[1] An objection to this view is that according to the Augustan
historian Capitolinus (_Antoninus_, 2) Eutychius of Sicca was a Latin
not a Greek grammarian.
CYCLING, the clipped term now given comprehensively to the sport or
exercise of riding a bicycle (q.v.) or tricycle (q.v.).
History.
Suggestions of vehicles having two or more wheels and propelled by the
muscular effort of the rider or riders are to be found in very early
times, even on the bas-reliefs of Egypt and Babylon and the frescoes of
Pompeii; but though sporadic examples of such contrivances are recorded
in the 17th and 18th centuries, it was apparently not till the beginning
of the 19th century that they were used to any considerable extent. A
"velocipede" invented by Blanchard and Magurier, and described in the
_Journal de Paris_ on the 27th of July 1779, differed little from the
_celerifere_ proposed by another Frenchman, de Sivrac, in 1690; it
consisted of a wooden bar rigidly connecting two wheels placed one in
front of the other, and was propelled by the rider, seated astride the
bar, pushing against the ground with his feet. The next advance was made
in the _draisine_ of Freiherr Karl Drais von Sauerbronn (1785-1851),
described in his _Abbildung und Beschreibung seiner neu erfundenen
Laufmaschine_ (Nuremberg, 1817). In this the front wheel was pivoted on
the frame so that it could be turned sideways by a handle, thus serving
to steer the machine (figs. 1 and 2). A similar machine, the
"celeripede," also with a movable front wheel, is said to have been
ridden by J. N. Niepce in Paris some years before. In England the
draisine achieved a great, though temporary, vogue under various names,
such as velocipede, patent accelerator, bivector, bicipedes, pedestrian
curricle (patented by Dennis Johnson in 1818), dandy horse, hobby horse,
&c., and for a time it was popular in America also. The propulsion of
the draisine by pushing with the feet being alleged to give rise to
diseases of the legs, arrangements were soon suggested, as by Louis
Gompertz in England in 1821, by which the front wheel could be rotated
by the hands with the aid of a system of gearing, but the idea of
providing mechanical connexions between the feet and the wheels was
apparently not thought of till later. Pedals with connecting rods
working on the rear axle are said to have been applied to a tricycle in
1834 by Kirkpatrick McMillan, a Scottish blacksmith of Keir,
Dumfriesshire, and to a draisine by him in 1840, and by a Scottish
cooper, Gavin Dalzell, of Lesmahagow, Lanarkshire, about 1845. The
draisine thus fitted had wooden wheels, with iron tires, the leading one
about 30 in. in diameter and the driving one about 40 in., and thus it
formed the prototype, though not the ancestor, of the modern rear-driven
safety bicycle.
[Illustration: FIG. 1.--Gentleman's Hobby Horse.]
[Illustration: FIG. 2.--Lady's Hobby Horse.]
[Illustration: FIG. 3.--The Boneshaker, 1868.]
[Illustration: FIG. 4.--The "Phantom," 1869.]
For the next 20 years little was done, and then began the evolution of
the high "ordinary" bicycle with a large driving wheel in front and a
small trailing one behind. About 1865 Pierre Lallement in Paris
constructed a bicycle in which the front wheel was driven by pedals and
cranks attached directly to its axle, but it is doubtful whether the
origin of this idea must be attributed to him or to Ernest Michaux, the
son of his employer, who was a carriage repairer. Lallement took his
machine to the United States, and in 1866 was granted a patent which had
an important influence on the subsequent course of the cycle industry in
that country. This machine, consisting of a wooden frame supported on
two wooden wheels (fig. 3), soon became popular in England, as well as
in France and America, and came to be called bicycle (or bysicle) by
those who took it seriously and "boneshaker" by those who did not.
Improvements quickly followed, chiefly in England, for in America the
popularity of the machine was short-lived, and in France the industry
was checked by the Franco-German war. Rubber tires, in place of iron
ones, appeared in 1868, and in two or three years were made very large,
2 in. or more in width. Suspension wheels, with wire spokes in tension,
were seen at the Crystal Palace, London, on the "Phantom" (fig. 4) of W.
F. Reynolds and J. A. Mays in 1869, and early in the same year the
manufacture of bicycles, at first for export to France, was begun in
England by the Coventry Sewing Machine Company, till then makers of
sewing machines. There was a rapid growth in the size of the front
wheel, which in the boneshaker normally measured 36 or 38 in. in
diameter, with a corresponding shrinkage in the rear wheel (fig. 5),
until by 1874, the date of the invention of the tangent wheel by J. K.
