AbstractIn various experiments in these laboratories it has become necessary to consider the effect on the energy dissipated in friction of a force acting normally to the direction of the flow‐path of a liquid. It appeared that such a case was analogous to that of a liquid constrained to flow in a coiled tube, wherein the energy dissipation is higher than in a straight tube of the same length and bore; and furthermore in the curved path a type of streamline motion persists to Reynolds' numbers which arc far greater than the lower limit of turbulence in a straight tube. The experiments described were carried out to test this analogy.