H O II O 
According to Dr. Derham, the oldeft Englifh clock ex¬ 
tant is in a turret of the palace at Hampton Court, con¬ 
tracted in the year 15+0, which time was in the reign of 
king Henry VIII. by a maker whole initials are N. O. 
When we eoniider that this clock contains mechanifm 
for rep relenting the motions of fome of the heavenly bo¬ 
dies, and that the celebrated Copernicus was living at the 
time of its date, and had not publilhed- his book On the 
Revolutions of the Celeftial Orbs ; when we reflect alfo, 
that more than a century elapfed after this time before 
the pendulum was applied as the regulator of clocks j 
thefe confiderations appear fufficiently interefling to in¬ 
duce a minute examination of this ancient clock, parti¬ 
cularly of that part of it which conllitules its celeltial 
mechanilm. The account of the wheel-work which pro¬ 
duces the-celeftial motions, from Dr Derham’s Artificial 
Clock-maker, publilhed in 1714 (third edition,) we lhall 
copy in i;is own words. “The Hampton- Court clock,” 
fays the doctor, <£ fhows the time of the day, and the mo¬ 
tion of the fun and moon through all the degrees of the 
zodiac, together with the matters depending thereon, as 
the day of the month, the fun’s and moon’s places in the 
zodiac, moon’s fouthing, &c. To flio'w how completely 
(for that age) the wheel-work is laid under the moving 
part of the dial-plate, I have given the calliper thereof, 
which reprefents the feveral wheels and pinions only 
which lie under the dial-plate, and drive the feveral mo¬ 
tions in this manner. In the centre of all, both the dial- 
plate and its wheel-work are placed on a fixed arbor, 
which hath a pinion on the end of it, which drives both 
the folar and lunar motions, by means of a large wheel of 
2SS teeth turning round upon it once in 24 hours, which 
large wheel is drawn round by a pinion of 12, fixed on 
the arbor of the great wheel within the clock, which 
turneth round once in an hour. The wheel 28S, thus 
turning round in 24 hours, carries about with it the 
wheel 37, and its pinion of 7 leaves, as alfo the other 
prickt (dotted) wheel, and its pinion, on the other fide. 
The pinion 7, of the wheel 37, drives another wheel of 
45 teeth, which carries round the moon’s ring or circle. 
On the oppofite fide the aforelaid pinion 8 drives round 
the prickt wheel, whole pinion drives a wheel of 29 teeth, 
whole pinion, of 12 leaves, drives round the wheel 132 
that/carries the fun and the zodiacal matters. Thefe were 
the numbers of the wheel-work (continues the doftor) 
remaining in the year 1711; but the prickt wheel and pi¬ 
nion were taken out formerly by fome ignorant work¬ 
man that was not able otherwife to amend the clock; but 
were l'upplied, and the whole movement repaired lately, 
by that ikilful artift, Mr.-Lang. Bradley, in Fenchurch- 
Itreet, London.” 
Bradley however made more alterations than thefe, or 
the clock mull have fince been very confiderably altered 
indeed ; for at prefent the whole of both the annual and 
lunar movements are different from the original ones re¬ 
corded by Dr. Derham. 
The lunar movement is 11 = 29 | days, and the 
IO 9 
73 A2 130 
•annual one — -j- — +—= 365 • exactly. The prefent 
central pinion is a double one confifting of a 10 an*’ a 12, 
fixed as the former one of 8 is defcribed to have been, 
and pinned together; they are made of box, as are alfo 
•the pinions of 7 and 9, to prevent their cankering, or 
cxyding as it is now called ; and both the trains are ar¬ 
ranged as-already decribed. The wheel, of 42 is made of 
brals; but the reft, being very large, are made of iron'. 
The great wheel of 288, which connects the clock-work 
with the aftronomical movements, appears to be the only 
portion of the original work, bc-th by its marks of anti¬ 
quity- and the number of its teeth, which are cut on the 
inner edge of its circular part; there are two crofs bars 
riveted to this indented rim to carry the, heavenly move¬ 
ments; and,vas! there is no counterpoif'e to thefe, it was 
•lufipe&ed at the time that .their rifmg and falling weight 
LOGY. 327 
would alternately accelerate and retard the going of the 
clock, which is connefted with it by means of an hori¬ 
zontal arbor about three yards long by eftimation ; ac- 
cordingly, on inquiry, it turned out that the time of the 
day indicated is lonietimes 5 minutes or more too back, 
and again as much too forward on the Jame day, every 
day, which circumllance had not before been accounted 
for. 
