Traditional Culture Encyclopedia - Weather forecast - What do 1 and 2 beside the Ou Man barometer mean?

What do 1 and 2 beside the Ou Man barometer mean?

1 and 2 on the side of Ou Man barometer stand for hand brake and foot brake respectively.

1 and 2 next to the Ou Man barometer are two independent pipeline systems, showing two barometers, one for hand braking and the other for foot braking. This is the design of the car.

Barometer is a tool and instrument, which is used to help judge possible weather changes and determine the rising height.