HOROLOGY AND INSTRUMENTS OF PRECISION.
“Time measures all things, but I measure it.”
So far as we at present know there were four forms of time-measuring
instruments known to antiquity--the sun-dial, the clepsydra or water
clock, the hour-glass, and the graduated candle.
The sun-dial, by which time was measured by the shadow cast from a pin,
rod or pillar upon a graduated horizontal plate--the graduations
consisting of twelve equal parts, in which the hours of the day were
divided, were, both as to the instrument and the division of the day
into hours, invented by the Babylonians or other Oriental race, set up
on the plains of Chaldea, constructed by the Chinese and Hindoos--put
into various forms by these nations, and adapted, but unimproved, by the
learned Greeks and conquering Romans. It appears to have been unknown to
the Assyrians and Egyptians, or if known, its knowledge confined to
their wise men, as it does not appear in any of their monuments.
The clepsydra, an instrument by which in its earliest form a portion of
time was measured by the escape of water from a small orifice in the
bottom of a shell or vase, or by which the empty vase, placed in another
vessel filled with water, was gradually filled through the orifice and
which sank within a certain time, is supposed by many to have preceded
the invention of the sun-dial. At any rate they were used
contemporaneously by the same peoples.
In its later form, when the day and night were each divided into twelve
hours, the vessel was correspondingly graduated, and a float raised by
the inflowing water impelled a pointer attached to the float against the
graduations.
Plato, it is said, contrived a bell so connected with the pointer that
it was struck at each hour of the night. But the best of ancient
clepsydras was invented by Ctesibius of Alexandria about the middle of
the third century B. C. He was the pupil of Archimedes, and adopting his
master’s idea of geared wheels, he mounted a toothed wheel on a shaft
extending through the vessel and carrying at one end outside of the
vessel a pointer adapted to move around the face of a dial graduated
with the 24 hours. The vertical toothed rod or rack, adapted to be
raised or lowered by a float in a vessel gradually filled with water,
engaged a pinion fixed on another horizontal shaft, which pinion in turn
engaged the larger wheel. It was not difficult to proportion the parts
and control the supply of water to make the point complete its circuit
regularly. Then the same inventor dispensed with the wheel, rack, and
pinion, and substituted a cord to which a float was attached, passing
the cord over a grooved pulley and securing a weight at its other end.
The pulley was fixed on the shaft which carried the hour hand. The float
was a counterbalance to the weight, and as it was lifted by the water
the weight stretched the cord and turned the pulley, which caused the
pointer to move on the dial and indicate the hour. The water thus acted
as an escapement to control the motive power. In one form the water
dropped on wheels which had their motion communicated to a small statue
that gradually rose and pointed with a rod to the hour upon the dial.
Thus the essential parts of a clock--an escapement, which is a device to
control the power in a clock or watch so that it shall act
intermittently on the time index, a motive power, which was then water
or a weight, a dial to display the hours, and an index to point them
out--were invented at this early age. But the art advanced practically
no further for many centuries.
The hour-glass is too familiar to need description.
The incense sticks of the Chinese, the combustion of which proceeded so
slowly and regularly as to render them available for time measures, were
the precursors of the graduated candles.
With the ungraduated sun-dial the Greeks fixed their times for bathing
and eating. When the shadow was six feet long it was time to bathe, when
twice that length it was time to sup. The clepsydra became in Greece a
useful instrument to enforce the law in restricting loquacious orators
and lawyers to reasonable limits in their addresses. And in Rome the
sun-dials, the clepsydras and the hour-glass were used for the same
purpose, and more generally than in Greece, to regulate the hours of
business and pleasure.
The graduated candles are chiefly notable as to their use, if not
invention, by Alfred the Great in about 883. They were 12 inches long,
divided into 12 parts, of which three would burn in one hour. In use
they were shielded from the wind by thin pieces of horn, and thus the
“horn lantern” originated. With them he divided the day into three equal
parts, one for religion, one for public affairs, and one for rest and
recreation.