Starley 54-in. wheels were being made. The high bicycle was now fairly
established in form, and the changes made in the subsequent 10 or 15
years during which it retained its supremacy were chiefly in the
details of construction, such as the adoption of steel tubing for the
frames, the use of hollow rims in the wheels and the application first
of cone and then of ball bearings to points of friction. The weight of a
54-in. bicycle, which in 1874-1875 exceeded 50 or even 60 lb., was thus
reduced to well under 40 lb. in machines intended for use on ordinary
roads, and to not much over 20 lb. in the case of racers.
[Illustration: FIG. 5.--Humber's "Spider," 1872.]
[Illustration: FIG. 6.--Rudge Racing Ordinary, 1887.]
The high "ordinary" bicycle (fig. 6) gave unquestionable pleasure to
many riders, and very fast times were made with it both on the road and
on the racing path. In 1882 H. L. Cortis rode 20 m. 300 yds. in one
hour, and in April 1884 Thomas Stevens started from San Francisco to
ride round the world, a feat which he accomplished in December 1886. But
it had various disadvantages. The vibration set up by the small back
wheel was very trying, and in spite of the size of the front one the
rider had to move his pedals at an uncomfortably rapid rate if he wished
to maintain a good speed. Moreover his seat was placed in such a
position that he was liable to be pitched over the handlebar if his
wheel encountered a comparatively small obstacle. Attempts were made to
remedy these inconveniences in various ways. From the early 'eighties
much attention was devoted to tricycles, and these were produced in
innumerable designs, whether for a single rider, or for two in the form
of "sociables," in which the riders sat side by side, or of "tandems,"
in which one sat behind the other. But their weight, and consequently
the exertion of propelling them, was necessarily greater than in the
case of the bicycle, and by the end of the decade, the demand for them
had fallen off, though they are still made to a certain extent, chiefly
for carrying purposes. The two-track dicycle (fig. 7), invented by E. C.
F. Otto about 1879, in which the rider balanced himself between two
equal wheels placed abreast, also failed to secure lasting success.
[Illustration: FIG. 7.--Otto Dicycle, 1879.]
The improvement of the high bicycle was attempted in two directions. On
the one hand it was modified by placing the rider farther back, his
position "over his work" being ensured by arranging the pedals
immediately below him and connecting them to the front wheel, which was
usually reduced in size, by levers and cranks or by chain-gearing, often
with a multiplying action. On the other, the rear wheel was enlarged and
made the driving wheel. The "'Xtraordinary" (fig. 8), "Facile" (fig. 9)
and "Kangaroo" were examples of the former kind, which were often spoken
of as "dwarf-safeties"; but though a good many of them were used about
1880 and following years, both they and the "ordinary" bicycle
ultimately disappeared before machines of the second kind, which
developed into the modern rear-driven safety. There are numerous
claimants for the invention--or rather the reinvention--of this type,
but it appears that the credit for its practical and commercial
introduction in substantially its present form is due to J. K. Starley
in England. His "Rover" (fig. 10), brought out late in 1885, had two
nearly equal wheels, the driving wheel 30 in. in diameter and the
steering 32 in., and the rider sat so far back that he could not be
thrown forward over the handles. The motion imparted by the pedals to a
sprocket wheel mounted between the wheels was transmitted by an endless
chain to the rear wheel, and by sufficiently increasing the size of this
sprocket wheel the machine could be made to travel as far or farther
than the "ordinary" for each complete revolution of the pedals. From
about 1890 the "safety" monopolized the field. At first it was fitted
with the narrow rubber tires customary at the time, but these gave way
to pneumatic tires, invented in 1888 by J. B. Dunlop, a veterinary
surgeon of Belfast, whose idea, however, had been anticipated in the
English patent taken out by R. W. Thomson in 1845. The result was a
great gain in comfort, due to reduction of vibration, and a remarkable
increase of speed or, alternatively, decrease of exertion. Subsequent
progress was mainly in the details of design and manufacture, tending to
secure lightness combined with adequate strength, and such was the
success attained, by the application of scientific principles and of
improved methods and materials to the construction of the frames and
other parts, that while the weight of the original "Rover" was about 50
lb. that of its successors 20 years later with 28-in. wheels was reduced
by 35 or 45%, or even 60% in the case of racing machines. The beginning
of the 20th century saw the introduction of two innovations: one was the
"free-wheel," a device which allows the driving wheel to rotate
independently of the chain and pedals, so that the rider, controlling
his speed with powerful brakes, can "coast" down a hill using the
stationary pedals as foot-rests; and the other was the motor-cycle, in
which a petrol-engine relieves him, except at starting, from all
personal exertion, though at the cost of considerable vibration. A third
contrivance, which, however, was an idea of considerably older date,
also began to find favour about the same period in the shape of
two-speed and three-speed gears, enabling the rider at will to alter the
ratio between the speed of revolution of his pedals and of his driving
wheel, and thereby accommodate himself to the varying gradients of the
road he is traversing (see also BICYCLE, TRICYCLE and TIRE).
