BOOK TWO
S u b jectTemperature
Adjusting
Continued ByС. T. Higginbotham
C o n su ltin g Sup erin tend en tSouth Bend
WatchCo.
C o m p lim en ts o f
South Bend Watch
Company
South Bend, Indiana
SHORT TALKS t o
WATCH MAKERS
BOOK T W O
SUBJECTT E M P E R A T U R Ę
A D J U S T I N G
( CONTINUED ) > BYС .
T.
HiGGINBOTHAM
CONSULTING SUPERINTENDENTS O U T H B E N D
W A T C H C O .
COMPLIMENTS OFS
o u t hB
e n dW
a t c hC
o m p a n ySOUTH BEND, INDIANA
C H A R L E S T. H IG G IN B O T H A M M r. H ig g in b o th a m p ro b a b ly has a m ore th o r- o ugh a n d b ro a d e r ехрегіеп се in th e science o f m a k in g h ig h g ra d e w atch es th a n a n y o th e r m an in th e U n ite d S ta te s . A lth o u g h sixty-five y e ars o f a g e , he ta k e s an a c tiv e p a r t in a ll m a tte rs t h a t c o n ce rn th e pro- d u c tio n o f a m o v em e n t t h a t is g a in in g a re p u ta - tio n as a m o st a c c u ra te a n d d u ra b le tim e p ie c e — th e S o u th B end.
/■ H E a d ju s tm e n t of w atch es is com m only Ё classed u n d e r th re e h e a d s : Isochronism ,
te m p e ra tu rę a n d positio n . S tric tly sp e a k in g th e first e m b ra ces th e o th e r tw o , b u t as co m m o n ly u n d e rsto o d it m eans sim p ly ad ju st- in g th e h a irs p rin g a n d b a la n ce to each o th e r so t h a t th e l a tte r shall p e rfo rm its long a n d sh o rt a rcs in th e sam e tim e w hile th e w a tch is in a h o rizo n tal positio n . T h en pósitio n a d ju s tm e n t steps in to eąu a liz e th e tim e o f v ib ra tio n fo r a ll th e o th e r p ositions. F in a lly te m p e ra tu rę a d ju s t m e n t p ro d u ces a u n ifo rm ity in th e tim e o f th e v ib ratio n s in h e a t a n d cold. T his a d ju s tm e n t is e n tire ly d is tin c t fro m th e o th e r tw o so f a r as th e m ean s u sed to secu re i t a re co n cern ed . I t is of th is a d ju s tm e n t t h a t th e p re s e n t a rtic le tre a ts . B efo re a tte m p tin g it, th e s tru c tu re , p ro p e rties a n d a c tio n of th e b a la n ce should be c a re fu lly stu d ied .
S T R U C T U R E . T h e ch ro n o m eter, or m ore p ro p e rly sp e a k in g , co m p en satio n b a la n ce is com posed o f tw o m e ta ls ; brass an d steel. T h e arm s a re o f s te e l; th e rim o f steel a n d brass la m in a te d ; th e inside ste el, th e outside brass. T h e p ro p o rtio n a l ex p an sio n of m eta ls, as has been ex p la in ed in b o o k one, is c alled th e coefficient of e xpansion. B rass, b e in g a n a llo y , its coefficient o f ex p an sio n varies a c c o rd in g to th e p ro p o rtio n o f th e d iffere n t m eta ls com pos- in g th e a llo y . Zinc has a b o u t th re e tim es g r e a te r coefficient o f ex p an sio n th a n ste el, con- s e ą u e n tly , th e la rg e r th e p e r c e n t. o f zinc th e g r e a te r th e ex p an sio n . B rass u sed in b ala n ce s has its co m p o n en t m eta ls so p ro p o rtio n e d th a t it is c ap a b le o f b ein g b ro u g h t to a v e ry h a rd
d itio n an d still possess a b o u t tw ice th e coefficient of e x p an sio n o f steel.
I f w e secure to g e th e r a strip o f brass a n d a strip o f ste e l, a n d su b m it it to h e a t or c o ld , th e brass e x p an d in g or c o n tra c tin g m ore th a n th e steel, w ill cause th e b a r to d e fle c t as show n b y
F u j. 1 .
