Open main menu

Page:Popular Science Monthly Volume 90.djvu/865

This page needs to be proofread.


Popular Science Monthly

��849

��Making Your Watch Tell the Whole Truth

THE average commercial traveler who journeys about the United States has to keep a close watch on his timepiece to see that it is telling the truth. There is an hour's difference in time when you enter and lea\e some cities and it's an im- portant matter that you do not forget to set your watch back or forward an hour, ac- cording to which way you are traveling. If you over- look it, you may miss a train.

An express official who travels almost all the time and is so busy that he sometimes forgets to change his watch at Detroit, Mich., for instance, or at Dodge City, la., has frequently had an experience of this kind. Sometimes he has arrived an hour ahead of time or, perhaps, an hour after a train has left, giving him time enough for reflection.

Recently, he conceived the idea of mak- ing his watch tell all four different times — Eastern, Central, Mountain and Pacific. He went to a jeweler and had extra hour hands put on his timepiece — each of a different color, so that he can recognize it at a glance, on the face of his watch. For instance, the ordinary hour-hand, set at Eastern time, is silver; a blue hand, set an hour back, represents central time; a red hand, for moun- tain time, is set two hours back; and a green hour hand, three hours back, represents Pacific time.

You can do this to your own watch. The jeweler will make a set of hands of these colors and alter your watch for a consideration of a few dollars, so that when you go traveling it will not be necessary to dis- turb the mechanism of your watch by setting the hour- hands back and forth frequent- ly, according to whether you are in De- troit, Chicago, New York, Denver, San Francisco, or other places on the map.

But such an arrangement would be parti- cularly useful only to the itinerant sales- man or other frequent traveler.

���The tests relate to ice consumption, temperature distribution, and air circulation within the refrigerators. Ekjuipment inside each refrigerator is connected with the galvanometer

How the War Department Tests Its Household Refrigerators

ACCORDING to the Bureau of Stand- . ards, the ordinar\- household refrig- erator, even of the best make, is by no means as effective in the saving of ice as might be desired. Before awarding contracts to supply the army with refrigerators, the War Department uses temperature-measur- ing instruments for testing each t\peoffered. Thedimensionsof therefrigeratorsare measured, as well as the tempera- tures inside and outside, the size or area of ice used, the amount melted per day, the amount of air circulating through the food chambers, and, finally, the heat transmission of the refrigerator walls.

The temperature measure- ments are made by means of thermocouples (instruments for noting differences in temjjerature by electricity), several of which are mount- ed inside each refrigerator and several others at various points outside. By this means all measurements are made with a single galvanometer (an instrument for measuring the intensity of an electrical cur- rent), shown on the tripod stand in the illustration. The lead wires from each of the thermocouples, some thirty in number, are connected succes- sively with the galvanometer by means of the simple switchboard on the table.

The temperature is measured in the air entrance and the air exit to the ice chamber.

���You can have addi- tional hands made for your watch so' that it will indicate the time of the locality you are in

�� �