FUS 
‘indeed, hav eeegie AS oi oe under the articles 
HRONOMETER a K; but as eens on which 
the fhape of the fufee co. has oe (o a ed to, it 
is necellary that we fhould treat the fubje@t more ae 
in this .piace 
The fteel arbor, that -paffes through the {pri ng-box, has 
a fquare on its protruding end, on which a itrong ratchet- 
wheel i is inferted ; ar nda catch, with a fpring prefling on it, 
crewed to one of the plates of the frame of the works, 
alw ays holds it falk i in any pofition given it; fo that the box 
will turn freely, when urged round, Gitiout any motion in 
its hon ; upon this fixed arbor is a ftud within the box, 
on which the interior end of the {pring, intended for the 
e near the ex- 
maintaining power, is ho a hole ma 
remity of the faid fpring; while the exterior end of the 
fame {pring is pinned to the fide of th , the convex 
diameter of the ie depends upon the len 
and thicknefs of the {pring conjointly ; the ftrength of ‘the 
f; pring depends upon its breadth @ nd thicknefs taken t toge- 
ther, when of a given — ; and the time i‘. halen continue 
to act at once coiling up, or winding, as called, will 
depend aly on its length, - part y on its ‘rengtl, ow 
as the time in which the F ufee is made volve on 
be ae ed by the whole time t dat the machine 1 is bee aed . 
go at once winding, divided by the number of effective {pi- 
rals or ae on the fufee, when the fpring is either too fhort 
to admit of the requifite number of turns to correfpond to 
the fufee, or too wi eak to actuate the works for the whole 
time of gol , the dimenfions of that fpri ing will not sae 
the e veqquite conditions, and mult be hanged for 
more fuitable dimentfions. ‘The relative forces of the tone 
and when nearly relaxed, mult alfo be af- 
i by weights fufpended by the gut or chain, o rat is, 
ound cou the exterior furface of the barrel; for on the 
ratio of thefe extreme weights, or oe depend not only 
ye oe i iets © 3 of the fufee, but 
po fed are i: that ae no a dependenc e on ma 
the ratio of the extreme powers of ye entcl coe ja 
is to be eon ; whereas an attention to the ratio in quef- 
tion is ondition in the conftruction, that it will appear 
prefen tly 0 wht not to’ be difpenfed with, particularly 
when the w sane fhip profeffes to be of a fuperior kind. 
Conceiving now the main-{pring coiled up in 
end 
or — = ha to the fide o 
a. few times round the’ box; the outer end 
being at bers ten, fuppofing the fpring that is coiled 
Oo. a, CO atively relaxed ftate, preffing againft the 
Seen ‘of és ee with an effort calculated to unwind 
itfelf, i in this cafe the central part of the box is not filled by 
ping off without. carrying the 
many times‘as there are folds oe 
to the exterior end of the oe ae ing, this {pring is thus 
the fixed arbor that holds its mterior end, 
$ are gradually brought up to fill the central part 
which fituation its intenfity is increafed, in 
confequene of its being moved rom its quiefcent pofition ;: 
mit now the gut.or chain arrel wiil retrograde 
ad aay on the folds again, while ie aude {pring is re- 
Vor. XV. 
linder, placed ae a Sane parallel to t 
the box, 
force it ae per zl =) ae 
EE, 
-laxing itfelf gradually by. a ‘cnontae 2 diminution Bs 
power, 8 again in its cia - pofition. Thus 
power of the pn ng, contained in the box, is always = 
pofed to pull back the vee x itfelf eee the hand, or any 
c to the chain, has pulled it round in 
been ut to bet w ound rou 
and made fait to its end, im fuch : a eas tha it tur ning the 
cylinder round on the pivots arbor, 
chain round it while it is eek from the bo 2x3 in this 
is wound up as a Te, Li being 
of 
its boss. and provided iis farce 
, or difciess Fee a quicl- 
cent point, the cylinder ia cca een wot nid be a proper fufee 
for the machine to be actuated ao 
plied; but we have faid that the force OE the maliciptng 
always varying as it vee es oe f, after it has been wound 
up to the centre o ; therefore the cylinder muft 
pore be fo changed into pane aces . zon - plece 
of aétion of the chai s furfa 2 fhall be r lefs 
diftant fom its axi “of “not on, as s the law of oe 
in 
of the ne frrall demand, : order that the 
force tranfited to.the train of wheel-work, and thr éugh 
it to — or pendulum m, may be invariable, or very 
eee fo. t is obvious, from this view of the fubjec, that 
the figure of the sie oe ae . the cylinder i in ave 
tion, as a -fufee, mutt 
either by aight ie ne e frultam et a fone or ie 
curves of fome order, boundi mg the ides of the faid firur 
and. that the sont of the chain’s action ‘hall oes "Fro om 
the axis of the fufee’s mot! ‘on, as it revolves, in fuch a ways 
while the Bare of the main-{pring is diminifhed By its res 
laxation, -or soe aes from the centre of it its box xy that the 
pr oduct aie ‘from the force. of t ied 
e acting radius of ‘the fufec, fhail Aa in every ty uation the 
fnune ; for then the face pow er of the main-[pring, as it 
regards the train, will be invariable. It can ae be eX- 
pected. that the ofan can. determine the exact he 
eae are La his fufee, by any mat ae 
rule that may be -laid down from the meafurement of the 
{pring’s. aa ae Powers; ee for the fake of illuftrating the 
theory of a-fufee’s ation more particularly, we wil prefent 
‘the reader with fome rules and calculations 
> Benj. M 
in all-c 
De 
Cy 
e foe of the curve, 
which will ee es ee ficies = the Fale, au ar evoluti ion 
Be ee 
clo * or watch is. ie or the main-fpring per ee 3 
the point where it lies isa the {pring is wound up: from 
the ia an fall the a ulars B A and 
pectively to ne axis A L, in which perpendiculars 
meee | let there be taken A Ea a H I proportional ¢ 
the refpective forces of ‘the main-fpring, when ating by the 
chain at t the aes of extret me power Band D; ‘through 
ai way 3 
£9 
ought always to wee uniformly rie fame, and as this force is 
3 U 