в
th e b ro k e n lines in F ig . 1. S h o u ld e ith e r m e ta l be to o g r e a tly in excess o f th e o th e r no deflectio n will ta k e p lace. T h e m e ta l h a v in g th e g r e a te r m ass w ill co m p le te ly о ѵ е гс о т е th e o th e r c a rry
-F i< j. 2 .
<
__________________________________ I
i ... ~ 1 . : с in g it fo rw a rd in a d ire c t line ju s t as th o u g h th e b a r w as com posed o f a single m eta l. S ee F ig . 2. I t follow s th e n t h a t in o rd e r to secu re th e b e st actio n in th e rim th e m eta ls m u st b e a r a c e rta in p ro p o rtio n to e ac h o th e r in dim en sio n a n d also in d e n s ity an d s tru c tu re . T h e p ro p e r pro p o r- tio n s a re % steel % brass. T his is to sa y , th e se ctio n al a re a o f th e rim should show th e s e pro- portio n s.
T h e com bined th ic k n e ss o f th e rim o f an 18s b a la n ce should be a b o u t 127 h u n d re d th s o f a m illim eter.
4
P R O P E R T I E S . T h e less th e th ic k n e ss o f th e rim th e m ore a c tiv e ; w hich is to say th e g r e a te r its d e fle ctio n ; b u t if it is m ad e to o th in i t w ould be deflected b y cen- trific a l fo rc e — th e te n d e n c y o f m e ta ls to fly from th e c e n te r w hen in c irc u la r m o tio n —w hen th e b a la n ce is in ra p id m o tio n a n d th e tim e k e e p in g ą u a litie s o f th e w a tc h b e m ore o r less im p aired . T h e jo in t b e tw ee n th e m eta ls m u st be p e rfe c t. B low holes a re f a ta l to u n ifo rm a ctio n . F o r th is reason th e old m eth o d o f so ld e rin g th e tw o
m eta ls to g e th e r w ith silver solder h as been su p e rced ed b y m a k in g a sm elted jo in t. T he m eta ls m u st be o f u n ifo rm th ick n ess an d te m p e r th ro u g h o u t; o therw ise th e d eflection o f b o th sections o f th e rim w ill n o t be u n ifo rm w ith th e re su lt t h a t deflectio n from h e a t or
5
cold w ould th ro w th e b a la n ce o u t o f poise. S ee F ig . 3. In th is case th e brass a n d ste el a re c o rre c tly p ro p o rtio n e d a t one side w hich w ould o f course p ro d u c e th e p ro p e r d e flectio n , w hile a t th e o th e r side th e ste el is g r e a tly in excess of th e b rass fo r th e g r e a te r p o rtio n o f its le n g th w ith a re s u lt t h a t th e d e flectio n o f th e rim a t t h a t side w ould be slig h t as c o m p ared w ith th e o p p o site side.
A C T I O N .—T h e a ctio n o f h e a t e x p an d s th e m eta ls o f w hich th e b a la n c e is com - posed. T h e a rm e lo n g a te s, th ro w in g t h a t p a r t o f th e rim to w hich i t is a tta c h e d o u t fro m th e c e n te r. T h e rim also e lo n g a te s b u t th e b rass o n th e ou tsid e e x p an d in g m ore th a n th e ste el on th e in sid e causes it to cu rv e in w a rd ly ; th is cu rv a tu re in cre asin g fro m th e a rm to th e c u t.
F ig . 4 w ill illu s tra te ju s t how th is c u rv a tu re ta k e s p lace. T h e fu li lines show th e n o rm al
c o n d itio n o f th e b a la n c e ; th e b ro k e n lines fhe effect o f h e a t. I t should be u n d e rsto o d t h a t in th is d ra w in g , as in th e p re ce ed in g ones, th e effects illu s tra te d a re so m ew h at e x a g e ra te d , w hich is n ecessary in o rd e r to show th e actio n c le a rły . I t w ill be seen b y re fe re n ce to F ig . 4 t h a t u n d e r th e influence o f h e a t th e rim recedes fro m th e c e n te r a t A , a p p ro ac h in g th e c e n te r to a m uch g r e a te r e x te n t a t B, w hile a t С it m ain- ta in s a u n ifo rm d istan c e .