[Illustration: FIG. 8.--Singers' "'Xtraordinary," 1879.]
[Illustration: FIG. 9.--The "Facile," 1879.]
[Illustration: FIG. 10.--Starley's "Rover," 1885.]
The safety bicycle, with pneumatic tires, rendered cycling universally
popular, not merely as a pastime but as a convenient means of locomotion
for everyday use. Made with a drop-frame, it also enabled women to cycle
without being confined to a heavy tricycle or compelled to assume
"rational dress." In consequence there was an enormous expansion in the
cycle industry. In England the demand for machines had become so great
by 1895 that the makers were unable to cope with it. Numbers of new
factories were started, small shops grew into large companies, and the
capital invested advanced by millions of pounds. The makers who had
devoted their mechanical skill to perfecting the methods of
cycle-construction were swallowed up by company promoters and
adventurers, bent simply upon filling their own pockets. The march of
mechanical invention and improvement was arrested, and machines, instead
of being built by mechanics proud of their work, in many cases were
merely put together in the shortest possible time and in a few standard
patterns. For these the world clamoured, and for a year they could not
be produced fast enough. Then the demand fell off, the British market
became over-stocked, and as the British makers declined to consider the
wants of foreign customers, their store-rooms remained crowded with
machines that could not be sold. Speculative finance, such as was
exemplified in 1896 by the flotation for L5,000,000 of the Dunlop tire
company, which had been started in 1889 with a capital of L25,000, had
its natural effects. There ensued widespread and continuing
disorganization of the trade, which had to be met by extensive
reconstructions of over-capitalized companies. English makers too had
lost the commanding international position they once enjoyed, when they
supplied almost the entire demand for bicycles in many parts of the
world, including the United States. In America the manufacture of
bicycles was not begun until about 1878, when it was introduced by A. A.
Pope (1843-1909), and even by 1890 the value of the products barely
exceeded 2(1/2) million dollars, while for several years later much of the
steel tubing required for bicycle manufacture continued to be imported
from Great Britain. The industry, however, thanks to automatic machinery
and perfect organization, grew rapidly, and in 1900 the value of its
products was nearly 32 million dollars. In the two years 1897 and 1898
the exports of cycles and cycle parts alone were worth nearly 14 million
dollars, though they fell off in subsequent years, and English makers
had to contend with an American invasion in addition to their domestic
troubles. But the competition was short-lived. The American makers sent
over machines with single tube tires and wooden rims which did not
secure the approval of the British purchaser, and so they too lost their
hold. In the opening years of the 20th century the industry in Great
Britain gradually recovered itself. More attention was paid to the
production of cheap machines which were sound and trustworthy, and sales
were further stimulated by the introduction of systems of deferred
payments. In 1905 about 600,000 machines were made in Great Britain, and
47,604 were exported, the total value of the home-market for cycles and
their parts being about 3(1/2) millions sterling, and of the export trade
about one million. In the same year the number of machines imported was
only 2345.
Touring clubs.