The infcription “ L. Bradley, 1711,” is marked on the 
frame of the going-part of the clock, which has evidently 
been new, either all of it at that time, or fome part of it 
fince, fo that what the original regulator was, does not 
appear, nor are the initials N. O. to be found at prefent. 
There are three barrels and weights, one for the going- 
part, which has a very heavy long pendulum; one for the 
ftriking-part; and one for linking the quarters': the pre¬ 
fent fcapement is a pair of pallets acting alternately into 
pins projecting from the plane of a wheel .with a horizon¬ 
tal arbor, which kind is now pretty common in England, 
and, according to Berthoud, was invented by M. Amant, 
a clock-maker at Paris, late in the eighteenth century. 
In Grole’s Antiquities it is faid that this clock, confi- 
derecl as an allronomical clock, was invented by Tom- 
pion ; but this account cannot be true, becaufe that fa¬ 
mous artift lived in Dr. Derham’s time, a century and 
half after the original conftruftion ; he may in all proba¬ 
bility-have been employed in making fome of the altera¬ 
tions, either in the aftronomical or going part. 
The hand and divided circles are in the following or¬ 
der on the face, viz. 1. Or inmoft lmall circle—twice 
XII for moon’s fouthing. 2. Moon’s age, 29J. 3. Eclip¬ 
tic with figns and days of the month.. 4. Sun and hour 
hand revolving in 24'hours. 3.Twenty-four hours, marked 
L II. See. The moon’s phafe is (liown by a circular hole 
cut on the hour-index, covering more or lefs of a black¬ 
ened plate placed under it on the lunar dial. 
There is faid to be a clock at Padua, of the date of 
1438, which points out the hour of the day, the days of 
the month, the motion of the fun through the twelve 
figns of the zodiac, and the afpefts of the moon. How¬ 
ever, we lhall detain the reader no longer upon the fub- 
jeft of ancient, and imperfect machines, but proceed im¬ 
mediately to. deferibe the common thirty-hour clock ac¬ 
cording to the prefent improved conftruftion. On the 
Horology Plate IX. fig. 56 reprefieiits the profile of inch a 
clock: P is a weight that is fufpended by, ; a rope that 
wind.* about the cylinder or barrel C, which, is fixed upon 
the axis a, a ; the pivots b, b, go into holes made in the 
plates TS, TS, in which they turn freely. Thefe plates 
are made of brafs or iron, and are connefted by means of 
four pillars Z,Z, of which only two can be feen in the plate ; 
and the whole together is called the frame; The weight 
P, if not reftrained, would nec-ellarily turn the barrel C 
with an uniform accelerated motion, in-the fame manner 
as if the weight were tailing freely from a height. But 
the barrel is furnilhed with a ratchet-wheel KK, fig. 57, 
the right fide of Whole teeth ftrikes again!! the click, 
which is fixed with a ferew to the wheel D D, fo that the 
aftion of the weight is communicated to the wheel DD, 
fig. 56 ; the teeth of which aft upon the teeth of the fmall 
wheel d , which turns upon the pivots cc. The commu¬ 
nication or aftion of one wheel with another is called the 
pitching. Seven'll things are requisite t.o fojun a good pitch¬ 
ing, the advantages of which are obvious .in all machinery 
where teeth and pinions are employed. 
The wheel EE is fixed upon the-axis of- the pinion T; 
and the motion communicated to the wheel DD by the 
weight is tranfmitted to the pinion <4 consequently to the 
-wheel EE, as likewife to ,the pinion e and wheel- F F, 
which moves-the pinion f upon the axis of which the 
crown or balance-wheel GH is fixed. The pivots, of the 
pinionyplay in holes of the plates LM, which.are fixed 
horizontally to the plates T S. In a word, the-motion 
begun by the vveight is tranfmitted from the wheel GH 
to the pallets IK, and by means of the fork U X, riveted 
on the axis, of the pallets, communicates motion to the 
-pendulum- 
