This version measures a temperature
gradient of water flowing between downstream
and upstream positions in a 1.3-cm diameter flow
tube attached to a benthic chamber. Heat is
generated continuously within the column by a
nichrome heating element and the temperature
gradient is measured by a pair of thermisters. When
there is no water flow, the temperature difference
between the two sensors in the column is at a
maximum, and this gradient decreases with increasing
the flow velocity.