A resistance tide gauge
Norman Brown Pigeon · Defense Technical Information Center (DTIC) · 1967
The design, construction, calibration, and field application of a simple resistance-type tide gauge are presented. The gauge measures coastal water level in relation to an elevation reference. A summary of previously available tide gauges is made with advantages and disadvantages noted. The gauge sensor consists of a high resistance wire within a mercury-filled capillary. The mercury level in the capillary is pressure-linked to the sea water column and responds to changes of water level over a wide period range. The mercury column height changes the current-conducting length of the resistance wire in the capillary. the change in resistance is, therefore, linear with column height. The resistance element forms one arm of a Wheatstone bridge, Laboratory evaluation and calibration are described. Recorded field observations of the resistance gauge are compared to the record of a "standard" tide gauge at the same location