The term _Horologia_ occurs very early in different parts of Europe;
but as this word, in old times, signified dials as well as clocks,
nothing decisive can be inferred from it, unless it can be shown by
concomitant circumstances or expressions, that it relates to a clock
rather than a dial. Dante seems to be the first author who hath
introduced the mention of an _orologio_ that struck the hour, and which
consequently cannot be a dial, in the following lines:--
Indi come horologio che _ne chiami_,
Nel hora che la sposa d’Idio surge,
Amattinar lo sposo, perche l’ami[1090].
Dante was born in 1265, and died in 1321, aged fifty-seven;
striking-clocks therefore could not have been very uncommon in Italy,
at the latter end of the thirteenth century or the beginning of the
fourteenth.
But the use of clocks was not confined to Italy at this period; for we
had an artist in England about the same time, who furnished the famous
clock-house near Westminster Hall, with a clock to be heard by the
courts of law, out of a fine imposed on the Chief Justice of the King’s
Bench, in the sixteenth year of Edward I., or in 1288[1091]. Blackstone
in his Commentaries has observed, that this punishment of Radulphus de
Hengham is first taken notice of in the Year Book[1092], during the
reign of Richard III., where indeed no mention is made of a clock being
thus paid for; but if the circumstances stated in the report of this
case are considered, it was highly unnecessary, and perhaps improper,
to have alluded to this application of the Chief Justice’s fine.
It appears by the Year Book, that Richard III. had closeted the
judges in the _Inner_ Star Chamber, to take their opinions upon three
points of law; the second of which was, “Whether a justice of the
peace, who had enrolled an indictment, which had been negatived by
the grand-jury, amongst the _true bills_, might be punished for this
abuse of his office.” On this question a diversity of opinion arose
amongst the judges, some of whom supposed that a magistrate could not
be prosecuted for what he might have done, whilst others contended
that he might, and cited the case of Hengham, who was fined eight
hundred marks for making an alteration in a record, by which a poor
defendant was to pay only six shillings and eightpence, instead of
thirteen shillings and fourpence. Thus far the answer of the judges to
the question was strictly proper; but the application of the fine to
build a clock-house was not the least material[1093]; besides, that it
was probably a most notorious fact to every student, upon his first
attending Westminster-hall, as we find judge Southcote, so much later,
in the early part of queen Elizabeth’s reign, not only mentioning
the tradition, but that the clock still continued there, which had
been furnished out of the Chief Justice’s fine[1094]. Sir Edward Coke
likewise adds, that the eight hundred marks were actually entered
on the roll, so that it is highly probable he had himself seen the
record[1095].
But we have remaining to this day some degree of evidence, not only
of the existence of such a clock, but that it is of the antiquity
already ascribed to it, viz. the reign of Edward I. On the side of New
Palace-yard, which is opposite to Westminster-hall, and in the second
pediment of the new buildings from the Thames, a dial is inserted
with this remarkable motto upon it, “_Discite justitiam moniti_,”
which seems most clearly to relate to the fine imposed on Radulphus
de Hengham being applied to the paying for a clock. But it may be
said that this inscription is on a dial and not upon a clock; which
though it appears upon the first stating it to be a most material
objection, yet I conceive it may receive the following satisfactory
answer. The original clock of Edward the First’s reign was probably a
very indifferent one, but from its great antiquity, and the tradition
attending it, was still permitted to remain till the time of queen
Elizabeth, according to the authorities already cited. After this,
being quite decayed, a dial might have been substituted and placed
upon the same clock-house, borrowing its very singular motto; which
whether originally applied in the time of Edward I. or in later reigns,
most plainly alludes to Hengham’s punishment for altering a record.
It should also be mentioned that this dial seems to have been placed
exactly where the clock-house stood according to Strype[1096].
Mr. Norris, secretary to the Society of Antiquaries, hath been likewise
so obliging as to refer me to the following instance of a very ancient
clock in the same century: _Anno 1292, novum orologium magnum in
ecclesia_ (Cantuariensi), _pretium 30l._[1097].
I shall now produce a proof, that not only clocks but watches were made
in the beginning of the fourteenth century. Seven or eight years ago,
some labourers were employed at Bruce Castle, in Fifeshire, where they
found a watch, together with some coin, both of which they disposed
of to a shopkeeper of St. Andrews, who sent the watch to his brother
in London, considering it as a curious piece of antiquity. The outer
case is silver, raised in rather a handsome pattern over a ground of
blue enamel; and I think I can distinguish a cypher of R. B. at each
corner of the enchased work. On the dial-plate is written _Robertus B.