Useful clocks of wondrous make were described in the annals of the
middle ages, especially in Germany, made by monks and others for Kings,
monasteries and churches. The old Saxon and Teutonic words _cligga_, and
_glocke_, signifying the striking of a bell, and from which the name
clock is derived, indicates the early combination of striking and
time-keeping mechanism. The records are scant as to the particulars of
inventions in horology during the middle ages and down to the sixteenth
century, but we know that weights, and trains of wheels and springs, and
some say pendulums, were used in clockwork, and that the tones of hourly
bells floated forth from the dim religious light of old cathedrals. They
all appear to have involved in different forms the principle of the old
clepsydra, using either weights or water as the motive power to drive a
set of wheels and to move a pointer over the face of a dial.
Henry de Vick of France about 1370 constructed a celebrated clock for
Charles V., the first nearest approach to modern weight clocks. The
weight was used to unwind a cord from a barrel. The barrel was connected
to a ratchet and there were combined therewith a train of toothed wheels
and pinions, an escapement consisting of a crown wheel controlled by two
pallets, which in turn were operated alternately by two weights on a
balanced rod. An hour hand was carried by a shaft of the great wheel,
and a dial plate divided into hours. This was a great advance, as a more
accurate division of time was had by improving the isochronous
properties of the vibrating escapement. But the world was still wanting
a time-keeper to record smaller portions of the day than the hour and a
more accurate machine than Vick’s.
Two hundred years, nearly, elapsed before the next important advance in
horology. By this time great astronomers like Tycho Brahe and Valherius
had divided the time-recording dials into minutes and seconds.
About 1525 Jacob Zech of Prague invented the fusee, which was
re-invented and improved by the celebrated Dr. Hooke, 125 years later.
Small portable clocks, the progenitors of the modern watch, commenced to
appear about 1500. It was then that Peter Hele of Nuremberg substituted
for weights as the motive power a ribbon of steel, which he wound around
a central spindle, connecting one end to a train of wheels to which it
gave motion as it unwound.
Then followed the famous observation of the swinging lamp by the then
young Galileo, about 1582, while lounging in the cathedral of Pisa. The
isochronism of the vibrations of the pendulum inferred from this
observation was not published or put to practical application in clocks
for nearly sixty years afterward. In 1639 Galileo, then old and blind,
dictated to his son one of his books in which he discussed the
isochronal properties of oscillating bodies, and their adaptation as
time measures. He and others had used the pendulum for dividing time,
but moved it by hand and counted its vibrations. But Huygens, the great
Dutch scientist, about 1556 was the first to explain the principles and
properties of the pendulum as a time measurer and to apply it most
successfully to clocks. His application of it was to the old clock of
Vick’s.
The seventeenth century thus opened up a new era in clock and watch
making. The investigations, discoveries, and inventions of Huygens and
other Dutch clock-makers, of Dr. Hooke and David Ramsey of England,
Hautefeuille of France, and a few others placed the art of clock and
watch making on the scientific basis on which it has ever since rested.
The pendulum and watch-springs needed to have their movements controlled
and balanced by better escapements. Huygens thought that the pendulum
should be long and swing in a cycloidal course, but Dr. Hooke found the
better way to produce perfect isochronous movements was to cause the
pendulum to swing in short arcs, which he accomplished by his invention
of the anchor escapement.
The fusee which Dr. Hooke re-invented consists of a conical
spirally-grooved pulley, around which a chain is wound, and which is
connected at one end to a barrel, in which the main actuating spring is
tightly coiled. The fusee is thus interposed between the wheel train and
the spring to equalise the power of the latter.
To Dr. Hooke must also be credited the invention of that delicate but
efficient device, the hair-spring balance for watches. His inventions in
this line were directed to the best means of utilising and controlling
the force of springs, his motto being “_ut tensio sic vis_,” (as the
tension is so is the force.) Repeating watches to strike the hours,
half-hours and quarters, made their appearance in the seventeenth
century. In the next century Arnold made one for George III., as small
as an English sixpence. This repeated the hours, halves and quarters,
and in it for the first time in the art a jewel was used as a bearing
for the arbors, and this particular one was a ruby made into a minute
cylinder.
After the discovery and practical application of weights, springs,
wheels, levers and escapements to time mechanisms, subsequent
inventions, numerous as they have been, have consisted chiefly, not in
the discovery of new principles, but in new methods in the application
of old ones. Prior to the eighteenth century, however, clocks were
cumbrous and expensive, and the watches rightly regarded as costly toys;
and as to their accuracy in time-measuring, the cheaper ones were hardly
as satisfactory as the ancient sun-dials.
