S£6 HOROLOGY 
train for more than from five to ten, or perhaps a few 
more, of its vibrations, on account of the inferiority of 
the power, which, he fuppofes, its fpring will have in 
continuing its motion, independent of the train, to that 
which gravity poflefTes in moving the pendulum. 
Of the inventions here described, we prefer that moft 
on which Mr. Congreve feems to place leaft value, by the 
flight manner in which he mentions it. The importance 
of improvements in modes of meafuring time, depends 
chiefly on their being applicable to nautical purpofes ; 
and of all thofe mentioned, the laft is the only one which 
can be of any ufe at fea. We have great hopes that far¬ 
ther trials .and experience will fhow how to make this 
principle add fo much to the accuracy of chronometers, 
that the longitude may be afcertained by them at lea to a 
greater precifion than has hitherto been done, the great 
advantages of which are too well known to need any de¬ 
tail. The limits of the detachment of balances are rated 
too low by the patentee ; of which he may find a fatif- 
fa£tory proof in the experiments made by Defaguliers to 
determine the agency of friftion-wheels with a fpring- 
balance, which vibrated fifty times before it flopped, 
though loaded with a confiderable weight on its axis; and 
which, when quite free, moved fo long, that it was com¬ 
puted a point on the rim mull have traverfed a fpace 
equal to a mile. We may therefore expect, without be- 
ing too fanguine, that a balance-wheel may be fo con- 
ftrufted as to aft very well with a detachment of a minute 
in Mr. Congreve’s method; we imagine this will be heft 
effected by increafing the length of the balance-fpring; 
and the method propofed by the patentee, of “increafing 
the weight of the balance in proportion to the ftrength of 
the fpring,” fhould be tried with various lengths of fpring, 
till the belt ratio of the weight of the balance, to the 
length and ftrength of the fpring, for protrafting the du¬ 
ration of the detachment, fhould be difcovered. 
Chronometers of this description will require fo few 
parts, and fo little nice workmanfhip, that they may cer¬ 
tainly be fold to good profit, at a much inferior rate to . 
any yet made, and thus be within the reach of every 
commander of a fhip above the rank of a coafter. 
The principle of keeping time with a p rot rafted de¬ 
tachment, by balls running in inclined tubes, or troughs, 
is very ingenious; and as far as we know is new. In Mr. 
Nicliolfon’s Philofophical Journal, vol. x. p. 76, Mr. J. 
W. Bofvvell has propofed a method of regulating time by 
a ball moving in a trough, applied to a circular pendulum; 
and by a cylinder ofcillating on a cycloidal furface to 
ferve as a vibrating pendulum, which would be free from 
error caufed by expanfion or contraction of dimenfions ; 
and has, above a year fince, contrived a method of mak¬ 
ing the ofcillations of a ball in a cycloidal trough, aft in 
the fame manner; but none of thefe methods Were in¬ 
tended to continue the detachment of the vibration for 
more than a fecond. 
The rate at which balls roll on planes inclined in dif¬ 
ferent angles, fiias not as yet been reduced to any certain 
rules, and therefore muff for the prefent remain in inferior 
eftimation, as a means of meafuring time, to the rate at 
which bodies ofcillate in circular and cycloidal curves, 
which has been fo w.ell afcertained by our moft eminent 
philofophers and mathematicians; and for this reafon the 
method of regulating a time-keeper by a ball ofcillating 
in a cycloidal trough muft now be preferred to it. We 
do not pretend to determine exaftly what may be the rank 
as to accuracy which the ball and plane may attain as a 
regulator of time, when its principles are minutely invef- 
tigated ; but to give it in its prefent imperfeft form, the 
fuperiority to others, fo well known, which the patentee 
has done, before this inveftigation has taken place, is 
premature, and not flriftly philofophical. In the prefent 
hate of the queftion as to its accuracy, there however can 
be no doubt that it is very fufficient for the regulation of 
clocks for common purpofes, which can be made fo cheaply 
on this principle, that, if it ever comes into general ufe, 
there is fcarcply a cottager but may have the comfort of 
poflefling an inftrument for meafuring time at leaft correft 
enough for his occafions. 