Rex Scotorum_, and over it is a convex transparent horn, instead of the
glasses which we use at present. Now _Robertus B. Rex Scotorum_ can be
no other king of Scotland than Robert Bruce, who began his reign in
1305, and died in 1328; for the Christian name of Baliol, who succeeded
him, was Edward; nor can _Robertus B._ be applied to any later Scottish
king. This very singular watch is not of a larger size than those which
are now in common use; at which I was much surprised till I had seen
several of the sixteenth century in the collection of Sir Ashton Lever
and Mr. Ingham Forster, which were considerably smaller.
As I mean to deduce the progress of the art of clock-making in a
regular chronological series, the next mention I find of _horologia_ is
in Rymer’s Fœdera, where there is a protection of Edward III., in the
year 1368, to three Dutchmen, who were _Orlogiers_. The title of this
protection is, “De horologiorum artificio exercendo;” and I hope to
have sufficiently proved that there was no necessity of procuring mere
dial-makers at this time.
Clock-makers however were really wanted at this period of the
fourteenth century, as may be inferred from the following lines of
Chaucer, when he speaks of a cock’s crowing:--
Full sikerer was his crowing in his loge,
As is a _clock_, or any abbey orloge[1098]:
by which, as I conceive at least, our old poet means to say, that
the crowing was as certain as a _bell_ or abbey-_clock_[1099]. For
though we at present ask so often, “What is it _o’clock?_” meaning the
time-measurer, yet I should rather suppose, that in the fourteenth
century the term _clock_ was often applied to a _bell_ which was rung
at certain periods, determined by an hour-glass or a sun-dial. Nor have
I been able to stumble upon any passage which alludes to a clock,
by that name, earlier than the thirteenth year of the reign of Henry
VIII.[1100] The abbey _orloge_ (or clock) however must have been not
uncommon when Chaucer wrote these lines; and from clocks beginning
to be in use we might have had occasion for more artificers in this
branch, though it should seem that we had Englishmen, who pretended
at least to understand it, because the protection of Edward III.
above-cited, directs that the persons to whom it was granted, should
not be molested whilst they were thus employed.
I now pass on to a famous astronomical clock, made by one of our
countrymen in the reign of Richard II., the account of which I have
extracted from Leland. Richard of Wallingford was son of a smith,
who lived at that town, and who, from his learning and ingenuity,
became abbot of St. Albans. Leland, speaking of him, says, “Cum jam
per amplas licebat fortunas, voluit illustri aliquo opere, non modo
ingenii, verum etiam eruditionis, ac artis excellentis, miraculum
ostendere. Ergo talem _horologii_ fabricam magno labore, majore
sumtu, arte vero maxima, compegit, qualem non habet tota Europa, _mea
opinione_, secundam, sive quis cursum solis ac lunæ, seu fixa sidera
notet, sive iterum maris incrementa et decrementa[1101].” Richard of
Wallingford wrote also a treatise on this clock, “Ne tam insignis
machina vilesceret errore monachorum, aut incognito structuræ ordine
silesceret.” From what hath been above stated, it appears that this
astronomical clock continued to go in Leland’s time, who was born at
the latter end of Henry VII.’s reign, and who speaks of a tradition,
that this famous piece of mechanism was called _Albion_ by the inventor.
Having thus endeavoured to prove that clocks were made in England from
the time of Edward I. to that of Richard II., it is not essential
to my principal purpose to deduce them lower through the successive
reigns; but when I have shortly stated what I happened to have found
with regard to this useful invention in other parts of Europe, I shall
attempt to show why they were not more common in the thirteenth and
fourteenth centuries.
The citation from Dante, which I have before relied upon, shows that
they were not unknown in Italy during that period; and M. Falconet,
in Mémoires de Litterature, informs us, that a James Dondi, in the
fourteenth century, assumed from a clock made by him for the tower of
a palace, the name of _Horologius_, which was afterwards borne by his
descendants.
