QUEST FOR PERFECT TIMEPIECE (Continued from page 127) "So you want to get married, eh?" "That's find I'm glad to hear it. But you Itnow, Tom, just wanting to get married is not enough to justify an increase in salary. "Study your work — learn to know more about it than the other men in your department — and you von't have to come to me for an increase in salary. "Why don't you take up a home study course with the International Corrcj^pondence Schools? It's been the making of other men around here." Employers In every line of buslni'ss arc bccplnp for men who want to rvX abend and are willlnK to prove it by tialnlritf themselves to do stmic one thing well. One hnur a day of I. C. S. study «fll jireparo you fof the jxjsition you want In the work you like best. Mail the Coupon for Free Booklet INTERNATIONAL CORRESPONDENCE SCHOOLS "The lnUtT9Qi Vniversitu" Box 7700- F, Scranton, Pa. Without cost or oblication, please send me a copv of your booklet, *'Who Wins and why," and full partlculara about the subject before which I have marked X: TECHNICAL AND INDUSTRIAL COURSES HBrldKe EuKlneer DAutoiniihllc Wnrk Jl'lumblng D Steam Fltttnn 3 lleatlnff □ Ventilation □ Sanitary En^rineer J Sheet Metal Worker J Steam Knglneer □ Marine Engineer Dltifriijeratlon □ It. n. Locomotlres ]Air Brakes □ Train Or>eratlon □ it. It. Section Foreman □ a. U. Itiidge andltuildlns Foreman □ Chemistry □Pharmacy BCoal Mining Knglneer NavlKiitinn □ Agriculture t] Textile Overseer er Supt Surveying and Mapplnf? H Cotton Manufacturing jOns KnKines nToclraaber [] Woolen Mnnufacturtng □ nipsel Entrines [ ] Fruit Growing GUadio □ATiaUon Engines Lll'uuitry Farming BUSINESS TRAINING COURSES □ Architect Arcldtectural Draftsman ituilding Estimating Wood Mlllworklng Concrete liuihicr Contractor and Builder Structural Draftsman Structural Engineer Electrical Entjlneer Electric Wiring Electric Llchtinii Welding. Electric andQaa Tflecraph Enplneer Telephone Work Mechanical Enclneer Mechanical Draftsman Patternmaker □Madilntst Reading Shop Blueprints Civil Engineer Highway Eniiineerlng QBusIness ManaRement P Industrial Management □ I'ersonnel Management □ Traffic Management □ Accountancy □ Cost Accountant □ C. P. Accountant □ Bookkeeping □ Secretarial Work □ Spanish □French n Salesmanship DAdverllsinB Kame Street AddresL City DRusfnesa Correspontlcnce ir.ettering Show Cards Dsienography and Typing JCVraplete Commercial JKnnlish DSiiins JCivll Service iBallway Mall Clerk ]Mali Carrier JOrade School Subjects . High School Subjects _J Illustrating □ Cartoonlnc □ Lumber Dealer ..State.. Occupation // you reside in Canada, send /fti* coupon to tjie International Correeptindmee Schools Canadian, Limtti Montr eat, Canada ^rom EACHBIade The Muler-HiJiip putt a hair-Kpllttlnn edif^ on the dullo!<t wiifrty razor b1««le 100 ahavcs per blmdc. W. V. Walnh. Windnor, Ontario yame blade daily, 8 montlis. Honing g'wvn barbers thoQiiandit of tiniooth vhaveB from a Fin- Ifle KtraiK^it rdice blade. Ontv honing can put a NEW ^dse on a oafrty razor blade. Thin patentnl. acruraUla tftfl- rd hon«, made of vxtra-fine abraaivr, makm nch 10c blnde icive SI to t2 worth of Borvicr. Alfo bonrn utralffbl-
- -dKi' razors. M()NKY RKFUNDt^ if
not DFl.UJHTKU. VAITDC UDUC We will Bfnd yoti a lUUKO rRtt Mai.Ier-Hom-abB(». lulrly f re.- WITH FIRST ORDER of 12 f..r 93; or n«nd Wh.- for 1 or SI for 3. POSTPAID. Or vom may n^nd no mon- eyand ptiwpoftman jplM»vomtairhargt» . But SKND TODAY. WISCONSIN ABRASIVE CO. Dept. 6139 Station A Mitwaiike*. Wis. aves nit up to $30.00 a (lay. .Mr. Xur sold 4(1 at rumn hour. K. Blos- som sold 1(100 one wi'vk from window. Xcarly all of the trcmcndou.'; effort expended to reach present-day perfection has centered on dcvelopinp the escapement. This consists of the balance wheel, its hairspring, and the pallet. One forked end of the pallet enpaKes the openly spaced teeth of the last wheel in the train, called the escape wheel, and the other end encages w'ith a tiny jewel fitted to the hub of the balance wheel to give it the necessary back-and-forth impulses. A list of the men w-ho developed new watch escapements in the past century or two would be as long as your arm. It seemed simple enough to design a sort of ratchet arrangement that would make the balance wheel swing back and forth and thus per- mit the gears in the watch to turn at a slow and steady rate. The rub came in try- ing to do this in such a way that the bal- ance wheel could swing back and forth freely like a pendulum without having the mechan- ism interfere with its beating. The modern watch escapement is a refine- ment of a so-called lever escapement worked out by Thomas Mudge, English horologcr, more than 100 years ago. Mudge "s lever escapement- and Earnshaw's split balance wheel made the modern preci.';ion watch a possibility. Until clinvar was discovered, there had been no basic improvement in watches. In theory, the thin, ultra-modern watch of the last few years is exactly like the heavy, biscuitlike timepiece your grand- father carried. IF THE early watch experts had realized the magnitude of the task before them, they would, perhaps, have