SPECTACLES, MARINER'S COMPASS, BAROMETER, THERMOMETER, WATCHES,
CLOCKS, TELESCOPE, MICROSCOPE, GUNPOWDER, STEAM ENGINE, AND
ELECTRO-MAGNETIC TELEGRAPH.
When were Spectacles invented, and who was their inventor?
It is supposed that they were first known about the thirteenth
century, and invented by a monk of Pisa, in Italy, named Alexander de
Spina. Spectacles are composed of two circular pieces of glass set in
a frame.
What are these glasses called?
Lenses. They are either convex or concave, according to the kind of
sight requiring them. Old people, and those who can only see things at
a distance, from the flatness of the eye, which prevents the rays of
light converging so as to meet in the centre, require convex lenses.
People who can only distinguish objects when viewed closely, from the
eye being too convex, require concave lenses to counteract it by
spreading the rays, and thus rendering vision distinct.
_Convex_, rising outwardly in a circular form; opposite to
concave.
_Concave_, hollow; round, but hollow, as the inner curve of
an arch, &c.
_Converging_, tending to one point from different parts.
_Vision_, the faculty of seeing.
What is the Mariner's Compass?
A most useful and important instrument, by the aid of which the
navigator guides his ship on the sea, and steers his way to the place
of his destination. The inventor of the Mariner's Compass is not
known, nor the exact time of its introduction; it was employed in
Europe in navigation about the middle of the thirteenth century, and
has been in use more than five hundred years. The Chinese are said to
have been acquainted with it much earlier, but no reliance can be
placed on their dates. The power of the loadstone to attract iron was
known to the ancient Egyptians, but it was not applied to any
practical purpose.
_Navigator_, one who guides a ship.
_Steer_, to direct or guide a vessel in its course.
_Destination_, the place to which a person is bound.
_Practical_, capable of practice, not merely speculative.
What is the Loadstone?
An ore of iron which possesses the peculiar property of attracting
iron, namely, of drawing it in contact with its own mass, and holding
it firmly attached by its own power of attraction. A piece of
loadstone drawn several times along a needle, or a small piece of
iron, converts it into an artificial magnet; if this magnetized needle
is carefully balanced, it will turn round of itself, till its end
points towards the North. The magnetized needle also possesses the
power of attracting iron, and of communicating this power to another
piece of iron or steel, similar to that of the loadstone itself.
_Contact_, touch.
_Magnetized_, rendered magnetic.
Describe the Mariner's Compass.
The Mariner's Compass consists of a circular box, enclosing a
magnetized bar of steel, called the _needle_, carefully balanced on an
upright steel pivot, and having that end which points to the North
shaped like the head of an arrow; attached to this needle, and turning
with it, is a card on which are printed the divisions of North, South.
East, and West; called the points of the compass. By simply looking at
the position of the needle, the mariner can see the direction in which
his vessel is sailing, and regulate his helm accordingly.
_Helm_, the instrument by which a ship is steered,
consisting of a rudder and tiller.
What is a Barometer?
An instrument for measuring the weight of the atmosphere, which
enables us to determine the changes of the weather, the height of
mountains, &c. It consists of a glass tube hermetically sealed at one
end, filled with mercury, and inverted in a basin of mercury;
according to the weight of the atmosphere, this mercury rises or
falls.
How is the Hermetic seal formed?
By heating the edges of a vessel, till they are just ready to melt,
and then twisting them closely together with hot pincers, so that the
air may be totally excluded. The word is taken from Hermes, the Greek
name for Mercury, the heathen god of arts and learning, and the
supposed inventor of chemistry,[9] which is sometimes called the
hermetical art; or perhaps from Hermes, an ancient king of Egypt, who
was either its inventor, or excelled in it.
[Footnote 9: See Chapter XVIII., article Chemistry.]
What is Mercury?