Cycle tours were taken and cycle clubs established almost as soon as the
cycle appeared, the Pickwick Bicycle Club in London, founded in 1870,
being the oldest in the world. The organization of these clubs is
chiefly of a social character, and a few possess well-appointed
club-houses. To a great extent they have been superseded by the large
touring organizations. The Cyclists' Touring Club, organized in 1878 as
the Bicycle Touring Club, has members scattered through Europe, America
and even the East. Many other countries possess national clubs, as for
instance the League of American Wheelmen, founded in 1880, and the
Touring Club de France, founded in 1895, of whose objects cycling is
only one, though the chief. The aim of these national associations,
which have formed an international touring league, is the promotion of
cycle touring. To this end they publish roadbooks, maps and journals;
they recommend hotels, with fixed tariffs, in their own and other
countries; they appoint representatives to aid their members when
touring; and they have succeeded in inducing most governments to allow
their members to travel freely across frontiers without paying duty on
their machines. In all countries they have erected warning-boards at
dangerous places; in France the best route is suggested by a sign-post,
and cyclists who meet with accidents in lonely places find repair
outfits provided for their free use. Another important part of the work
of these clubs, either directly or indirectly, is the improvement of the
roads. France has done more for the cyclist than any other country,
owing to the fact that she possesses the best roads, kept up to a
certain extent by the cycle tax, whereby the cyclist acquires a certain
official position and right; moreover cycles accompanied by their owners
are conveyed without extra charge on the railways, and aid is given to
the sport and pastime from public funds. In Belgium the cycle has worked
a veritable revolution in the national life. The surface of the greater
part of the country being loose and sandy, the roads have been paved,
and this paving is so bad as to be impossible for light traffic. The
cycle tax has consequently been devoted, first, to the construction of
paths on which cyclists have equal rights with pedestrians, and secondly
to the replacing of the paving by macadam. In this way alone cycling has
proved of inestimable benefit to Belgium and Luxembourg. In the United
States measures for securing good roads and side paths have been
introduced in various states, mainly at the instigation first of
cyclists and then of motorists, and in Great Britain the Roads
Improvement Association has worked for the same end.
Racing.
Each country also possesses an organization for the government of cycle
racing; and although these unions, one object of which--usually the main
one--is the encouragement of cycle racing and cycle legislation, boast
an enormous membership, their membership is often composed of clubs and
not individuals. Among the most important are the National Cyclists'
Union of England and the Union Velocipedique of France. These bodies are
also bound together by the International Cyclists' Association, which is
devoted mainly to the promotion of racing and legislation connected with
it all over the world. The National Cyclists' Union, originally the
Bicycle Union, which was the parent body of all, formed in February
1878, was the first to put up danger-boards, and also was early
instrumental, alone and with the C.T.C., in framing or suggesting laws
for the proper government and regulation of cycle traffic, notably in
establishing its position as a vehicle in securing universal rights, in
endeavouring, again in conjunction with the C.T.C., to increase
facilities for the carriage of cycles on the railways, in securing the
opening of parks, and in promoting many other equally praiseworthy
objects. For a number of years, however, it has been more prominent as
the ruling race-governing body. But cycle racing has fallen upon evil
days. At one time cycle racing attracted a large number of spectators,
but gradually it lost the public favour, or rather was ignored by the
public because it became mainly an advertisement for cycle makers. The
presence of the man, directly or indirectly, in the employ of, or aided
by a maker, and the consequent mixing up of trade and sport, lowered
racing not only in the public estimation, but in that of all genuine
amateurs. There have always been a few amateurs who have raced for the
love of the sport, but the greater number of prominent racing men have
raced for the benefit of a firm, so much so that, at one time, an entire
section of racing men were classed as "makers' amateurs." They did not
confine themselves to the race track, but appropriated the public roads
until they became a danger and a nuisance, and road-racing finally was
abolished, though record rides, as they are called, are still indulged
in, being winked at by the police and by the cycling authorities. The
makers' amateurs at least rode to win and to make the best time
possible. But the scandal was so great that a system of licensing riders
was adopted by the N.C.U., and if this did not effectively kill the
sport, the introduction of waiting races did. There probably is
considerable skill in riding two-thirds of a race as slowly as possible,
and only hurrying the last part of the last lap, but it does not amuse
the public, who want to see a fast race as well as a close finish. The
introduction of pacing by multicycles and motors next took from cycle
racing what interest was left. A motor race, in which the machines are
run at top speed, is more exciting than the spectacle of a motor being
driven at a rate which the cyclist can follow with the protection of a
wind-shield. In America this system of proving what cyclists can do with
racing machines was carried so far that in 1899 a board track was laid
down on the Long Island railway for about 2 m. between the metals, and a
cyclist named Murphy, followed a train, and protected by enormous
wind-shields, succeeded in covering a mile in less than a minute in the
autumn of 1900. Other cyclists have devoted themselves, at the
instigation of makers, to the riding of 100 m. a day every day for a
year. It would be difficult to say what advantage there is in these
trials and contests. They are not convincing records, and only prove
that some people are willing to take great personal risks for the
benefit of their employers. E. Hale, during 1899-1900, covered 32,496 m.
in 313 days. For many years also long-distance races, mostly of six
days' duration, have been promoted on covered tracks, and though
condemned by all cycling organizations, they find a great deal of
pecuniary support.