The patentee has been erroneous in propofing brafs cfe- 
fleftors for deftroying the momentum of the rolling ball; 
if they were of leather, or fome other foft fubftance, they 
would in fome degree have the effeft propofed ; but brals 
is fo elaftic, that the ball would be reflefted from it with 
nearly the fame force with which it ftruck it; and have 
its momentum and velocity thus fo increafed at every 
turn, that it would run through the laft trough, or groove, 
in much lefs time than it did through the firlt; this re- 
flefting of the ball would alfo caufe it fometimes to leap 
over a part of the groove without touching it, which 
would be another caufe of inequality of motion, and of 
conlequent inaccuracy. 
Another deleft in the fame machine (for which a re¬ 
medy has been propofed by the patentee, that would ra¬ 
ther add to the inaccuracy than remove it,) arifes from 
the inequality of the time fpent in reverfing the inclination 
of the plane at the different turns ; no proviiion is made 
for equalizing this motion, and it is evident that every 
cafual inequality of the aftion of the prime mover muft 
caufe its velocity to vary, and that the changes of the 
denfity of the air, afting on fo large a furface as m 
fquare inches, muft alfo influence it confiderably, as the 
effeft of thefe will be multiplied in a duplicate ratio to 
this velocity; the refiftance of the air to a body in motion 
being in that proportion. 
Having thus cleared the way, by explaining the prin¬ 
ciples, upon which horological machines acl, and the na¬ 
ture of their component parts, we proceed to defcribe the 
machines themfelves, under the three heads of Clocks, 
Watches, and Time-keepers ; underfianding by the laft 
term fuch machines as cannot with flrift propriety be in¬ 
cluded under either of the former, though either or both 
of the former we are aware might be included under the 
latter. 
I. Of CLOCKS. 
From what has been faid in the introduftion to this 
article, and from the teftimonies which have been there 
adduced refpefting the origin of a clock, the conclulion 
to be drawn is, that this machine is neither of fo ancient 
a date as fome writers fuppofe, nor yet among thofe more 
recent inventions which are placed in the laft two cen¬ 
turies ; and that the inventor is not certainly known, 
Fer. Berthoud, who has written more volumes on the 
fubjeft of clock-work than any other man, concludes his 
refearches with a belief, founded in ftrong probability, 
that a clock is not the invention of any one man, but an 
affemblage of fucceffive inventions, each of which is wor¬ 
thy of a feparate contriver; for inflance—1_ Wheel-work 
was known in the time of Archimedes, a. The weight 
.applied as a maintaining power had at firft a fly, moft 
likely fimilar to that of a kitchen jack. 3. The ratchet- 
wheel and click, for winding up a heavy weight without 
detaching the teeth of the great wheel, was found the 
next indifpenfable contrivance. 4. The regulation of the 
'fly, depending on the Hate of the any was abandoned, and 
a balance fubftituted. 5. An efcapement confequently 
became neceflary; which, in conjunftio.n with the ba¬ 
lance, conftituted a more regular check upon the ten¬ 
dency which a falling weight has to accelerate its velo¬ 
city, than a fly ufed a regulator could of itfelf be. 6. The 
application of a dial-plate and hand, to indicate the hours, 
was the confequence of the regularity introduced into 
the going part of the mechanilin. And, laftly, the link¬ 
ing portion, to proclaim at a diftance, without the aid of a 
watching-man, the hour that was indicated ; completed 
the lift of inventions. Such a fucceflion of ingenious con¬ 
trivances, introduced by different men, to improve upon 
the .firil rude inftrument, is perfeftly analogous to the 
lucceflive improvements which the prefent clock has ex¬ 
perienced at different periods. 
According 