With the coming of the machine inventions and the new industrial and
social ideas of the eighteenth century came an almost sudden new
appreciation of the value of time. Hours, minutes and seconds began to
be carefully prized, both by the trades and professions, and the demand
from the common people for accurate time records became great. This
demand it has been the office of the nineteenth century to supply, and
to place clocks and watches within the reach of the poor as well as the
rich. While thus lessening the cost of time-keepers their value has been
enhanced by increasing their accuracy and durability.
Among the other ideas for which the eighteenth century was famous in
watch-making was that of dispensing with the key for winding, thus
saving the losing of keys and preventing access of dust, an idea which,
however, was perfected only in the last half of the nineteenth century.
The eighteenth century was chiefly distinguished by its scientific
improvements in time-keepers, to adapt them for astronomical
observations and for use at sea, in not only accurately determining the
time, but the degrees of longitude. Chronometers were invented,
distinguished from watches and clocks, by means by which the fluctuation
of the parts caused by the variations in temperature are obviated or
compensated. In clocks what are known as the mercurial and gridiron
pendulums were invented respectively toward the close of the eighteenth
century by Graham and Harrison, and the latter also subsequently
invented the expanding and contracting balance wheel for watches. The
principle in these appliances is the employment of two different metals
which expand unequally, and thus maintain an uniformity of operation.
The Dutch, with Huygens in the lead, were long among the leading
clock-makers. Germany ranked next. It was in the seventeenth century
that a wonderful industry in clock-making there commenced, which lasted
for two centuries. The Black Forest region of South Germany became a
famous locality for the manufacture of cheap wooden clocks. The system
adopted was a minute division of labour. From fourteen to twenty
thousand hands twenty years ago were employed in the Schwarzwald
district. Labour-saving machines were ignored almost entirely. The
annual production finally reached nearly two million clocks, of the
value of about five million dollars.
Switzerland in watch-making followed precisely the example of Germany in
clock-making. It commenced there in the seventeenth and culminated in
the nineteenth century. Many thousands of its population were engaged in
the business and it flourished under the fostering care of the
government--by the establishment of astronomical observations for
testing the adjustment of the best watches, the giving of prizes, and
the establishment and encouragement of schools of horology conducted on
thorough scientific methods. A quarter of a century ago it was estimated
that in Switzerland 40,000 persons out of a population of 150,000 were
engaged in watch-making, and that the annual production sometimes
reached 1,600,000 completed movements. The whole world was their market.
The United States alone was in 1875 importing 134,000 watches annually
from that country.
As in Germany, so one characteristic of the Swiss system was a minute
sub-division of the labour. Individuals and entire families had certain
parts only to make. It is said that the Swiss watch passed through the
hands of one hundred and thirty different workmen before it was put upon
the market. The use of machines was also, as in Germany, ignored. By
this national devotion to a single trade and its sub-division of labour,
the successful production of complicated watches became great and their
prices comparatively low.
The United States in the commencement of its career and at the opening
of the century had no clocks or watches of its own manufacture. But it
soon followed the example of Germany and Switzerland and established
cheap clock manufactories, first of wood, and then of metal, which
became famous and of world-wide use. But it could make no headway
against the cheap labour of Europe in watch-making, and the country was
flooded with watches of all qualities, principally from Switzerland and
England. Finally, at the half-way mark in the century, the inquiry arose
among Americans, why could not the system of the minute sub-division of
human labour followed in watch-making countries so cheaply and
profitably, be accomplished by machinery? The field was open, the prize
was great, and the government stood ready to grant exclusive patents to
every inventor who would devise a new and useful machine. The problem
was great, as the fields abroad had been filled for generations by
skilled artisans who had reduced the complicated mechanism of
watch-making to a fine art. Fortunately the habit had been established
in America in several of the leading industries, principally in that of
fire-arms, of fabricating separate machinery for the independent making
of numerous parts of the same implement, whereby uniformity and
interchangeability were established. Under such a practice, which was
known as the American system, a duplicate of the smallest part of a
complicated machine, lost or worn out thousands of miles from the
factory, could soon be furnished by simply sending the number or name of
such required part to the manufacturer, or to the nearest dealer in such
machines.