T o fu lly u n d e rsta n d th e c o n d itio n s d esc rib ed ab o v e it is w ell to s tu d y th is d ra w in g , F ig . 4, c a re fu lly . I f a ll th e m e ta l e m b ra ce d b y th e b a lan ce w ere c o n c e n tra te d a t A th e re su lt w ould be t h a t it w ould reced e from th e c e n te r w hen h e a te d an d a p p ro ac h th e c e n te r w hen cooled, w hile if it w ere c o n c e n tra te d a t В th e o pposite c o n d itio n w ould b e p ro d u c ed , w hich is to say , it w ould a p p ro ac h th e c e n te r w h en h e a te d a n d re ce d e fro m i t w hen cooled. N ow if a ll th e m e ta l w ere c o n c e n tra te d a t С i t w ould m ain ta in e x a c tly th e sam e d ista n c e fro m th e c e n te r w h e th e r h e a te d o r cooled. T his fe a tu re is‘ta k e n a d v a n ta g e o f to secu re a d ju s tm e n t to te m p e ra tu rę . T his a d ju s tm e n t is c alle d “ C o m p en satio n ” b y w hich n am e it w ill be re fe rre d to in th is a rtic le in fu tu rę . 1 d e sire h e re to cali a tte n tio n to a p e cu liar c o n d itio n p ro d u c e d b y th e deflectio n o f a la m in a te d b a la n c e r i m : —A C U T C O M P E N - S A T IO N B A L A N C E C A N O N L Y B E A B S O - L U L E L Y T R U E IN O N E T E M P E R A T U R Ę . T his can be re a d ily u n d e rsto o d b y re fe re n c e to F ig . 4.
7
Position of screws.
G
O M P E N S A T IO N b alan ces a re p ro v id ed w ith se v e ra l m o re holes in th e rim th a n a re n e ed e d fo r th e screw s used. T his is d o n e to afford m eans fo r c h an g in g th e position o f th e screw s in o rd e r to effect c o m p en sa tio n . F o r сопѵепіепсе o f re fe re n c e w e sh all n u m b er th e holes a t e ac h side o f th e b a la n ce b eg in n in g a t th e a rm w ith n u m b er 1.screw s in th e rim . H o le s 1 to 9 inclusive hołd screw s, w hile 10 to 13 inclusive a re v a c a n t. T his c o n d itio n w e c a l i :— “ A li screw s b a c k .” In F ig . 6, w hich has th e sam e n u m b e r o f holes,
2 to 5 inclusive a re v a c a n t, w hile 1 a n d 6 to 13
inclusive h o łd screw s. T his is c a lle d :— “ A li screw s fo rw a rd .’’ H o le s 1 a n d 7 гесеіѵе th e
m e a n tim e screw s, w hich a re пеѵег ch an g e d to o th e r holes.
W e shall ta k e tw o w atch es w ith b alan ces screw ed u p e x a c tły as show n in F ig s. 5 a n d 6. T h ese a re tw o re g u la r S o u th B en d W atc h e s w ith th e b alan ces sim p ly screw ed u p fo r th is p a rtic - u la r te s t. W e shall giv e th e ra te s a n d erro rs w ith th e screw s in p o sitio n as show n in F igs. 5
a n d 6, a n d also th e ra te s a n d e rro rs show n b y c e rta in c h an g es in p o sitio n o f th e screw s. L e t i t be u n d e rsto o d t h a t w hen we sa y , fo r in s ta n c e : M ove No. 9 to No. 10 it m eans t h a t a p a ir of screw s a re to be m o v ed ; th is is to sa y N os. 9 a t op p o site side o f th e rim . I t w ill be observed t h a t F ig . 6 shows b u t h a lf a b a la n ce . This m e th o d is fo r eco n o m y o f space an d w ill be used in all su b seq u e n t d raw in g s.
