Show MEASURING WEATHER Many boys and girls and grown people peo-ple too for that matter do not understand un-derstand exactly what is meant by the terms high barometer and low barometer ba-rometer They do know In a general way that a high barometer Indicates fair weather and a low barometer styrmy weather so that It might be better lo say that they do not understand under-stand the reason for those indication i The whole matter may be made plain In a few words The barometer Is as Its Greek nnrnri Indicates a weight measurer but it la used only to m iaure the weight of the atmosphere It iu perhaps the most Important instriiment l employed In meteorology me-teorology arid Is of the greatest posrI ble value to sailors because it Indicates Indi-cates with unfailing accuracy the approach ap-proach of a stvrm How it docs this we have to explain Most of our young readers have seen one no doubt anti will remember that it consists of a glass tube to which Is attached a graduated scale Inside the tube Is a small column of mercury which rises from a cup of mercury at the bottom of the tube and the flg ireson the scale represent its varying height Now It Is easy to understand that as the mercury in the tube is connected with the mercury In the cup It will rise or fall in the tube as the pressure on the cup is Increased or diminished But the only pressure on the cup Is the weight of the atmosphere If therefore there-fore the atmosphere he relatively heavy hea-vy ihe mercury will rise in the tube If It be relatively light the mercury will fall In the tube Thus we learn two things by means of the barometer llrst that dry air Is heavier than damp air because the mercury rises In the tube In dry weather weath-er showing that greater pressure Is exerted ex-erted on the mercury In the cup and second that when the mecury falls In the tube stormy weather may be expected ex-pected because the air Is damp and light Tt would bo well for you to remember this difference between dry air and damp air for many persons have the mistaken Idea that damp air is heavy |