Mercury barometer column height indicating-recording device - employs pointer under magnifying glass carried by element on parallel shaft

摘要

A mercury barometer with an index which slides on the tube to memorise position of height of the column suffers from scratching and dirt. A parallel support carrying a pointer overcomes this problem. The barometer comprises a tube (2) with a reservoir (3) contg. mercury attached to a support plate (1). A scale (4) graduated in millimetres is located alongside the tube to give barometric height. A sliding element (6) which slides on a shaft (7) parallel to the tube carries a magnifying glass (8) which covers a pointer (5). This enables the level (N) of the mercury column to be read against the pointer and graduations. A line (9) across the glass facilitates alignment with the mercury level.