CTD monitor

Picture a column, starting at the surface of the ocean and descending to the ocean floor. Conceptualised by the discipline of oceanography, this is the area delineated for measuring qualities of the water, an architecture of modernity. A CTD is an instrument commonly used by oceanographers, which measures conductivity, temperature and depth within this region of water. It can gather high resolution data, however it can only do one cast at a time on the sample site – and many casts are needed to provide a picture of an ocean environment. By measuring hydrostatic pressure, compression, pressure, and local gravity field at a certain latitude, depth can be calculated. Then conductivity, temperature and depth are used to calculate water salinity. A CTD utilises sampling bottles, which close at different depths, by dragging the measure upwards through the water, a profile of the water column is created.

This logic follows long history of the way that the seascape has been imagined by different disciplines of Western science. CTD instruments which now rise through these vertical delineations, are preceded by hemp ropes, weighted with lead, which would be dropped from the side of a ship. As the rope dropped, it ran through the hands of the sailors. Knots on the rope, representing fathoms, were called out, and marked down with a quill pen.