T h e stu d e n t h av in g e q u ip p e d h im self w ith te m p e ra tu rę c ab in e ts should m ak e tria ls o f sev- e ra l w atch es fo r th e sa k e o f p ra c tic e in tim in g b efo re a tte m p tin g a d ju s tm e n t. F o r th is p u r- pose h e should ru le a few r a te p ap ers. T hese a re p a p ers c o n v e n ien tly ru led fo r k e e p in g reco rd s o f w atch es u n d e r tr ia l ; th o se illu s tra te d
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in F ig . 7A an d 7B w ill b e fo u n d c o n v e n ie n t fo r th is p u rp o se. T h e first colum n to th e le f t is fo r th e d a t e ; th e n e x t fo r t h e tim e w hen com parison w as m a d e ; th e n e x t fo r th e d ifferen ce in tim e b e tw ee n th e w a tch a n d th e c lo c k or o th e r s ta n d a rd o f co m p a ris o n ; th e n e x t fo r th e g a in or loss as c o m p a red w ith th e p rev io u s c o m p a ris o n ; th e co lu m n a t th e r ig h t fo r th e te m p e ra tu rę e rro r. T h e te m p e ra tu rę a t w hich th e w a tch w as ru n or o th e r m a tte r m a y also be in se rte d in th is co lu m n if d esired . W e also enclose in th e b o o k le t a sam ple r a te p a p e r as u sed in th e a d ju s tin g d e p a rtm e n t o f th e S o u th B end W a tc h C o m p an y . T his p a p e r is v e ry e la stic in ІЦ p o ssibilities. I t can be u sed fo r iso ch ro n al, te m p e ra tu rę a n d p o sitio n ad ju s tm e n ts as w ell as or m an y o th e r k in d s o f ra te s.
Rules to be observed in
trials.
^ " y E E t h a t th e w a tc h is in p e rfe c t o rd e r; c le an a n d fres h ly oiled. I f th e oil is * a t a ll th ic k o r viscid th e cold te m p e ra tu r ę w ill m a k e i t m o re g lu te n o u s a n d r e ta r d th e m o tio n o f th e b a la n ce .
B e sure t h a t th e b a la n c e h as a sufficient a m o u n t o f e n d sh a k e. T h e p la te a n d c o ck , b ein g com posed o f brass o r n ick e l, c o n tra c t m ore in th e cold th a n th e staff a n d as a co n seq u en ce m ay re ta r d th e m o tio n o f th e b a la n c e if th e e n d sh a k e is to o close.
A lw ay s ta k e th e tim e w hen th e second h a n d o f th e w a tc h is a t 60 re g ard less o f w h e re th e second h a n d o f th e clo ck m a y be. T his fo r tw o re a s o n s :— F ir s t, should th e re be a n y e r ro r in th e
12
sp acin g o r in th e c e n te rin g o f th e d ia l it w ould th u s be e lim in a te d so f a r as a n y d ilfe re n c e w hen th e co m p ariso n w as ta k e n . S eco n d , it lessens th e lia b ility o f m is ta k e s in tim in g as w ill becom e a p p a re n t la te r on.
In tim in g , c a rry th e tic k o f th e clo c k or c h ro n o m e te r m e n ta lly , k e e p in g th e gaze ste a d ily fixed on th e w a tch . A m a rin ę c h ro n o m e te r is e x c e lle n t to use as a tim e r fo r th e reaso n th a t it b e a ts h a lf seconds, b u t a little p ra c tic e w ill e n a b le a n y o n e to e stim a te h a lf seconds v e ry clo sely fro m a c lo c k b e a tin g seconds. P ra c tic e c o u n tin g first. B e g in n in g w hen th e second h an d o f th e clo ck is a t 60, sa y , h a lf— o n e —h a lf—tw o —h a lf—th r e e —h a lf — fo u r — h a lf —five— an d so on. In tim in g w atch es b e g in to c o u n t w hen th e h a n d o f th e w a tc h is a p p ro a c h in g th e 60, an d a b o u t 10 to 15 seconds fro m it. L e t us assum e t h a t th e h a n d o f th e w a tch b e in g tim e d is a p p ro ac h in g th e 60 an d th e h a n d o f th e clock a p p ro ac h in g th e 30 w h en th e c o u n t is begun. W e b e g in :—F iv e — h a lf —six— h a lf—seven— h a lf —e ig h t—h a lf —n in e— h a lf—t h ir ty — h a l f — one— h a lf—tw o — h a lf —. A t th is m o m en t th e second h a n d o f th e w a tch re ac h es th e 60. I t follow s th e n t h a t th e w a tch is e ith e r 32k> seconds slow or th e difference b e tw ee n t h a t an d 60 w hich is 2 7 ^ , fa st. A g lan c e a t th e m in u tę hands w ill d e te rm in e w h e th e r i t is fa s t o r s lo w ; it w ill also d e te rm in e th e n u m b er o f m in u te s it is o u t in case it should be one or m ore.
