Editing Depth gauge (section)

=== Bourdon tube depth gauge ===
{{main|Bourdon gauge}}
[[File:Manometer anim 02.gif|right|thumb|Bourdon tube]]
The Bourdon tube depth gauge consists of a curved tube made of elastic metal, known as a [[Pressure measurement#Bourdon gauge|Bourdon tube]]. Water pressure on the tube may be on the inside or the outside depending on the design. When the pressure increases, the tube stretches, and when it decreases the tube recovers to the original curvature. This movement is transferred to a [[Indicator (distance amplifying instrument)|pointer]] by a system of gears or levers, and the pointer may have an auxiliary trailing pointer which is pushed along but does not automatically return with the main pointer, which can mark the maximum depth reached. Accuracy can be good. When carried by the diver, these gauges measure the pressure difference directly between the ambient water and the sealed internal air space of the gauge, and therefore can be influenced by temperature changes.