May 14.--This is the birth-day of GABRIEL DANIEL FAHRENHEIT, usually
regarded as the inventor of the common mercurial thermometer, and
certainly the first person by whom the instrument was accurately
constructed. Fahrenheit was born at Dantzic, in 1686. His business was
that of a merchant, but he was fond of spending his leisure in
philosophical inquiries and experiments; and at last he settled at
Amsterdam, and devoted himself almost entirely to the fabrication of the
instrument which bears his name, and which still continues to be the
thermometer principally used in Britain, North America, and Holland. He
is supposed to have begun to make these thermometers about the year
1720, and he died in 1736. It was Fahrenheit, also, who first noticed
the fact that water boils at different degrees of temperature, according
to the weight of the atmospheric column resting upon it--that it
requires, for instance, less heat to make it boil on the summit than at
the foot of a high mountain. We shall, in some future number, explain
the construction and principle of the thermometer. In the mean time we
extract from ‘the Companion to the Almanac’ for 1830, a comparison of
the various scales of the thermometer which are in general use:--
“A fertile cause of error in estimating and comparing the statements of
temperature, is the very different manner in which they are recorded by
scientific men of different nations. Wherever the English language
prevails, the graduation of _Fahrenheit_ is generally preferred. By the
German authors, Römer (Reaumur) is used; and the French have, within a
few years, decided to adopt that of Celsius, a Swedish philosopher,
calling it ‘_Thermomètre Centigrade_.’ To diminish this evil, in some
degree, the annexed diagram has been constructed, which shows by
inspection, the expression of any point of temperature in the degrees of
either or of all the above-mentioned scales; and the comparison of any
degree of one with the equivalent degrees of the others.”
[Illustration: A thermometer, with markings for the Reaumur,
Fahrenheit, and Celsius scales. The following temperatures are marked,
most with degrees Fahrenheit: Highest Temp. Sun’s rays at London, 134°;
Highest Temp. of the Air at ditto, 90°; Mean Temp. of ditto at ditto,
49 and a half°; Lowest Temp. of ditto at ditto, 11°; Ditto at the
Earth’s surface at ditto, 5°; Greatest cold observed in the shade in
England; Boiling point of water; Boiling point of alcohol, 174° (both
at 30 inches barometric pressure); melting points of beeswax (142°) and
tallow (127°); Fever heat as usually marked; Fever heat in general,
107°; Blood heat; Summer heat; Temperate; Usual Temp. of Spring water,
50°; Water freezes; Strong wine freezes, 20°.]
May 16.--On this day, in the year 1623, was born at Rumsey, in
Hampshire, the celebrated Sir WILLIAM PETTY, a memorable and animating
example of the elevation and distinction which real talent, accompanied
by activity and perseverance, has always in this country been able to
command for its possessor. Petty’s father was a clothier, and he appears
to have given his son little to set out in life with but a good
education. It is said that Petty, when quite a boy, took great delight
in spending his time among smiths, carpenters, and other artificers, so
that at twelve years old he knew how to work at their trades. He made so
great progress at the grammar-school, that at fifteen he had made
himself master of French, Latin, and Greek, and understood something of
mathematics and physical science. On entering the world, he went to Caen
in Normandy with a little stock of merchandize, which he there improved;
and on his return to England, having obtained some employment connected
with the navy, he managed to save about sixty pounds before he was
twenty years of age; and with this sum he repaired to the Continent, to
study medicine at the foreign universities. He accordingly attended the
requisite classes successively at Leyden, Utrecht, and Paris; and in
about three years came home well qualified to commence practising as a
physician. Having taken up his residence in this capacity at Oxford, he
soon acquired for himself a distinguished reputation, and, young as he
was, was appointed assistant professor of anatomy in the University. He
had already also become known in the scientific world by some mechanical
inventions of considerable ingenuity; and he was one of the club of
inquirers who, about the year 1649, began to assemble weekly at Oxford,
for philosophical investigations and experiments, and out of whose
meetings eventually arose the present Royal Society. Indeed, Dr. Wallis,
one of the members, in a letter, in which he has given an account of the
association, tells us that their meetings were first held “at Dr.
Petty’s lodgings, in an apothecary’s house, because of the convenience
of inspecting drugs, and the like, as there was occasion.” Petty’s
reputation, however, rose so rapidly that, after having succeeded first
to the professorship of anatomy in the University, and then to that of
music in Gresham College, he was, in 1652, appointed physician to the
forces in Ireland. This carried him over to that country--and eventually
introduced him to a new career. In 1655 we find him appointed secretary
to the Lord Lieutenant, and three years afterwards a member of the House
of Commons. He was, however, soon after removed from his public
employments by the Parliament which met after the death of the
Protector. On the Restoration, which took place the following year, he
was made a commissioner of the Court of Claims. The remainder of his
life was as busy as the portion of it already passed had been; but we
have no room to enumerate the books he wrote, the ingenious schemes and
inventions with which his mind was constantly teeming, and the lucrative
speculations in mining, the manufacture of iron, and various other great
undertakings, in which he engaged. Suffice it to say, that, after
accumulating a large property, he died in London, on the 16th of
December, 1687, full of honours, if not of years. The first Marquis of
Lansdowne (the father of the present Marquis) was the great-grandson of
Sir William Petty.
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