R u n th e w a tch b o th in h ig h and Iow tem - p e ra tu re s in a h o rizo n tal positio n w ith th e d ial up. T h e re a re tw o reasons fo r t h i s :— I t is easily co m p ared w ith o u t d is tu rb in g ; b u t m ore im -
13
p o r ta n t still it avoids th e in tro d u c tio n o f a n y p o sitio n e rro rs th a t m ig h t ex ist in th e w a tch .
T h e w a tch m a y b e run in its ow n case or it m a y be ru n in a n y close sh u ttin g re c e p ta c le w hich w hile n o t n ecessarily a ir tig h t shoidd a t le a s t p re v e n t th e fre e ingress o f air.
R u n th e w a tch fo r 24 ho u rs in e ac h tr ia l, tim in g it as n e a rly a t sam e h o u r as possible. A few m in u tes e a rlie r or la te r w ill m a k e no differ- en ce b u t should th e re be a g r e a te r a m o u n t it m ig h t, in w hich case it is b e tte r to re p e a t th e tria l.
R u n th e w a tch in th e h ig h te m p e ra tu rę first; th e n , a fte r tim in g , w ind it b u t do n o t se t it. I t is b e st n o t to ru n th e risk o f d istu rb in g th e ra te b y se ttin g b e tw ee n th e tria ls. T h e difference in tim e w ill show th e v a ria tio n .
A fte r rem o v in g fro m th e cold c a b in e t do n o t open th e re c e p ta c le or case c o n ta in in g i t fo r a t le a st an h o u r. T his giv es it tim e to a tta in th e te m p e ra tu rę o f th e a ir in th e room w hich is n ecessary as a p re v e n ta tiv e fro m ru st. I f th e w a tch should be open ed im m e d ia te ly u pon bein g rem o v ed from th e cold c a b in e t i t w ould “ sw ea t” as i t is c a lle d ; t h a t is, th e m o istu re fro m th e a ir w ould condense u p o n th e ste el p a rts a n d possibly pro d u ce rust.
Figuring rates and making
alterations.
I
N m a k in g o u t ra te s w e g e n e ra lly use signs an d a b b rev iatio n s in o rd e r to econom ize space an d to save tim e . T h e plus sign is u sed to sig n ify w hen th e w a tch is fa s t o f th e clo ck an d th e m inus sign to in d ic a te w hen it is14
slow. T h e plus sign m a y also be u sed to in d ic a te w h a t is te rm e d over co m p en satio n a n d th e m inus sign to in d ic a te u n d e r compensation-. A w a tch w ith th e b a la n ce m ad e o f a single m e ta l a n d h av in g a ste el h a irs p rin g w ill, if re g u la te d in m ean te m p e ra tu rę , g a in in th e cold a c d lose in th e h e a t. T h is w e c ali u n d e r co m p en satio n . W h en a w a tch g a in s in th e h e a t a n d loses in th e cold w e sa y it is over c o m p e n satio n .
A n im p o rta n t ru le to be o bserved in fig u rin g ra te s i s : —W h en th e signs in d ic a tin g th e co ld a n d th e h e a t ra te a re a lik e s u b tra c t th e lesser fro m th e g r e a te r ; th e re m a in d e r is th e e rro r. W h en th e signs a re opp o site a d d th e tw o to g e th e r a n d th e sum w ill be th e e rro r. A w a tc h ru n n in g in b o th te rm p e ra tu re s on a fa s t r a te b u t fa s te r in th e cold is o f course u n d e r co m p en sa tio n b ecau se if t h a t w a tch , h a v in g g a in e d , say, 15 seconds in th e cold a n d 5 seconds in th e h e a t, h a d b een re g u la te d so as to g a in 5 seconds in th e cold i t w ould, o f co u rse, h a v e lo st 5 in th e h e a t. A w a tc h th e re fo re g a in in g m ore in th e co ld th a n in th e h e a t is u n d e r co m p e n sa tio n ; g a in in g less in th e cold th a n in th e h e a t is o v e r c o m p e n s a tio n ; losing m ore in th e h e a t th a n in th e cold is u n d e r c o m p e n sa tio n ; losing m ore in th e cold th a n in th e h e a t is over co m p en satio n .
Moving the screws.
ц 'tę I I E N a w a tch is u n d e r co m p en satio n ^ / one or m ore o f th e screw s should b em oved fo rw a rd as in d ic a te d on F ig . 8 w h ere th e d o tte d lin e u n d e r N o. 9 shows t h a t th e screw has b een m oved fo rw a rd to N o. 10.
