The flow of water through pipes.—Experiments on stream-line motion and the measurement of critical velocity.

In a brief note published in the ‘Physical Review,’ we have described a thermal method of observing the change from stream-line to eddy motion for water flowing through pipes of different diameters. This method we have recently employed in a series of experiments, which we have carried out on a much larger scale than was previously attempted. The method had several points to recommend it for our particular work, the chief one being the simplicity of the experimental arrangements. The object in undertaking this investigation, for which our method was adapted, was in the interest attached to a study of stream-line flow, where every form of initial disturbance was as completely removed from the water as possible.