given up in despair. The effect of temperature seemed the great- est problem to solve. Yet its partial solution showed the watchmakers that there were other difficulties that applied to portable time- pieces and not to stationary clocks. That point in the development of timekeeping machinery marked the parting of the ways for watchmakers and clockmakcrs. From then on each group's methods of tackling troubles became totally different. The clockmaker, when he found that a certain condition was causing his clock to err, let the clock alone and tried to rectify the condition. The watchmaker, on the other hand, accepted the condition and tried to make his watch compensate for it. Today's most accurate clocks are Galileo's pendulums refined to the utmost and oper- ated under conditions that do not vary a hair's breadth from year to year. Mounted on huge concrete bases to elim- inate vibration, kept in rooms where the temperature and even the humidity and air pressure never are allowed to change, watched over by experts, it is small wonder that they give an excellent account of them- selves. Such clocks run with an error of only two-hundredth of one second a day — some even with less. The poor pocket watch is subject to chang- ing temperature, vibration, changing posi- tion, and other handicaps. Hence, no pocket watch could ever rival the best clocks for timekeeping. Yet, in view of the conditions under which a high-grade watch must oper- ate, its performance is a tribute to man's skill in building precision machinery. A really first-dass watch will frequently keep time within half a minute a month; and some- times, for long stretches, it will do even better. Aside from the effects of temperature, there are two other important causes of timekeeping error. One of these is the chang- ing tension of the main spring as it runs down. This defect w-as recognized by the early watch experts, and they worked out an elaborate and cumbersome system to correct it. If your great-grandfather owned a really fine pocket timepiece, it doubtless had in it a tiny gold chain that was vound into spirally arranged grooves in a wheel. This chain transmitted the power of the main spring to the first gear in the train and, as the spring ran down, the chain rolled off a higher and higher groove, thus changing the leverage with which the spring's power was supplied. This queer contraption was called the fusee. It is no longer used. Instead, watchmakers now make the main spring longer and taper it in such a way that there Ls relatively little difference in its strength for a twenty-four-hour run. Then they adjust the balance so that a slight change in the length of the swing will not change the timing of the swing. This is called the isochronism adjustment. Because it neither is absolutely perfect nor holds good beyond a twenty-four-hour run, it is advisable to wind a watch at exactly the same hour each day. The other important source of watch error is changing its position. Ordinarily, a watch may be placed in five different positions cither in your pocket or on your bureau. The normal position, with the winding stem up, is one, but it may tip over either way in your pocket, so that the stem points to right or left. That makes two more possible positions. Then you may place it on your bureau at night either face up or face down. That makes five positions in all. Since the balance wheel of a watch really is a form of pendulum, it is affected by gravity as well as by the tension of the hairspring. If it is not in absolute balance around the axis of its hub, the effect of gravity will be greater in one position than in another. A fine pocket watch, therefore, is adjusted for and tested in all five posi- tions. Here, too, a complete elimination of errors is not humanly possible. The United States Bureau of Standards, in testing watches of the railroad precision class, allows a toler- ance amounting to a difference in daily rate of five seconds between dial-up and dial- down positions. Thus, it is easily seen why a fine watch at all times should be car- ried in one definite position, preferably wind- ing stem up. If you want to go in for further refinements, hang it up at night. PALACE BURGLAR ALARM GUARDS CROWN JEWELS A NOVEL burglar alarm protects the Danish crown jewels, which can be seen by the public in the palace of Rosenborg at Copen- hagen. Should a person approach too closely the case of priceless jewels, an invisible alarm immediately sets off an ear-splitting outburst of bells and sirens. All doors to the chamber instantly close and lock automatically, and the cabinet containing the jewels sinks through a hole in the floor and disappears. Not gener- ally known, the existence of this alarm system was revealed only recently when an unwary guide with a party of tourists accidently set it off. kn attendant in the room drew his revolver and ordered everyone to stand where he was, while carloads of police rushed up and surrounded the castle. Explanations satisfied the police, and the tourists and their guide were allowed to go on their round of inspec- tion. 128 POPULAR SCIENCE MONTHLY