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W h en th e w a tc h is o v er c o m p en sa tio n one or m o re screw s should be m oved b a c k as show n on F ig . 9. M oving a screw fo rw a rd or b a c k on a rim a c e rta in d istan c e does n o t a lw ay s p ro d u ce th e sam e re su lt. T h e re a re m a n y causes fo r y a ria tio n , one o f w hich I d esire to cali p a rtic u la r
th e rim as illu s tra te d in F ig . 4. I t w ill be re a d ily seen t h a t a lim ite d m o y em en t fo rw a rd or b a c k a t С w ou ld p ro d u ce little o r no c h a n g e in co m p en satio n as c o m p a red w ith th e sam e a m o u n t o f m o y em e n t a t В fo r th e reaso n th a t th e p a r t of th e rim a t С c h an g es its d istan c e fro m th e c e n te r o f th e b a la n c e v e ry s lig h tly ,'if a t all.
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R ate papers
■ ł T G . 7A is a r a te p a p e r g iy in g 8 suppo- I - I sititio u s tria ls of w atch es in w hich th e
r ra te s w id e ly differ a lth o u g h th e e rro rs a re a lik e . L e t th e s tu d e n t stu d y th is p a p e r c a re fu lly a n d m a k e h im self fa m ilia r w ith th e m eth o d used. W h en he h as c o m p le te ly m aste red it he w ill b e a b le to m a k e o u t a n y r a te t h a t m a y be p re se n te d . T h e tria ls a re sup p o sed to be of 24 h ours d u ra tio n each . T h e first b e in g in high te m p e ra tu rę and th e second in Iow, w hich we w ill re fe r to as h e a t a n d cold. T h e w a tc h w as w ound b u t n o t se t b e tw ee n th e tria ls .
In th e first tr ia l th e w a tch w as se t e x a c t an d was p lac ed in th e h e a t. W h en ta k e n o u t i t w as 14 seconds slow. I t w as p lac ed in th e cold w ith o u t re s e ttin g a n d w h en ta k e n o u t w as still 14 seconds slow, n o t h a y in g y a rie d d u rin g th e tr ia l. R e fe rrin g to c o lam n 4 w e h a y e c a rrie d o u t fo r th e h e a t tr ia l, m inus 14, fo r th e cold tr ia l, 00. T h e loss b e in g in th e h e a t w e h ave m a rk e d it, U n d . 14. In th e second tr ia l i t d id n o t v a ry in th e h e a t b u t g a in e d 14 seconds in th e cold w hich we find m a rk e d , plus 14, in th e 4 th colum n. T his w a tc h w as also, U n d . 14. In th e th ird tr ia l th e w a tch lost 7 seconds in th e h e a t a n d w hen ta k e n fro m th e cold w as fo u n d to be c o rre c t, it h a v in g g a in e d th e 7 seconds, w hich it h a d lo st p re y io u sly , c o n se ą u e n tly th e 4th colum n is c a rrie d o u t, m inus 7 a n d plus 7 m ak - in g 14. In th e 4 th tr ia l t h e w a tch lost 3 seconds in th e h e a t an d w as fo u n d to be 8 fa st w hen ta k e n fro m th e cold, it h a y in g g a in e d , n o t o n ly th e 8 seconds, b u t also th e 3 seconds it h a s lo st
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p re v io u sly , m a k in g a g a in o f 11 seconds. In th e 4 th colum n i t is c a rrie d o u t, m inus 3 an d plus 11, m a k in g 14. In th e 5 th tr ia ! th e w a tch g a in e d 3 seconds in th e h e a t a n d w as fa s t 20 in th e co ld h a v in g g a in e d th e d ilfe re n c e , 17 seconds. T h e 4 th co lu m n is c a rrie d o u t, plus 3 an d plus
17, s u b tra c tin g 3 fro m 17 leav es 14 a n d as th e g r e a te s t g a in w as in th e cold it is u n d e r 14. In th e 6th tr ia l th e w a tch w as .5 (fiv e-ten th s') sec onds fa s t w hen p lac ed in th e h e a t ; w hen ta k e n o u t i t w as 4 seconds fa s t, h a v in g g a in e d 3.5. W h en ta k e n fro m th e cold it w as 21.5 ; a g a in of 17.5; th e d ifferen ce b ein g U n d . 14. In th e 7th t r ia l th e w a tch w as slow 1.5 w hen p lac e d in th e h e a t a n d fa s t 1.5 w hen ta k e n o u t w hich w as c a rrie d o u t plus 3 in colum n 4. I t w as 18.5 w hen ta k e n fro m th e cold, th e d ilfe ren c e , plus 17 b e in g c a rrie d o u t in colum n 4. T h ese ra te s s u b tra c te d Іеаѵе U n d . 14. In tr ia l 8 th e w a tc h w as fa s t 1 second w hen p lac e d in th e h e a t a n d c o rre c t w hen ta k e n o u t, h a y in g lost 1 second, c a rrie d o u t m inus 1. I t w as 13 seconds fa s t w hen ta k e n fro m th e cold. T hese tw o a d d e d m a k e U n d . 14.
