Barograph

BAROGRAPH (from Greek baros meaning weight and grapho meaning write), a self-recording barometer. Mercury barographs (see Figure 1) are a siphon barometer whose lower knee is equipped with a float

Figure 1. Mercury barograph.

connected by a pulley transmission to a writing pen. The pen draws a continuous curve of barometric pressure on ruled paper for days and hours, placed on

Figure 2. Aneroid barograph.

a uniformly rotating drum. The drum's clockwork mechanism is wound for a whole week. Aneroid barographs (see Figure 2) are constructed on the model of the Vidi aneroid barometer (see Barometer). A metal airless box with elastic corrugated walls changes its volume depending on barometric pressure. A system of levers connects the box with the writing pen, which records the pressure existing at any given moment on paper. Barographs are very convenient for continuous observation of the course of atmospheric pressure over a long period of time. They are also used as recording altimeters in flights. Aneroid barographs are much more convenient than mercury barographs. Very good and accurate aneroid barographs are manufactured by the firm "Richard" in Paris.

N. Ignatov.