With such encouragement and example the scheme of watch-making was
commenced. Soon large factories were built, and by the time of the
Centennial Exhibition in 1876, the American Watch Company of Waltham,
Massachusetts, were enabled to present an exhibit of watch movements
made by machinery, which astonished the world. Other great companies in
different parts of the country soon followed with the same general
system. Machines, working with the apparent intelligence and facility of
human minds and hands, and with greater mathematical accuracy than was
possible with the hands, appeared:--for cutting out the finest teeth
from blank wheels stamped out from steel or brass; for making and
cutting the smallest, finest threaded screws by the thousands per hour
and with greatest uniformity and accuracy; for jewel-making; for cutting
and polishing by diamonds, or sapphire-armed tools, the rough,
unpolished diamond and ruby, crysolite, garnet, or aqua-marine, and for
boring, finishing and setting the same; for the formation of the most
delicate pins or arbors; for the making of the escapements, including
forks, pallets, rollers, and scape wheels; for making springs and
balances, including the main-springs and hair-springs; for making and
setting the stem-winding parts; for making the cases, and engraving the
same, etc. The list would be too long to simply name all the ingenious
machines there exhibited and subsequently invented for every important
operation.
It was the aim of these manufacturers to locate every great factory in
some quiet and attractive spot, free from the dust of town, and city,
and divide it into many departments, from the blacksmithing to the
packing and transportation of the completed article; and to conduct
every department with the best mechanical and mathematical skill that
money and brains could provide.
The same system was followed with equal success in producing the
first-class pocket-chronometer for the nicest work to which chronometers
can be put.
Thus with every watch and its every part made the exact duplicate of its
fellow, uniformity in time-keeping has been established; and the simile
of Pope is no longer so correct, “’Tis with our judgments as our
watches, none go just alike, yet each believes his own.” A simple
statement of this system illustrates with greater force than an entire
volume the revolution the nineteenth century has produced in the useful
art of horology. And yet the story should not omit reference to the
application of the electric system to clocks, whereby clocks at distant
points of a city or country are connected, automatically corrected and
set to standard time from a central observatory or other time station.
Great as were the advances in horology during the seventeenth and
eighteenth centuries, the number of inventions that have been made in
the nineteenth century is evidenced by the fact that in the United
States alone about 4,000 patents have been granted since 1800, which,
however, represent not only American inventors but very many of other
countries.
_Registering Devices._--Devices for recording fares and money have
employed the keenest wits of many inventors and is an art of quite
recent origin. Attention was first directed to fare registers in public
vehicles, the object of which is to accurately report to the proper
office of the company at the end of a trip, or of the day, the number of
passengers carried and the fares received. Portable registers, to be
carried by the conductor and operated in front of the passenger have
been almost universally succeeded by stationary ones set up at one end
of the vehicle in open view of all the passengers and operated by a
strap and lever by the conductor. These fare registers have been called
“A mechanical conscience for street car conductors.”
_Cash Registers_, intended to compel honesty on the part of retail
salesmen, are required to be operated by them, and when the proper
lever, or levers, or it may be a crank handle, is or are touched, the
machine automatically records the amount of the sale, the amount of
change given, and the total amount of all the sales and money received
and paid out.
_Voting Machines_--designed to overcome the difficulties, expenditure of
time, and the commission of errors and frauds experienced in the reading
and counting of votes--have received great attention from inventors, and
are not yet in a satisfactory condition. The problem involves the
dispensing of printing the ballots, the prevention of fraudulent
deposition of ballots, the automatic correct counting of the same, and a
display of the result as soon as the balloting is closed.
Successful electrical devices have been made for recording the votes of
a great number of persons in a large assembly by the touch of an “aye”
or “nay” button at the seat of the voter and the recording of the same
on paper at a central desk.
The invention and extensive use of bicycles, automobiles, etc., have
given rise to the invention of _cyclometers_, which are small devices
connected to some part of the vehicle to indicate to the rider or driver
the rate at which he is riding, and the number of miles ridden.