In France, or what is now so called, Froissart mentions, that during
the year 1332, Philip the Hardy, duke of Burgundy, removed from
Courtray to his capital at Dijon a famous clock which struck the
hours, and was remarkable for its mechanism[1102]. The great clock
at Paris was put up in the year 1370, during the reign of Charles
V., having been made by Charles de Wic[1103] a German. Carpentier,
in his supplement to Du Cange, cites a decision of the parliament of
Paris in the year 1413, in which Henry Bye, one of the parties, is
styled _Gubernator Horologii palatii nostri Parisiis_[1104]. About the
same time also the clock at Montargis was made, with the following
inscription:--
Charles le Quint (sc. de France)
Me fit par Jean de _Jouvence_.
The last word seems to be the name of a Frenchman.
Though I have not happened to meet with any mention of very early
clocks in Germany, yet from the great clock at Paris in 1370 being the
work of De Wic, as also from the protection granted by Edward III.
to three clock-makers from Delft, it should seem that this part of
Europe[1105] was not without this useful invention; and the same may
be inferred with regard to Spain from the old saying, “Estar como un
relox[1106].”
Having now produced instances of several clocks, and even a watch,
which were made in different parts of the fourteenth century, as also
having endeavoured to prove that they were not excessively uncommon
even in the thirteenth, it may be thought necessary that I should
account for their not being more generally used during those periods,
as in their present state at least they are so very convenient. For
this it should seem that many reasons may be assigned.
In the infancy of this new piece of mechanism, they were probably of
a very imperfect construction, perhaps never went tolerably, and were
soon deranged, whilst there was no one within a reasonable distance to
put them in order. To this day the most musical people have seldom a
harpsichord in their house, if the tuner cannot be procured from the
neighbourhood. We find therefore that Henry VI. of England, and Charles
V. of France, appointed clock-makers, with a stipend, to keep the
Westminster and Paris clocks in order.
It need scarcely be observed also, that, as the artists were so few,
their work must have been charged accordingly, and that kings only
could be the purchasers of what was rather an expensive toy than of
any considerable use. And it may perhaps be said, that they continued
in a great measure to be no better than toys till the middle of the
seventeenth century. Add to this, that in the thirteenth and fourteenth
centuries, there was so little commerce, intercourse, or society, that
an hour-glass, or the sun, was very sufficient for the common purposes,
which are now more accurately settled by clocks of modern construction.
Dials and hour-glasses likewise wanted no mending.
Having now finished what hath occurred to me with regard to the first
introduction of clocks, I shall conclude by a few particulars, which
I have been enabled to pick up, in relation to those more portable
measurers of time, called _watches_, the earliest of which, except
that of Robert Bruce, king of Scotland, seems to be one in Sir Ashton
Lever’s most valuable museum, the date upon which is 1541[1107].
Derham, in his Artificial Clock-maker[1108], published in 1714,
mentions a watch of Henry VIII. which was still in order; and Dr.
Demainbray informs me, that he hath heard both Sir Isaac Newton and
Demoivre speak of this watch[1109]. The emperor Charles V., Henry’s
contemporary, was so much pleased with these time-measurers, that he
used to sit after his dinner with several of them on the table, his
bottle being in the centre[1110]; and when he retired to the monastery
of St. Just, he continued still to amuse himself with keeping them in
order, which is said to have produced a reflection from him on the
absurdity of his attempt to regulate the motions of the different
powers of Europe.
Some of the watches used at this time seem to have been strikers; at
least we find in the Memoirs of Literature, that such watches having
been stolen both from Charles V. and Lewis XI. whilst they were in a
crowd, the thief was detected by their striking the hour[1111]. In
most of the more ancient watches, of which I have seen several in the
collection of Sir Ashton Lever and Mr. Ingham Forster, catgut supplied
the place of a chain[1112], whilst they were commonly of a smaller
size than we use at present, and often of an oval form[1113].
From these and probably many other imperfections, they were not in any
degree of general request till the latter end of queen Elizabeth’s
reign. Accordingly in Shakspeare’s Twelfth Night, Malvolio says, “I
frown the while, and perchance _wind up my watch_, or play with some
rich jewel.” Again, in the first edition of Harrington’s Orlando
Furioso, printed in 1591, the author is represented with what seems to
be a watch, though the engraving is by no means distinct, on which is
written “Il tempo passa[1114].”
In the third year of James I., a watch was found upon Guy Fawkes, which
he and Percy had bought the day before, “to try conclusions for the
long and short burning of the touch-wood, with which he had prepared to
give fire to the train of powder[1115].”
In 1631, Charles I. incorporated the clock-makers; and the charter
prohibits _clocks_, _watches_, and _alarms_, from being imported; which
sufficiently proves that they were now more commonly used, as well
as that we had artists of our own who were expert in this branch of
business.
