Device for measuring variations in ambient pressure

An apparatus for measuring variations in pressure, said apparatus comprising:

• means for containing a volume of liquid;
• an indicator float to be placed within said containing means and supported by said liquid contained therein, said float having upper and lower portions and a hollow interior portion for maintaining a compressible fluid therewithin, and being vertically movable within said containing means;
• means connected to said float for automatically providing a variable buoyancy equilibrium force to said float to offset buoyant forces created by said compressible fluid, whereby said equilibrium force is automatically varied in response to varying buoyancy of said float resulting from the changing volume of said compressible fluid in response to changing ambient pressures, said variable buoyancy means comprising a flexible ballast structure having top and bottom ends and supported adjacent its top end above the upper portion of said float such that said bottom end depends downwardly to said float;
• and
• means connected to the upper portion of said float for receiving a length of the bottom end of said ballast structure.