HOROLOGY. 
and tlie warning-piece G has dropped off the pin in the 
other minute-wheel, the ftriking-train will be in motion, 
and turn the chime-barrel, which while it is playing, the 
pin at H prevents the hook from gathering up the rack. 
When the chftne has -done playing, the fmail fpring I 
pufhes the wheels 24 out of the teeth of the pin-wheel; 
and the pieces A, B, D, and E, return into the places as 
rep relented in the callipers; and then the clock ftrikes 
the hour. 
We muft next endeavour to give the reader an idea how 
a. communication is made from the barrel to the bells, 
which portion could not ealily be reprefented in the fame 
figure. But the figures 64 and 65 Ihow as much of the 
chime-mechanifm of an ordinary clock as will ferve for 
our prefent purpole: ABCD, fig. 65, conftitutes a por¬ 
tion of the clock-frame, of which one conneftir.g pillar 
only is Ihown; E is the chime-barrel, of brafs, nearly equal 
in length to the pillar, and of a diameter fufficient to ad¬ 
mit of diagonal rows of brafs or Iteel pins to lilt the ham¬ 
mer-tails F, in the fuccefiive order of a defcending oflave, 
while the barrel is revolving, there being eight hammers 
G, ufual'ly linking fucceffively againlt as many bells H, 
which are mounted concentrically, within one another, 
on a common axis held fall by the bearing-piece of Heel, 
I, fcrewed to the face of one of the plates at its lower 
extremity. The mechanifm connected with the ftrikiiig- 
part of the clock is fo ingenioully contrived and arranged, 
that at and after the firll quarter from any hour, it will 
repeat the oftave once; at and after the fecond quarter, 
it will repeat the fame twice; at and after the third, three 
times; and at and after the hour itfelf, four times; alio, 
whenever the oftave is repeated four times, the chime- 
part unlocks the ftriking-part, and allows the clock to 
llrike the laft hour as loon as the chimes have ceafed, but 
not before. K is a brafs frame fcrewed at the lower end 
acrofs the fide of the l’uperior part of the clock-frame, 
which holds the works, and has a brafs plate N, of ham¬ 
mered metal, attached to it by fcrews; this plate, N, is 
divided nearly to the top by eight parallel vertical Hits, 
made by a faw, which form lo many fprings; the ham¬ 
mers all turn upon a common fixed arbor near P, fig. 64, 
65, by means of a perforation made in each folid part P 
above the tails, which folid part has a llraight edge in 
each, sgainll the central point of which the refpeflive 
fpring bears a little above its inferior extremity, as 
lhovvn at fig. 64; this mode of applying a fpring gives it 
the advantage of performing two offices, for it.will not 
only keep the hammer-tail in its proper fituation, to be 
taken by a pin of the barrel, but will give a fmartnefs to 
its blow, and then reftore it to its original pofition, by 
afting alternately, partly above and partly below the cen¬ 
tral hole; which kind of action will readily be under- 
flood, by examining the opening joint of a pen-knife, and 
attending to the manner in which its fpring is applied. 
L is a cock fcrewed to the face of one of the plates of the 
frame, and holds the projecting pivot of the fly-wheel, to 
which the fly M is attached, with a fpring preffing againft 
it in fuch a manner as to hold it to the arbor of the wheel 
when the latter revolves, and yet to allow it to turn in a 
detached ftate, when the motion of the wheel is fuddenly 
arrefted at the conclufion of the chiming, which is a ne- 
ceffary precaution for preventing the dellruClive effeCl 
which might be produced by an inflantaneous check of 
the momentum of the fly. 
The chime-barrel here defcribed, is pricked for the per¬ 
formance of a repetition of the eight notes of the octave 
by a defcending gradation; but it might as ealily have 
been made to chime the fame fcale by an afcending gra¬ 
dation, or to play any hymn or other tune within the 
compafs of the eight notes, or even with more notes, by 
the addition of a few more bells; which is what we mult 
now proceed to explain. 