About the middle of the seventeenth century, Huygens made his great
improvement in clock-work, which produced many others from our own
countrymen[1116]; the latest of which was the introduction of repeating
watches, in the time of Charles II., who, as I have been informed by
the late lord Bathurst, sent one of the first of these new inventions
to Lewis XIV. The former of these kings was very curious with regard
to these time-measurers; and I have been told by an old person of the
trade, that watchmakers, particularly East, used to attend whilst he
was playing at the Mall; a watch being often the stake.
But we have a much more curious anecdote of royal attention to watches
in Dr. Derham’s Artificial Clock-maker (p. 107). Barlow had procured
a patent, in concert with the Lord Chief Justice Allebone, for
_repeaters_; but Quare making one at the same time upon ideas he had
entertained before the patent was granted, James II. tried both, and
giving the preference to Quare’s, it was notified in the gazette. In
the succeeding reign, the reputation of the English work in this branch
was such, that in the year 1698, an act passed, obliging the makers
to put their names on watches, lest discreditable ones might be sold
abroad for English[1117].
_Letter on the pretended Watch of King Robert Bruce_[1118].
You will remember that I formerly mentioned something to you in
reference to the observations made by the Hon. Daines Barrington, on
the earliest introduction of clocks, published in the Annual Register
for 1779, under the article Antiquities, p. 133. According to your
desire, I will communicate what circumstances come within my personal
knowledge, about a watch that corresponds very much to one described
by him as once the property of king Robert Bruce. I must be indulged,
although in some particulars I cannot speak with absolute certainty,
as so much time hath elapsed since the transaction I am going to relate.
Being early fond of anything ancient or uncommon, I used to purchase
pieces of old coin from a goldsmith who wrought privately in Glasgow,
and sometimes went about as a hawker. Having often asked him from the
curiosity of a boy, if he had ever been at the castle of Clackmannan,
or heard of any antiquities being found there, he told me that he had
purchased from Mrs. Bruce, who is the only survivor of that ancient
family in the direct line, an old watch, which was found in the castle,
and had an inscription, bearing, that it belonged to king Robert Bruce.
I immediately asked a sight of it; but he told me it was not at hand.
He fixed a time for showing me this invaluable curiosity; but even then
it could not be seen. My avidity produced many anxious calls, although
by that time I began to suspect he meant to play upon me, especially
as I did not think it altogether credible that Mrs. Bruce would sell
such a relict of her family if she had ever had it in her possession.
At length I was favoured with a sight of it. The watch, as far as I
can recollect, almost entirely answered the one described. It had a
ground of blue enamel. It had a horn above the dial-plate instead of a
glass. The inscription was on the plate. But whether it was _Robertus
B._ or _Robertus Bruce_, I cannot remember. The watch was very small
and neat, and ran only, to the best of my knowledge, little more than
twelve hours, at least not a complete day. The Hon. Mr. Barrington does
not mention anything about this circumstance. It is about twelve years
since I saw it. Whether there be any castle in Fife properly called
Bruce castle, I know not; but the castle of Clackmannan hath always
been the residence of the eldest branch of the family; and although the
town in which it stands now gives name to a small county, yet in former
times, and still in common language, that whole district receives the
name of Fife, as distinguishing it from the county on the other side
of the firths of Forth and Tay. The first thing that occurred to me
about the watch itself, was in regard to the inscription. Observing
that all the coins of king Robert’s age bore Saxon characters, I could
not believe the inscription to be genuine, because the characters
were not properly Saxon, but a kind of rugged Roman, or rather Italic
characters, like those commonly engraved, but evidently done very
coarsely, to favour the imposition. He valued it at 1_l._ 10_s._, but I
would have nothing to do with it. The first time I had an opportunity
of seeing Mrs. Bruce of Clackmannan, after this, I asked her if such a
watch had ever been found. She told me that she never so much as heard
of any such thing. This confirmed the justness of my suspicion.
I paid no further regard to this story till about seven years ago, when
I received a letter from a friend, informing me, that a brother of his
in London, who had a taste for antiquity, had desired him, if possible,
to procure some intelligence from Glasgow about a watch, said to be
king Robert Bruce’s, which had thence found its way to London, and
was there making a great noise among the antiquaries. I then applied
to my former goldsmith, who was then in a more respectable way, and
mentioned the old story. He immediately fell a-laughing, and told me,
that he did it merely for a piece of diversion, and thought the story
would take with me, as I had been often asking about the place. He said
that it was an old watch brought from America; that, to get some sport
with my credulity, he had engraved the inscription upon it in a rough,
antiquated-like form; that he had afterwards sold it for two guineas;
he had learned that it was next sold for five, and had never more heard
of it.