_Speed Indicators._--Many municipalities having adopted ordinances
limiting the rate of speed for street and steam cars, bicycles,
automobiles, and other vehicles, a want was created, which has been met,
for devices to indicate to the passengers, drivers or conductors the
rate at which the vehicle is travelling, and to sound an alarm in case
of excess of speed, so that brakes can be applied and the speed reduced.
Or to relieve persons of anxiety and trouble in this respect, ingenious
devices have been contrived which automatically reduce the speed when
the prescribed limit has been exceeded.
_Weighing Scales and Machines._--“Just balances and just weights” have
been required from the day of the declaration, “a false weight is an
abomination unto the Lord.” And therefore strict accuracy must always be
the measure of merit of a weighing machine. To this standard the
inventions of the century in weighing scales have come. Until this
century the ordinary balance with equal even arms suspended from a
central point, and each carrying means for suspending articles to be
weighed, or compared in weights, and the later steelyard with its
unequal arms, with its graduated long arms and a sliding weight and
holding pan, were the principal forms of weighing machines. Platform
scales were described in an English patent to one Salman in 1796, but
their use is not recorded. The compound lever scale on the principle of
the steelyard, but arranged to be used with a platform, was invented and
came into use in the United States about 1831. Thaddeus and Erastus
Fairbanks of St. Johnsbury, Vermont, were the inventors, and it was
found to meet the want of farmers in weighing hemp, hay, etc., by more
convenient means than the ordinary steelyard. They converted the
steelyard into platform scales. The leading characteristics of such
machines are, first, a convenient platform nicely balanced on knife
edges of steel levers, and second, a graduated horizontal beam, a
sliding weight thereon connected by an upright rod at one end to the
beam, and at its opposite end to the balance frame beneath the platform.
The modification in size and adaptation of this machine for the weighing
of different commodities amounted to some 400 different
varieties--running from the delicately-constructed apparatus for
weighing the fraction of a grain, to the ponderous machines for weighing
and recording the loaded freight car of fifty or sixty tons, or the
canal-boat or other vessel with its load of five or six hundred tons.
The adaptation of a balance platform on which to place a light load, or
to drive thereon with heavy loads, whether of horses, steam, or water
vehicles, was a great blessing to mankind. No wonder that they were soon
sold all over the world, and that monarchs and people hastened to heap
honors on the inventors.
Spring weighing scales have recently been invented, which will
accurately and automatically show not only the weight but the total
price of the goods weighed, the price per unit being known and fixed.
In the weighing of large masses of coarse material, such as grain, coal,
cotton seed, and the like, machines have been constructed which
automatically weigh such materials and at the same time register the
weight.
Previous to this century no method was known, except the exercise of
good judgment in the light of experience, of accurately testing the
strength of materials. Wood and metals were used in unnecessarily
cumbrous forms for the purpose to which they were put, in order to
ensure safety, or else the strength of the parts failed where it was
most needed.
The idea of testing the tensile, transverse, and cubical resisting
strength of materials has been applied to many other objects than beams
and bars of wood and metals; to belts, cloths, cables, wires, fibres,
paper, twine, yarn, cement, and to liquids. Kiraldy, Kennedy, and others
of England, Thomasset of France, Riehle of Germany, and Fairbanks,
Thurston and Emery of the United States, are among the noted inventors
of such machines.
In the Emery system of machines, consisting of scales, gages, and
dynamometers, the power exerted on the material tested is transmitted
from the load to an indicating device by means of liquid acting on
diaphragms. The same principle is employed in his weighing machines.
By one of these hydraulic testing machines the tensile strength of
forged links has been ascertained by the exertion of a power amounting
to over 700,000 pounds before breaking a link, the chain breaking with a
loud report.
The most delicate materials are tested by the same machine--the tensile
strength of a horsehair, some of which are found to stand the strain of
one and two pounds. Eggs and nuts are cracked without being crushed, and
the power exerted and the strain endured automatically recorded. Steel
beams and rods have been subjected to a strain of a million pounds
before breaking.
Governments, municipalities, and the people generally are thus provided
with means by which they can proceed with the greatest confidence in the
safe and economical construction and completion of their buildings and
public works.