In making a chime-barrel for any given tune, there are 
certain necellary conditions to be attended to: Firft, the 
barrel mull be well turned in a lathe upon its own arbor, 
lb as to have the whole furface of its circumference-con- 
centrical, when revolving on its pivots. Secondly, the 
train of wheel-work, belonging to the chinic-work, muft 
make the barrel revolve in a fpace of time exactly equal; 
to what is required for playing the requilite tune on any 
other inftrument, which time may be exaftly limited by 
proportioning the fly on the laft wheel to the power of 
the weight or fpring that urges the firft wheel of the train. 
Thirdly, there muft be as many bells as the compafs of 
the propoled tune contains mufical notes, and alfo, as 
many rows of pegs inferted into parallel circular lines on 
the circumference of the barrel as there are hammers to- 
be lifted by them; and, laltly, the whole circumference 
of the barrel mull be divided into as many longitudinal 
parallelograms of equal breadth, as there are mufical bars 
in the propofed' tune, each of which muft be again fubdi- 
vided into as many parts as there are notes of the lowed: 
denomination, whether crotchets, quavers, or femi-qua- 
vers, in each bar; then the parallel dividing lines will 
correfpond to the bars, and the fubdivifions within will 
be the guides for placing the pegs in thofe bars reflec¬ 
tively: for inftance, fuppofe that the 100th Pfalm be re¬ 
quired to be played by a chime-clock of any defcription, 
and that the points on the barrel where the pegs or pins 
are to be inferted be required to be afcertained. 
In fig. 66, it will be feen that this pfalm is marked C> 
which implies, that the bar is meafured by four crotchets, 
or two minims, in each bar ; it is alfo obfervable that the 
quickeft note in the tune is a minim, of which denomi¬ 
nation two conftitute four crotchets, or one bar; confe- 
quently the bar mull be fubdivided into two parts, as ex- 
prefled by the dotted lines in the figure for the two firft 
bars on the chime-barrel; but, if the tune had contained 
any crotchets, the bar muft have been fuppofed to be di¬ 
vided into four parts; or, if quavers, into eight parts, 
&c. in order that each note might occupy its proportion¬ 
ate fpace within the bar. Now fuppofe the length of the 
barrel to be reprefented by the line DD, or dd, becaufe 
the compafs of the pfalm is juft one octave beginning and 
ending with D inclufively, the line I) D, or d d, mull be 
divided into feven equal parts, which will require eight 
points in each to includefthem, viz. D, E, F, G, A, B, C, 
D, and d, e, f, g, a, b,c, d ; then, becaufe.the whole pfalm 
contains 20 bars, the whole line, D d, which we a flump as 
equal to the circumference of the barrel, mult be divided 
into 20 equal parts, which we have made to fall oppolite 
their refpeblive bars, the better to elucidate our example. 
From the dividing points let llraight lines be drawn to 
complete the fquare, or parallelogram, as the cafe may be, 
and there will be a figure, DD dd,. with 8 X 20—160 
fmail fquares or parallelograms, which we will fuppofe to 
be on paper that will exactly cover the barrel when pall¬ 
ed round it, in order to convey a more diltindl idea of the 
method of afcertaining the true places of the pins on the 
barrel, which may be thus done: The pin belonging to 
the firft note, G, is reprefented by a dot upon the begin¬ 
ning of the line G#; now this note, being a femibreve, 
occupies a whole bar; no other note therefore can be in¬ 
ferted in the remaining fpace, but the next following pin 
muft be one whole bar forward; accordingly the next 
note, which is G alfo, is placed on the fame line, upon 
the beginning of the next bar; the fecond G is a minim, 
occupying but half a bar; it therefore requires the next 
fucceeding note, F, to be removed only half a bar ; namely 
to the interfeblicn of the lines F f and 2 2. The next note, 
E, Hands on the following bar-line, where it interfedjfg 
the line Ee; and the following note, D, the lovvefl note 
of the tune, Hands on the lowell line in the middle of the 
bar, (at the interfe£lion.of the lines ~Dd and 3 3,) to com¬ 
plete the meafure ; each note occupying half a bar only 
till we come to the fifth and fixth bars, which are fimilar 
to the firft. We might thus have analyfed the whole 
furface of the barrel, lb far as relates to this pfalm ; but 
it 