However early the invention of clocks might be, I am greatly mistaken
if any authentic documents can be produced of the art of making
pocket-watches being discovered so early as the beginning of the
fourteenth century. Lord Kaimes, somewhere in his Sketches of Man,
asserts, that the first watch was made in Germany, so far as I can
remember, near the close of the fifteenth century[1119]. If any watch
had been made so early as R. Bruce’s time, it is most likely the
inscription would have been in Saxon characters, as not only the money
both of Scotland and England, but of Germany, in that age, bears a
character either Saxon, or greatly resembling it.
Whatever ardour one feels for anything that bears the genuine marks
of antiquity, it is certainly a debt he owes to those who have the
same taste, to contribute anything in his power that may prevent
impositions, to which antiquaries are abundantly subject, through the
low humour or avarice of others; or that may tend to confirm a fact by
proper comparison and minute investigation of circumstances. Besides,
this is of greater moment than settling the genuineness of a coin, or
many other things of the same nature, because it involves in it the
date of a very important discovery. It doth not merely refer to the
history of an individual, or even of one nation, but to the history of
man. It respects the progress of the arts; and an anachronism here is
of considerable importance, because, being established upon a supposed
fact, it becomes a precedent for writers in future ages.
[The time and place at which watches were first made similar to those
now in use, are not positively determined. The first step towards
its accomplishment must have consisted in making a mainspring the
source of motion instead of a weight[1120]. The invention of the fusee
speedily followed the mainspring, and without it the former would be
useless, in consequence of its tension varying according to the size
of its coil. In the time of Elizabeth a watch was a very different
kind of instrument to one of the present day. As regards size, it
closely resembled one of our common dessert-plates. Before Dr. Hooke’s
improvement, the performance of watches was so very irregular that
they were considered as serving only to give the time for a few hours,
and this in rather a random kind of way. The invention by Dr. Hooke
of a spiral spring applied to the arbor of the balance, by which
means effects were produced on its vibrations similar to the action
of gravity on the pendulum of a clock, was perhaps of more importance
than any improvement which has been subsequently made. Watches
were common in France before 1544, as in that year the corporation
of master clockmakers in Paris had a statute enacted to ensure to
themselves the exclusive privilege of making and causing to be made
clocks and watches, large or small, within the precincts of that city.
The anchor-escapement was invented by Clement, a London clockmaker,
in 1680. Previously to 1790, two kinds of watches were made, the
vertical and the horizontal. The former was first used in clocks, then
in watches. The horizontal was invented in 1724, by George Graham,
F.R.S. (an apprentice of the renowned Tompion), to whom we are indebted
for two of the most valuable improvements in clocks which have ever
been made, viz. the dead-beat, or Graham escapement[1121], as it is
called, and the mercurial compensation pendulum. The best proof that
can be adduced of the importance of these inventions is, that they
still continue to be employed in all their early simplicity, in the
construction of the best astronomical clocks of the present day.