Quicksilver, or mercury, is a white fluid metal, the heaviest except
platina and gold; it readily combines with nearly all other metals,
and is used in the manufacture of looking-glasses, barometers,
thermometers, &c.; in some of the arts, and in the preparation of
several powerful medicines. It is found in California, Hungary,
Sweden, Spain, China, and Peru. The quicksilver mine of Guança Velica,
in Peru, is one hundred and seventy fathoms in circumference, and four
hundred and eighty deep. In this profound abyss are seen streets,
squares, and a chapel, where religious worship is performed. The
quicksilver mines of Idria, a town of Lower Austria, have continually
been wrought for more than 300 years. The vapor which is continually
arising from the mercury is very hurtful to the miners, who seldom
survive many years.
_Abyss_, a gulf, a depth without bottom.
In what state is Mercury usually found?
Either native, or in the form of ore; it is often found mixed with
silver, but more frequently with sulphur in the form of sulphuret,
which is decomposed by distillation. Running mercury is found in
globules, in America, and is collected from the clefts of the rocks.
Mercury has the appearance of melted silver; it is neither ductile nor
malleable in this state; it is a substance so volatile, when heated,
that it may be evaporated like water; it is always seen in a fluid
state, even in temperate climates, as a very small portion of heat is
sufficient to preserve its fluidity. It is used to separate gold and
silver from the foreign matter found with those metals. Calomel, a
valuable medicine, and vermilion, a color, are both preparations of
mercury.
_Globules_, small particles of matter having the form of a
ball or sphere.
What is a Thermometer?
An instrument for measuring temperature. It consists of a fine glass
tube, terminated at one end in a bulb, usually filled with mercury,
which expands or contracts according to the degree of heat or cold. On
the scale of the Fahrenheit thermometer, the freezing point of water
is marked 32° and the boiling point at 212°. In both the Centigrade
and the Reaumur scales the freezing point is at 0, and the boiling
point at 100° in the Centigrade and at 80° in Reaumur's. The invention
of this instrument dates from about the close of the sixteenth
century; but it is not known by whom it was first brought into use.
_Terminated_, finished, ended.
When and by whom were Watches and Clocks invented?
Watches were invented about the year 1500, but who was the inventor is
disputed. They were, however, of little value as time-keepers, before
the application of the spiral spring as a regulator to the balance;
the glory of this excellent invention lies between Dr. Hooke and M.
Huygens; the English ascribing it to the former, the Dutch, French,
&c., to the latter. Some assert that pocket-watches were first made
about 1477, at Nuremberg, in Germany. The most ancient clock of which
we possess any certain account, was made in 1634 by Henry de Wycke, a
German artist; it was erected in a tower of the palace of Charles V.,
king of France. The pendulum was applied by Huygens, in 1656.
What is a Pendulum?
A weight so suspended from a fixed point that it may easily swing
backward and forward; its oscillations are always performed in equal
times, provided the length of the pendulum and the gravity remain the
same. It is said that the idea of employing the pendulum for the
measurement of time, was first conceived by Galileo, while a young
man, upon his observing attentively the regular oscillations of a lamp
suspended from the roof of a church in Pisa. It was not, however, till
the time of Huygens that a method was devised of continuing its
motions, and registering the number of its oscillations.
_Oscillation_, a swinging backward and forward.
_Gravity_, the tendency of a body toward the centre of the
earth.
_Registering_, recording.
[Illustration: CHARCOAL BURNING.]
[Illustration: GOLD MINERS WASHING ORE.]
To whom is the invention of Gunpowder ascribed?
Most authors suppose it was invented by Bartholdus Schwartz, a monk of
Goslar, a town of Brunswick, in Germany, about the year 1320; it
appears, however, that it was known much earlier in many parts of the
world, and that the famous Roger Bacon, who died in 1292, knew its
properties; but it is not certain that he was acquainted with its
application to fire-arms.
Who was Roger Bacon?
A learned Franciscan, born at Ilchester, England, in 1214. He studied
at Oxford, and afterwards became professor at that great University.
He was familiar with every branch of human knowledge, but was
especially distinguished for his extraordinary proficiency in the
natural sciences. To him we owe the invention of the telescope; that
of gunpowder is ascribed to him, as stated above, although we have no
evidence to show whether he discovered its ingredients himself, or
whether he derived the knowledge from some ancient manuscripts. Bacon
suffered some from the ignorance of the age in which he lived, many of
his experiments being looked upon as magic. He died at Oxford in the
year 1294.
What is understood by Magic?
