National Geographic : 1919 Feb
THE KIFNTI.M Pen & IALLYT BU LT FOREIGN WATCH Pendant andBow Patented Colonial A Extremely thin at no sacrifice of accuracy. 21 and 19 jewels $125 to $240 or more, depending upon the case SHE watch presents the same elements of Mystery that once surrounded the automo bile. Now, nearly every one knows some thing about a motor car's mechanism. It is to make the "works " of the watch an " open book" that these Waltham advertisements are i designed--to instruct and protect you in buying a I" watch. SThe mainspring is the power of a watch. It is a piece of spe cially hardened and tempered steel, about twenty inches long, coiled in a barrel between the upper and lower plates of the movement. It is subjected to varying conditions of service in temperature and tension. The variation in thickness of two one-thousandths of an inch, or lack of uniformity in hardening and tempering, will decide the time-keeping quality of your watch. The Waltham Watch Company produces fourteen tons of mainsprings every year. It is the largest mainspring maker in the world. The Waltham main spring is cut from long rolls of steel of uniform and special quality, then tempered in resilientform by a secret process, and is placed in the watch coiled into a hardened and tempered steel barrel. This is exclusively a Waltham practice. The foreign mainspring is not only cut in short lengths, but hardened and tempered in short lengths--therefore every foreign mainspring is an individual spring of uncertain temper, making the watch a liability. The foreign maker of watch movements buys his springs in the open market. That is one reason why the imported watch gives such varying service. An inferior mainspring means an inferior watch - no matter how much you pay for it. The uniform superiority of the Waltham mainspring is one of the reasons why the horological experts of the leading nations of five continents chose Waltham in preference to watches of any other make. WALTHAM THE WORLD'S WATCH OVER TIME "Mention the Geographic-It identifies you."