Graham’s horizontal escapement is still extensively employed in the
Swiss and Geneva watches, but in the better sort of those of English
manufacture, it has been superseded by the duplex, and recently by
the lever, which is nothing more than the application of Graham’s
dead-beat escapement to the watch, though patents have been taken out
by various persons who have claimed the invention. The most remarkable
inventions of this period were those of Harrison, consisting of his
gridiron pendulum, the going fusee, the compensation curb, and the
remontoir escapement. In 1736, he appears to have completed his
longitude watch, and received from the Royal Society their gold medal;
he ultimately received the government reward of £20,000, together with
other sums from the Board of Longitude and the Honourable East India
Company. Notwithstanding his application of the compensation curb to
the watch, it was still a subject of inquiry, and by many persons it
was thought that the expansion and contraction of the metal, of which
the spring is composed, was the source of variation in the equality
of its motion under changes of temperature; but the consideration
that the change of rate in the clock, with a seconds pendulum, in
passing from the winter to the summer temperature, amounted only to
about twenty seconds, while that of the watch exceeded six minutes and
a half under similar circumstances, led careful observers to infer
that some other cause must be assigned for the anomaly, and the loss
of elasticity of the balance-spring by heat began to be suspected,
as appears by the following passage in the Prize Essay of Daniel
Bernoulli, read before the French Academy:--“I must not omit (said
this celebrated geometrician) a circumstance which may be prejudicial
to balance watches; it is, that experimental philosophers pretend to
have remarked that certain changes of elastic force uniformly follow
changes of temperature. If that be the case, the spring can never
uniformly govern the balance.” That which Bernoulli only conjectured,
was in 1773 established as a matter of certainty, and the amount in
loss of time due to each of the three conjointly operating causes
determined by Berthoud to be,--loss by expansion of the balance, 62
seconds; loss by elongation of the balance-spring, 19 seconds; and
loss by the diminution of the spring’s elastic force by heat, 312
seconds, by an increase of 60° of heat of Fahrenheit’s scale. We have
previously observed that Harrison’s compensation curb was inefficient,
as besides other defects, it interfered too much with the isochronism
of the balance-spring, as the inventor himself was candid enough to
confess that the balance, balance-spring, and compensation curb,
were not contemporaneously affected by changes of temperature, since
small pieces of metal were sooner affected than large, and those in
motion before those at rest. Whence he was led to conclude, that if
the provision for heat and cold could properly reside in the balance
itself, as was the case with his gridiron pendulum clocks, the
time-piece might be made much more perfect. This ingenuous observation
is the more to Harrison’s credit, as it was certainly his interest
to conceal such a suggestion, being at that time a candidate for the
government reward. The complexity of Harrison’s timekeeper and the
high price, £400, demanded by Kendall to make them after that model,
still left the timekeeper to be discovered that would come within the
means of purchase of private individuals: for admirably as Harrison
had succeeded in the construction of those which had procured him his
reward, and great as were the talents of his assistant Larcum Kendall,
yet for practical purposes, there needed an instrument of greater
simplicity, and to John Arnold we are indebted for its invention.
Arnold is also celebrated for the manufacture of the smallest
repeating-watch ever known: it was made for his majesty George III., to
whom it was presented on his birthday, the 4th of June 1764. Although
less than six-tenths of an inch in diameter, it was perfect in all its
parts, repeated the hours, quarters and half-quarters, and contained
the first ruby cylinder ever made. Indeed so novel was the construction
of this little specimen of mechanical skill, that he was forced not
only to form the design and execute the work himself, but also to
manufacture the greater part of the tools employed in its construction.
It is minutely described in Rees’s Cyclopædia, and also in the Sporting
Magazine of that time, in which latter work it is correctly stated to
be of the size of a silver twopence, and its weight that of a sixpence.
The King was so much pleased with this rare specimen of mechanical
skill, that he presented Mr. Arnold with 500 guineas; and the Emperor
of Russia afterwards offered Mr. Arnold 1000 guineas for a duplicate of
it, which he declined.
Arnold’s model, though destined to perform the same office as
Harrison’s, was entirely different in its construction, and was as
simple as his predecessor’s was complex. By progressive stages of
improvement, it was brought by the inventor himself to so high a
point of perfection, that it continues to be the model followed in
the construction of the best chronometers of the present day. The
instruments upon which Arnold experimented are now in the possession
of his successor, Mr. C. Frodsham, and show the gradual progress of
advancement made in the escapement, &c., until he arrived at that
beautiful, yet simple, detached escapement, which is still followed,
and known under the name of the Arnold escapement. He was the first
watchmaker who introduced jewelling into watches and clocks, and in
1771 he applied ruby pallets to the two clocks of the Royal Society
by Graham and Smeaton, and likewise to the transit clock by Graham
at the Royal Observatory, Greenwich. In 1776 Arnold achieved what
was unquestionably his greatest work, viz. the invention of the
cylindrical spring and compensation balance, and their application in
the chronometer, which is the name that Arnold then first employed
to designate his timekeepers. This ingenious and valuable discovery
introduced a new æra in chronometry. Each part of the machine under
the new arrangement performed unchecked the office assigned to it. The
escapement was completely detached, except at the moment of discharge
and giving impulse; the balance-spring, no longer interfered with in
corrections for temperature (as formerly) by the compensating curb,
became a free agent and the generator of motion, in which state only
it is capable of being perfectly isochronized; the balance, by its
expansion and contraction, varied its inertia according to the varied
tension of the balance-spring by its increased or diminished elastic
force in changes of temperature, while the office of the main-spring
was reduced to that of a simple maintaining power. This beautiful
discovery, together with the law of isochronism and other important
improvements in the modification of the compensation balance, procured
for him and his son John Roger Arnold the reward from government of
the sum of £3000. The accuracy with which _chronometers_ keep time is
truly astonishing: in 1830 two chronometers constructed by Mr. Charles
Frodsham were submitted for public trial at the Royal Observatory,
Greenwich, for twelve months, and were observed daily. One of them made
an extreme variation of 86-hundredth parts of a second, and the other
of 57-hundredths only; but even this degree of accuracy, surprising
as it is, is surpassed by the performance of his best _astronomical_
clocks. It is therefore highly honourable to the English artists, that
by their ingenuity and skill they have accomplished the great object
which had occupied the attention of the learned of Europe for nearly
300 years, namely, the means of discovering the longitude at sea. It is
not a little singular that Sir Isaac Newton suggested the discovery of
the longitude by the aid of an accurate timekeeper.