Magic is a term used to signify an unlawful and wicked kind of
science, depending, as was pretended, on the assistance of superhuman
beings and of departed souls. The term was anciently applied to all
kinds of learning, and in particular to the science of the Magi or
Wise Men of Persia, from whom it was called magic. _Natural_ magic is
no more than the application of natural active causes to passive
things or subjects, to produce effects apparently supernatural.
_Supernatural_, beyond the powers of nature; miraculous.
Of what is Gunpowder composed?
Of saltpetre,[10] sulphur, and charcoal, mixed together and powdered;
its explosive force when fired, is owing to the instantaneous and
abundant liberation of gaseous matter by the intense heat resulting
from the action of the combustibles upon the saltpetre. It is not
known by whom it was first applied to the purposes of war, but it is
certain that it was used early in the fourteenth century. Cannons were
used at the battle of Cressy, in 1346; small guns, or muskets, were
introduced into the Spanish army in 1521.
[Footnote 10: See Chapter XIII.]
_Explosive_, bursting out with violence and noise.
_Liberation_, a setting at liberty.
Is not Gunpowder highly combustible?
So combustible is gunpowder, that a single spark of fire, lighting
upon any of it, will cause it to explode with immense force; and
instances have occurred, when any store or magazine of it has taken
fire, that have been attended with the most fatal effects. It is
useful to the miner and engineer as a ready means of overcoming the
obstacles which are presented in their search for mineral treasures,
and in procuring materials for building. From many passages in the
ancient authors, there is reason to suppose that gunpowder, or a
composition extremely like it, was known to them; but it does not
appear to have been in general use, and the invention of fire-arms is
comparatively modern. Dynamite, a recent invention, has a still
greater explosive force than gunpowder.
_Engineer_, one who works or directs an engine.
_Obstacles_, hinderances, obstructions.
What is Saltpetre?
A bitter kind of salt, called by the ancients nitre, but more commonly
among us saltpetre. It is composed of nitric acid and potassa.[11] It
is found in earthy substances; sometimes native or pure, in the form
of a shapeless salt. Vast quantities are found in several of the
marly earths of the East Indies, China, Persia, and also in South
America. In India it is found naturally crystallized, and forming thin
crusts upon the surface of the earth. It is especially abundant in the
United States, being found in immense quantities in the limestone
caves in the south-western States.
[Footnote 11: See Potash, Chapter VII., article Glass.]
What do you mean by _Marly_?
Consisting of marl, a kind of earth composed of different proportions
of clay and carbonate of lime; it is much used for manure. There are
several different-colored marls, each possessing different qualities.
The most common are the red and the white, though there are grey,
brown, blue, and yellow colored marls.
What is a Telescope?
An optical instrument, which serves for discovering and viewing
distant objects, either directly by glasses, or by reflection. The
invention of the telescope is one of the noblest and most useful of
which modern ages can boast, since by means of this instrument the
wonderful motions of the planets and fixed stars, and all the heavenly
bodies, are revealed to us. The honor of the invention is much
disputed; it is certain, however, that the celebrated Galileo was the
first who improved the telescope so as to answer astronomical
purposes. The name is formed from two Greek words, one signifying
_far_, the other _to observe_.
_Optical_, relating to Optics, the science of vision.
_Astronomical_, relating to Astronomy.
Who was Galileo?
A most eminent astronomer and mathematician, born at Florence, in
Italy. His inventions and discoveries in Astronomy, Geometry, and
Mechanics, contributed much to the advancement of those sciences. He
died in 1642.
_Astronomer_, one versed in Astronomy.
_Mathematician_, one versed in Mathematics; a science which
treats of magnitude and number.
What is Astronomy?[12]
That science which teaches the knowledge of the heavenly bodies, with
the nature and causes of their various phenomena.
[Footnote 12: See Chapter xviii.]
What is Geometry?
An ancient, perfect, and beautiful science, which treats of the
relations and properties of lines, surfaces, and solids.
What is meant by Mechanics?
The science which investigates the laws of forces and powers, and
their action on bodies, either directly or by machinery. When the term
_mechanic_ is applied to a _person_, it means one skilled in
mechanics, accustomed to manual labor.