Military.
The cycle has also been taken up for military purposes. For this idea
the British army is indebted to Colonel A. R. Savile, who in 1887
organized the first series of cycle manoevres in England. Since then
military cycling has undergone a great development, not only in the
country of its origin but in most others.
Literature.
Cycling has produced a literature of its own, both of the pastime and
of the trade. Owing to the enormous profits which, for several years,
were obtained by cycle makers, a trade press appeared which simply
lived by, and out of, its advertisers; and though each country has one
or more genuine trade journals, the large proportion of these sheets
have been worth, in a business aspect, as little practically as from a
literary standpoint. On the other hand a vast mass of practical and
unpractical, scientific and medical, historical and touring treatises
and records have appeared, but mostly of a rather ephemeral character.
CYCLOID (from Gr. [Greek: kuklos], circle, and [Greek: eidos], form), in
geometry, the curve traced out by a point carried on a circle which
rolls along a straight line. The name cycloid is now restricted to the
curve described when the tracing-point is on the circumference of the
circle; if the point is either within or without the circle the curves
are generally termed _trochoids_, but they are also known as the
_prolate_ and _curtate_ cycloids respectively. The cycloid is the
simplest member of the class of curves known as roulettes.
No mention of the cycloid has been found in writings prior to the 15th
century. Francis Schooten (_Commentary on Descartes_) assigns the
invention of the curve to Rene Descartes and the first publication on
this subject after Descartes to Marin Mersenne. Evangelista Torricelli,
in the first regular dissertation on the cycloid (_De dimensione
cycloidis_, an appendix to his _De dimensione parabolae_, 1644), states
that his friend and tutor Galileo discovered the curve about 1599. John
Wallis discussed both the history and properties of the curve in a tract
_De cycloide_ published at Oxford in 1659. He there shows that the
cycloid was investigated by Carolus Bovillus about 1500, and by Cardinal
Cusanus (Nicolaus de Cusa) as early as 1451. Honore Fabri (_Synopsis
geometrica_, 1669) treated of the curve and enumerated many theorems
concerning it. Many other mathematicians have written on the
cycloid--Blaise Pascal, W. G. Leibnitz, the Bernoullis, Roger Cotes and
others--and so assiduously was it studied that it was sometimes named
the "Helen of Geometers." The determination of the area was the subject
of many investigations and much controversy. Galileo attempted the
evaluation by weighing the curve against the generating circle; this
rough method gave only an approximate value, viz., a little less than
thrice the generating circle. Torricelli, by employing the "method of
indivisibles," deduced that the area was exactly three times that of the
generating circle; this result had been previously established in 1640
in France by G. P. de Roberval, but his investigation was unknown in
Italy. Blaise Pascal determined the area of the section made by any line
parallel to the base and the volumes and centres of gravity of the
solids generated by revolving the curve about its axis and base. Before
publishing his results he proposed these problems for public competition
in 1658 under the assumed name of Amos Dettonville. John Wallis in
England, and A. la Louere in France, accepted the challenge, but the
former could only submit incorrect solutions, while the latter failed
completely. Having established his priority, Pascal published his
investigations, which occasioned a great sensation among his
contemporaries, and Wallis was enabled to correct his methods. Sir
Christopher Wren, the famous architect, determined the length of the arc
and its centre of gravity, and Pierre Fermat deduced the surface of the
spindle generated by its revolution. A famous period in the history of
the cycloid is marked by a bitter controversy which sprang up between
Descartes and Roberval. The evaluation of the area of the curve had made
Roberval famous in France, but Descartes considered that the value of
his investigation had been grossly exaggerated; he declared the problem
to be of an elementary nature and submitted a short and simple solution.
At the same time he challenged Roberval and Fermat to construct the
tangent; Roberval failed but Fermat succeeded. This problem was solved
independently by Vicenzo Viviani in Italy. The cartesian equation was
first given by Wilhelm Gottfried Leibnitz (_Acta eruditorum_, 1686) in
the form y = (2x - x^2)(1/2) + [int](2x - x^2)(1/2)dx. Among other early
writers on the cycloid were Phillippe de Lahire (1640-1718) and Francois
Nicole (1683-1758).