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F ig . 7 В is a r a te p a p e r m a d e fro m a c tu a l te s ts o f S o u th B end fu li p la te w a tch N o. 542831. In 24 h o u r tria ls , th e te m p e ra tu re s b e in g 90 a n d 40, d e g ree s F ., th e b a la n ce b e in g screw ed u p as, show n in F ig . 5. In th e first tr ia l i t w as set c o rre c t. W h en ta k e n fro m th e h e a t it w as slow 9 seconds. W h en ta k e n fro m th e co ld it w as fa s t 28 seconds. A d d in g 9 an d 28 g ives 37, th e a m o u n t it g a in e d in th e cold. A d d in g 9 a n d 37 we h av e its e rro r, 46 seconds an d as it lost in
th e h e a t an d g a in e d in th e cold it w as u n d e r c o m p e n sa tio n . T h e 9th screw w as m oved to n u m b er 10 as show n in F ig . 8, th is re d u ce d th e e rro r to 43.5, a m o u n tin g to 2.5 seconds. I t w ill n o t be n ecessary to ех р іаіп in d e ta il a ll th e tria ls w hich follow b u t it is d e sirab le to cali a tte n tio n to th e v a ry in g effect p ro d u ced b y m oving th e screw s on d iffere n t p a rts o f th e rim . M oving fro m 9 to 10, as has b een seen m ad e a d ilferen c e o f 2.5 seco n d s; 10 to 11, o f 3.5 seco n d s; 11 to 12, o f 3 seconds; 12 to 13, o f 3 seconds. In m a k in g c h an g e s it is w ell to a void ju m p in g a screw оѵег 1 o r m ore o th e r screw s fo r th e reaso n t h a t it is lia b le to m ak e th e b a la n ce m ore
c u lt to poise fro m th e c h an g e o f w e ig h t. F o r th is reaso n i t is d e sirab le to гаоѵе th e screw s in seąu en ce as show n in th e a lte ra tio n b etw ee n th e 5 th a n d 6 th tria ls , w h ere 8 is m oved to 12, 6 to 10, 5 to 9 an d 4 to 6. T his a lte ra tio n m ade a differen ce o f 29.5 seconds re d u cin g th e e rro r to U n d . 4.5. M oving 3 to 4 m ad e a d ifferen ce of .5 only. T his s lig h t c h an g e w as oceasioned b y th e slig h t c u rv a tu re o f th e rim as illu s tra te d in F ig . 4. M oving fro m 4 to 5 a n d from 2 to 3 m ad e a d ifferen ce o f 4.5 seconds, b rin g in g th e w a tch fro m U nd. 4 to over .5. T his le ft th e screw s in th e p o sitio n show n in F ig . 11.
Variation in the position of
screws.
E S P I T E a ll th e c are t h a t it is possible to Д J use in th e m a n u fa c tu re o f b a la n ce s or th e sp rin g in g o f w atch e s no e n tire lo t w ill com e o u t th e sam e, a f te r co m p e n satio n , so f a r as th e p o sitio n o f th e screw s in th e b a la n ce a re co n cern ed . F ig . 6 shows a b a la n ce in w a tch n u m b er 542832 w ith a ll screw s fo rw a rd . I t show ed a c o m p e n sa tio n e rro r F frrc k ^ ^ s e c o n d s . M oving 6 to 4 re d u ce d it 3 seconds. M oving .4 to 3 as show n in F ig . 9 m ad e no ch an g e. F in a lly , w hen c o m p e n sa tio n w as secu red th e screw s o ccupied th e po sitio n show n in F ig . 10.
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