_Investigate_, to search, to inquire into.
_Manual_, performed by the hand.
What is a Microscope?
An optical instrument, by means of which very minute objects are
represented exceedingly large, and viewed very distinctly according to
the laws of refraction or reflection. Nothing certain is known
respecting the inventor of microscopes, or the exact time of their
invention, but that they were first used in Germany, about 1621.
_Minute_, small, diminutive.
_Refraction_, a change in the direction of a ray of light,
when it passes through transparent substances of different
densities.
_Reflection_, a turning back of a ray of light after
striking upon any surface.
What is the Steam Engine?
A machine that derives its moving power from the force of the steam
produced from boiling water, which is very great, especially when, as
in the steam engine, it is confined within a limited compass: this
useful machine is one of the most valuable presents that the arts of
life have received from the philosopher, and is of the greatest
importance in working mines; supplying cities with water; in working
metals; in many mechanical arts; and in navigation. By the aid of
steam, vessels are propelled with greater swiftness than those which
are wholly dependent on the winds and tides; and thus trade is
facilitated, and we are enabled to communicate with distant lands in a
much shorter space of time than was formerly consumed. On land,
railroads are constructed, on which steam carriages run with
astonishing rapidity, so that a journey which by coach and horses
formerly required two or more days, may now be performed in four or
five hours.
_Mechanical_, belonging to Mechanics.
To whom are we indebted for its invention?
Its invention is by most writers ascribed to the Marquis of Worcester,
an Englishman, about 1663; but it does not appear that the inventor
could ever interest the public in favor of this, or his other
discoveries. The steam engine of Captain Savery, also an Englishman,
is the first of which any definite description has been preserved. It
was invented in 1698. Since that period it has been successively
improved by various persons, but it is to Mr. Watt and Mr. Boulton, of
England, that it is indebted for much of its present state of
perfection.
By whom was the Steam Engine first applied to the purposes of
Navigation?
By John Fitch, of Pennsylvania. From papers in the historical
collections of Pennsylvania, it appears that the first successful
experiments were made at Philadelphia, in 1785, three years before the
attempts at Falkirk, and on the Clyde, in Scotland. The boat made
several trips on the Delaware and Schuylkill rivers, but owing to
repeated accidents to her machinery, and the want of funds and
competent mechanics for the necessary repairs, she was abandoned. In
1807, Robert Fulton, also of Pennsylvania, made his first experimental
trip on the Hudson River, with complete success. To this distinguished
and ingenious American justly belongs the honor of having brought
navigation by steam to a state of perfection. In 1819, the first
steamship crossed the Atlantic from Savannah to Liverpool; and in
1838, a regular communication by steamship was established between
Great Britain and the United States. Since that period, ocean
navigation by steam-vessels has made rapid progress, and, at the
present time, numbers of steamers connect our various seaports with
those of other nations, and with each other.
What is the Electro-Magnetic Telegraph?
An instrument, or apparatus, by means of which intelligence is
conveyed to any distance with the velocity of lightning. The electric
fluid, when an excess has accumulated in one place, always seeks to
transfer itself to another, until an equilibrium of its distribution
is fully restored. Consequently, when two places are connected by
means of a good conductor of electricity, as, for instance, the
telegraphic wire; the fluid generated by a galvanic battery, if the
communication be rendered complete, instantaneously traverses the
whole extent of the wire, and charges, at the distant station, an
electro-magnet; this attracts one end of a lever, and draws it
downward, while the other extremity is thrown up, and, by means of a
style, marks a slip of paper, which is steadily wound off from a
roller by the aid of clock-work. If the communication is immediately
broken, only one wave of electricity passes over, and a _dot_ is made
upon the paper; if kept up, a _line_ is marked. These dots and lines
are made to represent the letters of the alphabet, so that an operator
employed for the purpose can easily read the message which is
transmitted.--The Electro-Magnetic Telegraph was first introduced upon
a line between Baltimore and Washington, by Professor Morse, in 1844;
at the present time, it is in successful operation between nearly all
the important cities and towns of the United States and of Europe.
An _Electro-Magnet_ is a piece of soft iron, rendered
temporarily magnetic by being placed within a coil of wire
through which a current of electricity is passing.