The mechanical properties of the cycloid were investigated by Christiaan
Huygens, who proved the curve to be tautochronous. His enquiries into
evolutes enabled him to prove that the evolute of a cycloid was an equal
cycloid, and by utilizing this property he constructed the isochronal
pendulum generally known as the _cycloidal pendulum_. In 1697 John
Bernoulli proposed the famous problem of the _brachistochrone_ (see
MECHANICS), and it was proved by Leibnitz, Newton and several others
that the cycloid was the required curve.
The method by which the cycloid is generated shows that it consists of
an infinite number of cusps placed along the fixed line and separated
by a constant distance equal to the circumference of the rolling
circle. The name cycloid is usually restricted to the portion between
two consecutive cusps (fig. 1, curve a); the fixed line LM is termed
the base, and the line PQ which divides the curve symmetrically is the
_axis_. The co-ordinates of any point R on the cycloid are expressible
in the form x = a([theta] + sin [theta]); y = a(1 - cos [theta]),
where the co-ordinate axes are the tangent at the vertex O and the
axis of the curve, a is the radius of the generating circle, and
[theta] the angle R'CO, where RR' is parallel to LM and C is the
centre of the circle in its symmetric position. Eliminating [theta]
between these two relations the equation is obtained in the form x =
(2ay - y^2)(1/2) + a vers-^1 y/a. The clumsiness of the relation
renders it practically useless, and the two separate relations in
terms of a single parameter [theta] suffice for the deduction of most
of the properties of the curve. The length of any arc may be
determined by geometrical considerations or by the methods of the
integral calculus. When measured from the vertex the results may be
expressed in the forms s = 4a sin 1/2[theta] and s = [root](8ay); the
total length of the curve is 8a. The intrinsic equation is s = 4a sin
[psi], and the equation to the evolute is s = 4a cos [psi], which
proves the evolute to be a similar cycloid placed as in fig. 2, in
which the curve QOP is the evolute and QPR the original cycloid. The
radius of curvature at any point is readily deduced from the intrinsic
equation and has the value [rho] = 4 cos 1/2[theta], and is equal to
twice the normal which is 2a cos 1/2[theta].
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
[Illustration: FIG. 3.]
The _trochoids_ were studied by Torricelli and F. van Schooten, and
more completely by John Wallis, who showed that they possessed
properties similar to those of the common cycloid. The cartesian
equation in terms similar to those used above is x = a[theta] + b sin
[theta]; y = a - b cos [theta], where a is the radius of the
generating circle and b the distance of the carried point from the
centre of the circle. If the point is without the circle, i.e. if a <
b, then the curve exhibits a succession of nodes or loops (fig. 1,
curve b); if within the circle, i.e. if a > b, the curve has the form
shown in fig. 1, curve c.
The _companion to the cycloid_ is a curve so named on account of its
similarity of construction, form and equation to the common cycloid.
It is generated as follows: Let ABC be a circle having AB for a
diameter. Draw any line DE perpendicular to AB and meeting the circle
in E, and take a point P on DE such that the line DP = arc BE; then
the locus of P is the companion to the cycloid. The curve is shown in
fig. 3. The cartesian equation, referred to the fixed diameter and the
tangent at B as axes may be expressed in the forms x = a[theta], y =
a(1 - cos [theta]) and y - a = a sin (x/a - 1/2[pi]); the latter form
shows that the locus is the harmonic curve.
For epi- and hypo-cycloids and epi- and hypo-trochoids see EPICYCLOID.
REFERENCES.--Geometrical constructions relating to the curves above
described are to be found in T. H. Eagles, _Constructive Geometry of
Plane Curves_. For the mechanical and analytical investigation,
reference may be made to articles MECHANICS and INFINITESIMAL
CALCULUS. A historical bibliography of these curves is given in
Brocard, _Notes de bibliographie des courbes geometriques_ (1897). See
also Moritz Cantor, _Geschichte der Mathematik_ (1894-1901).
CYCLOMETER (Gr. [Greek: kyklos], circle, and [Greek: metron], measure),
an instrument used especially by cyclists to determine the distance they
have traversed. In a common form a stud attached to one spoke of the
wheel engages with a toothed pinion and moves it on one tooth at each
revolution. The pinion is connected with a train of clockwork, the
gearing of which bears such a ratio to the circumference of the wheel
that the distance corresponding to the number of times it has revolved
is shown on a dial in miles or other units.
