made his first important discovery, which was communicated
to the Royal Society under the title 'An Account of some Galvanic
Combinations formed by an Arrangement of Single Metallic Plates and
Fluids,' read in June of the same year. In this paper, he showed that
the usual galvanic phenomena might be energetically exhibited by a
single metallic plate, and two strata of different fluids; or that a
battery might be constructed of one metal and two fluids, provided one
of the fluids was capable of oxidizing the surface of the metal. In the
following year to this, Davy was appointed professor to the Board of
Agriculture, and in 1803 was admitted a member of the Royal Society, of
which he became first the secretary, and ultimately the president.
To the 'Philosophical Transactions' of this society he continued to
contribute papers on different branches of experimental philosophy;
and it is on these papers that his claims to celebrity almost entirely
rest. From 1802 to 1805, Davy published several minor papers; but in
the following year appeared his first Bakerian lecture, read to the
Royal Society in November, 1806, in which he detailed the phenomena
of electro-chemical decomposition, and laid down its laws; while in
his second lecture, read in the November following, he announced the
successful application of these principles, and the discovery of the
metallic bases of the fixed alkalies, witnessed by the production of
two new metals, which he named potassium and sodium.[18] This splendid
discovery was fully confirmed by Guy Lussac and Thenard, who, in the
following year, succeeded in decomposing potash by iron filings,
in a red-hot gun barrel. From 1808 to 1810, Davy gave three more
lectures, in which he announced the results of his further chemical
investigations. It may be interesting to remark that the original
batteries of the institution were so worn during the course of his
experiments, as to be unserviceable; a liberal voluntary subscription,
however, amongst the members, in July 1808, put him in possession of
the most powerful voltaic battery ever constructed, consisting of
2000 double plates, with a surface equal to 128,000 square inches.
The results produced by this tremendous power did not, however, add
to science one new fact of any importance. All Davy's great voltaic
discoveries were made before it was in use, and it only served to show
the phenomena of galvanism with greater brilliancy.
Mr. Davy's reputation was now at its height, and he was invited by
the Dublin Society to give a course of lectures on electro-chemical
science. For these lectures, which were commenced on the 8th, and
concluded on the 29th of November, 1810, he received 500 guineas. In
the following year he was invited to give two more courses, on the
Elements of Chemical Philosophy, and on Geology, for which he received
750_l._,--the Provost and Fellows of Trinity College also conferring
on him the degree of LL.D. In 1812, Davy dissolved his connection with
the Royal Institution, by giving a farewell lecture on the 9th of
April; on the preceding day he had received the honour of knighthood
from the hands of the Prince Regent, and on the 11th of the same month
was married to Mrs. Apreece, daughter and heiress of Charles Kerr,
of Kelso, and the possessor of an ample fortune. During the next two
or three years, Sir Humphry communicated several papers to the Royal
Society, but they contained little of importance to science.
Whilst experimenting, in the latter part of 1812, upon azote and
chlorine, he was severely wounded in the eye by the explosion of these
substances; and it is a strong proof of his energy, that when his eye
was sufficiently recovered, he renewed his experiments upon the same
bodies, and was again wounded in the head and hands, but this time
slightly, as he had taken the precaution of defending his face by a
plate of glass.
In the autumn of 1813 he obtained the permission of Napoleon to
travel in France, whither he proceeded, accompanied by his lady and
Mr. Faraday. From France, Davy proceeded to Italy, where he spent the
winter, returning to London on the 23rd of April, 1814. During his stay
in Italy, he collected specimens of the colours used by the ancients
in their pictures. This formed the subject of a memoir to the Royal
Society, the most interesting part of the paper being the announcement
that the fine blues of the ancients were formed of silex, soda, and
copper, and that they may be exactly imitated by strongly heating
together, for the space of two hours, three parts of copper filings,
fifteen of carbonate of soda, and twenty of powdered flint.
In the year 1816, Davy turned his attention to a method of preventing
the dreadful accidents in coal mines, from explosions of the fire-damp.
After considerable investigation, he found that this gas would not
explode when mixed with less than six times or more than fourteen times
its volume of atmospheric air; and in the course of experiments made
for the purpose of ascertaining how the inflammation takes place, he
was surprised to observe that flames will not pass through tubes of a
certain length or smallness of bore. He then found that if the length
was diminished, and the bore also reduced, that flames still would
not pass; and further, that the length of the tubes might safely be
diminished to hardly anything, provided their bore was proportionably
lessened. Working from these principles, he proposed several kinds
of lamps, but all were finally superseded by the simple one known
as the Davy safety-lamp, in which a small oil light is covered by a
cylinder of wire gauze, the small apertures[19] of which flame will
not pass through, and the explosion is thus prevented from extending
outside the wire gauze. The introduction of this beautiful invention,
although freely given to the public, was for a time violently opposed
by prejudice and passion. Experience, however, showed the comparative
safety which the miners who used it possessed, and the coal-owners of
Newcastle and the vicinity presented Davy with a superb service of
plate, as some recognition of the important benefit he had conferred on
them.
During the later years of Sir Humphry Davy's life, various
communications appeared from him to the Royal Society, none, however,
presenting any very remarkable features. In November, 1820, a few
months after the death of Sir Joseph Banks, he was elected president of
the above society. In 1823 he repeated the interesting experiment of
Mr. Faraday, as to the condensation of gases by mechanical pressure,
and succeeded in converting sulphurous acid and prussic acid gases
into liquids, by heating them in strong sealed tubes. During the same
year he investigated the causes of the rapid decay of copper sheathing
on ships, and attributing this to electro-chemical action, succeeded
in preventing it, by attaching plates of iron or zinc to the copper.
This, however, on being tried practically, introduced the unlooked
for evil, of excessive fouling of the bottoms of ships so protected,
which became liable to marine deposits in an equal manner with wooden
bottoms. Davy's plan was thus rendered utterly useless, much to his
mortification.
During the later portion of his life, Sir Humphry was in very infirm
health, and in 1828 he determined to go abroad. Proceeding into Italy,
he fixed his residence at Rome, whence he sent his last communication
to the Royal Society, viz., 'Remarks on the Electricity of the
Torpedo.' The chief peculiarity of this paper was the discovery that
the electricity of this curious creature had no effect on the most
delicate galvanometer. While staying at Rome, Sir Humphry was seized
with a paralytic attack, which greatly alarmed his friends. Shortly
afterwards he left Rome for Geneva, on reaching which city an attack
of apoplexy seized him during the night, which terminated fatally.
The funeral took place on the 1st of June, 1829, with all the honour
and respect the inhabitants of Geneva could testify. His remains were
deposited in the burying-ground of the city, without the walls, the
spot being marked by a simple monument, with a Latin inscription,
erected by Lady Davy.--_Life of Sir H. Davy, by his brother, John Davy,
M.D., F.R.S._ London, 1839.--_Memoir by Dr. Thomas Trail, Encyclopædia
Britannica._--_Weld's History of the Royal Society, with Memoirs of the
Presidents._ London, 1848.--_Brougham's Lives of Philosophers._ London
and Glasgow, 1855.
PETER DOLLOND.
Born February 2, 1731. Died July 2, 1820.