National Geographic : 1920 Jul
SUI M11CILY BUll WATCH The Waltham Scientific "Detachable Balance Staff" that Means So Much to You in Time-keeping Accuracy THE time-keeping accuracy of any watch depends absolutely upon the trueness (in the flat and round) of the Balance Wheel. This trueness depends largely upon the mechanical precision with which the Balance Staff is riveted to the Balance Wheel. SIn other words, if the Balance Staff is not firmly and truly located in its hub, the balance becomes eccentric or " wobbly in its action, S which immediately affects the time-keeping *, quality of the watch. -7L How important, then, is S this exclusive develop ment of the Waltham Scientific Detachable Balance Staff. Herein Waltham disregards the ordinary method of mak ing the Balance Staff act as both axle and hub to uard the wheel. The World's Finest Railroad Watch 23 jewels $79 and up You will note in the illustrations above that Waltham makes the Staff in two pieces. One a perfectly ground steel hub which is riveted to the Balance Wheel and is an integral part thereof. The Staff (you will note) has an accu rately ground tapered shoulder which permits of its being driven to its exact seat and located accurately to the ground steel hub. Any layman can understand that, if his watch is dropped or has a severe shock, the result will be a broken or bent Balance Staff, therefore requir ing repairs in this important unit. Now a Staff which can be withdrawn easily from the hub without affecting the original, perfect assembly of the Balance Wheel assures him of continued accurate time-keeping and service from his watch. On the other hand, when the ordinary Balance Staff is driven out of the Balance Arm for repair or replacement, the riveted part roughens and distorts the metal. Therefore, the original aperture in the Balance Arm has been more or less destroyed, and when the new Staff is fitted, the watch repairer must rivet over enough of the metal to secure the Staff, which distorts the Balance Arm and throws the Balance Wheel out of true and poise. The Waltham Scientific Balance Staff insures sim plicity of repair and the original time-keeping quality of your watch. This is yet another reason why your watch selec tion should be a Waltham. This story is continued in a beautifulbooklet in which you willfind a liberalwatch education. Sent free upon request. Waltham Watch Company, Waltham, Mass. WALTHAM THE WORLD'S WATCH OVER TIME "Mention The Geographic-It identifies you"