CYCLONE (Gr. [Greek: kyklon], whirling, from [Greek: kyklos], a circle),
an atmospheric system where the pressure is lowest at the centre. The
winds in consequence tend to blow towards the centre, but being diverted
according to Ferrel's law they rotate spirally inwards at the surface of
the earth in a direction contrary to the movement of the hands of a
watch in the northern hemisphere, and the reverse in the southern
hemisphere. The whole system has a motion of translation, being usually
carried forward with the great wind-drifts like eddies upon a swift
stream. Thus their direction of movement over the British Islands is
usually from S.W. to N.E., though they may remain stationary or move in
other directions. The strength of the winds depends upon the atmospheric
gradients. (See METEOROLOGY.)
CYCLOPEAN MASONRY (from the Cyclopes, the supposed builders of the walls
of Mycenae), a term in architecture, used, in conjunction with Pelasgic,
to define the rude polygonal construction employed by the Greeks and the
Etruscans in the walls of their cities. In the earliest examples they
consist only of huge masses of rock, of irregular shape, piled one on
the other and trusting to their great size and weight for cohesion;
sometimes smaller pieces of rock filled up the interstices. The walls
and gates of Tiryns and Mycenae were thus constructed. Later, these
blocks were rudely shaped to fit one another. It is not always possible
to decide the period by the type of construction, as this depended on
the material; where stratified rocks could be obtained, horizontal
coursing might be adopted; in fact, there are instances in Greece, where
a later wall of cyclopean construction has been built over one with
horizontal courses.
CYCLOPES ([Greek: Kyklopes], the round-eyed, plural of Cyclops), a type
of beings variously described in Greek mythology. In Homer they are
gigantic cave-dwellers, cannibals having only one eye, living a pastoral
life in the far west (Sicily), ignorant of law and order, fearing
neither gods nor men. The most prominent among them was Polyphemus. In
Hesiod (_Theogony_, 264) they are the three sons of Uranus and
Gaea--Brontes, Steropes and Arges,--storm-gods belonging to the family
of the Titans, who furnished Zeus with thunder and lightning out of
gratitude for his having released them from Tartarus. They were slain by
Apollo for having forged the thunderbolt with which Zeus slew Asclepius.
Later legend transferred their abode to Mt Aetna, the Lipari islands or
Lemnos, where they assisted Hephaestus at his forge. A third class of
Cyclopes are the builders of the so-called "Cyclopean" walls of Mycenae
and Tiryns, giants with arms in their belly, who were said to have been
brought by Proetus from Lycia to Argos, his original home (Pausanias ii.
16. 5; 25. 8). Like the Curetes and Telchines they are mythical types of
prehistoric workmen and architects, and as such the objects of worship.
The standard work on these and similar mythological characters is M.
Mayer, _Die Giganten und Titanen_ (1887); see also A. Boltz, _Die
Kyklopen_ (1885), who endeavours to show that they were an historical
people; W. Mannhardt, _Wald- und Feldkulte_ (1904); J. E. Harrison,
_Myths of the Odyssey_ (1882); and article in Roscher's _Lexikon der
Mythologie_ (bibliography).
CYCLOSTOMATA, or MARSIPOBRANCHII, a group of fishes including the
ordinary lampreys and hagfish, and so called from the wide permanently
gaping mouth which is without the hinged jaws characteristic of other
vertebrates (GNATHOSTOMATA). The class Cyclostomata consists of two
orders, the Myxinoids (or Hyperotreti) and the Petromyzontes (or
Hyperoartii), which, while showing sufficient resemblance in structure
to warrant their inclusion in the same class, are yet marked off by such
deep-seated differences as to indicate that they commenced to diverge
from one another far back in evolutionary time. The order Myxinoids
includes the hagfish (_Myxine_), common off the eastern, and occurring
also, though less commonly, off the western coasts of the north
Atlantic, and the genus _Bdellostoma_ (also known as _Homea_,
_Eptatretus_, in part--_Polistotrema_), including the "borers" of the
western American coast, New Zealand and the Cape of Good Hope. The order
Petromyzontes includes the widely distributed lampreys. The original
genus _Petromyzon_ (which it is now customary to subdivide into a number
of genera) includes the large sea lamprey (_P. marinus_) of the north
Atlantic coasts and the two fresh-water lampreys of European streams
(_P. fluviatilis_ and _P. planeri_, the latter of which is possibly only
a small-sized variety of the former species). In North America nine or
ten species of lampreys are known to occur, descriptions of which are
given by Jordan and Evermann (1). In the southern hemisphere occur the
two genera Mordacia (Chile, Tasmania) and _Geotria_ (Chile, Australia,
New Zealand) (2).