If we go back to the period of Philip III. of Spain, we shall then
see the interest and importance attached to this great discovery. As
early as 1598, this monarch offered a reward of 100,000 crowns to any
person who should discover the means of finding the longitude of a
ship at sea; but what was the opinion then entertained of the nature
of the task to be accomplished by means of the balance-watches then
in use, may be gathered from an expression of Morin, who wrote about
the year 1630, and who in speaking to the Cardinal Richelieu of the
difficulty of constructing an instrument which should keep time to the
requisite degree of accuracy for that purpose, is reported to have
said, “Id verò an ipsi dæmoni nescio, homini autem suscipere scio esse
stultissimum[1122].”
We have not said much on the beautiful discovery of the law of
isochronism, of the balance-spring, on which the higher adjustment
of clocks and watches so entirely depend, as an elaborate essay on
this subject by Charles Frodsham, F.R.A.S., is in the hands of the
publisher, and will shortly be circulated.
Some very ingenious contrivances have within the last few years been
effected in the application of the electric fluid as a source of motive
power to clocks and chronometers, and they offer peculiar advantages
in the great simplicity of the apparatus in which wheels are dispensed
with, hence friction is reduced to a minimum. Their invention is a
subject of dispute between Professor Wheatstone and Mr. Alexander
Bain[1123]. We shall briefly describe Mr. Bain’s clock. His source of
electricity is obtained by fixing galvanic plates in moist earth. The
clock consists of a pendulum, the bob of which vibrates between the
poles of two permanent magnets, the opposite poles of which face one
another. A small platinum-ball is affixed to the upper part of a small
brass stem, which is free for lateral motion, being fastened below to
a light spindle carried by the upper part of the pendulum-rod. A wire
coated with silk is attached to the lower end of the suspension-spring
of the pendulum. It is led down the back of the rod (which is composed
of wood) and then coiled longitudinally in many convolutions around
the edge of the bob in a groove. It is then taken up the back of the
rod and terminates in the bearings of the spindle. The pendulum is
suspended from a metal bracket fixed to the back of the case, and to
which one of the poles of the battery is attached. Two pins are fixed
horizontally, parallel with the platinum-ball, leaving space for its
lateral motions, and at such a distance that the ball alternately
comes into contact with each pin, when the pendulum has reached the
opposite extremity of its arc. The other pole of the battery is
placed in contact with the metal bracket which supports one of the
pins. As long as the platinum-ball rests on the pin projecting from
the pin-bracket to which the second pole of the battery is attached,
a constant current of electricity is established and passes through
the earth, the plates and the wires. But when the pendulum is set in
motion by being drawn on one side, the point of support of the rod
carrying the platinum-ball is thus moved to the same side, hence the
centre of gravity of the platinum-ball being removed beyond its base,
it falls upon the opposite pin. This motion of the ball lets on and
cuts off the flow of electricity, at or near the ends of the vibrations
of the pendulum, so that the convoluted wire of the bob is alternately
attracted and repelled by the magnets at the proper points of its
vibrations, and thus a continual motion is kept up. Mr. Bain has also
contrived arrangements by which a great number of clocks may be worked
simultaneously or in rotation; as also by which ordinary clocks may be
made to keep time. The latter are effected by transmitting a current
of electricity once in every four hours from a regulating clock. As
the details connected with these valuable contrivances can hardly be
followed without figures, we must rest satisfied with referring the
reader to Mr. Bain’s work, before cited.]