The Cyclostomes are remarkable among vertebrates in that they are
semiparasitic in habit. The lampreys--except some of the small
fresh-water forms--attach themselves to other fishes by their suctorial
mouth and proceed to rasp off the flesh by means of the horny teeth
carried by the highly-developed tongue. The Myxinoids have gone a step
further and actually bore their way right into the body of their prey,
devouring all the soft parts and leaving the skin behind as a mere
shell, empty but for the bones. Where the hagfish or borers are
abundant, as in certain localities off the east coast of Scotland and
off the west coast of California, they may do great damage to fisheries
from their habit of attacking fishes which are in difficulties through
being caught by a hook or in a net; the fish when drawn up being
frequently completely deprived of their flesh.
The Myxinoids retain the ancestral marine habitat, but the lampreys have
sought refuge from the struggle for existence by taking to fresh water
to a less or greater extent. Such a form as _Petromyzon marinus_ or
_Entosphenus tridentatus_ of the west coast of America is what is known
as anadromous in habit, i.e. it takes refuge in fresh water during the
breeding season, ascending rivers like the salmon for the purpose of
spawning. Certain species of lampreys, on the other hand, have
completely deserted the sea and spend their whole lives in fresh-water
streams or lakes. The lake lampreys show a reminiscence of their
ancestral migratory habits in leaving lakes and ascending streams in
order to deposit their spawn.
_Anatomy._--In structural features, the Cyclostomes show a curious
mixture of features which must be looked on as primitive with others
which are indicative of high specialization for their peculiar mode of
life. In general appearance they are "eel-like": they are elongated in
shape and adapted for swimming in eel fashion, i.e. the body is
propelled forward by the backward passage along it of waves of lateral
flexure. There are, however, certain conspicuous differences which at
once serve to distinguish a Cyclostome from any other fishes of eel-like
shape:--(1) the circular permanently open mouth, (2) the absence of all
trace of paired limbs, (3) the absence of paired external nasal
openings, and (4) the presence on the roof or at the tip of the head of
a conspicuous median opening--the pituitary opening.
It will be convenient, in describing the structural features of the
group, to take as a basis for the description the marine lamprey,
_Petromyzon marinus_. A marine lamprey is an eel-like creature 70 to
75 cm. in length. At the anterior end and situated somewhat ventrally
is the circular widely gaping mouth or buccal cavity, its lining
studded with sharply pointed thorn-like "teeth" and its edge fringed
with numerous sensory papillae. On the dorsal side of the head is the
conspicuous circular pituitary opening with prominent lips, while on
the sides are seen the eyes, and behind these a row of somewhat
rounded branchial openings or gill-clefts. At about the beginning of
the posterior fourth of the body, and in the midventral line, is the
anal opening, and immediately behind it is the prominent papilla
carrying the opening of the urogenital sinus. The hinder portion of
the body, in accordance with its function in locomotion, is flattened
from side to side, while its surface is increased by the development
of a median fin fold, divided, except in early stages of development,
into three portions, known as the first and second dorsal fins and the
caudal fin. The last mentioned is of the primitive protocercal type.
The whole surface of the body--which shows a conspicuous dark
marbling, especially dorsally, on a light ground--is covered with
highly glandular epidermis. An important feature is the complete
absence of all trace of the calcified placoid plates which are so
characteristic of the Elasmobranchii.
The Myxinoids differ from the lampreys in regard to several of the
above-mentioned characters. The edges of the mouth carry tentacle-like
barbels. The pituitary opening is close to the anterior edge of the
mouth opening instead of being right up on the dorsal side of the
head. The eyes are invisible, being greatly reduced and sunk far below
the surface, and in _Myxine_, though not in _Bdellostoma_, the row of
gill openings is represented by a single opening on each side nearly
in the midventral line and situated at about the end of the first
quarter of the body length. Ventrally the Myxinoid possesses on each
side of the body a row of remarkable epidermal glands which can
produce at will enormous quantities of glutinous slime. This
secretion, which, no doubt, is of much value as a protection from
attack, is composed of very fine threads, formed by the conversion of
the protoplasm of certain cells of the epidermal glands ("thread
cells") into an extremely fine, tightly coiled filament, which becomes
unwound when discharged to the exterior.
[Illustration: From D. Starr Jordan, _A Guide to the Study of Fishes_,
by permission of A. Constable & Co., Ltd.