It was his tutor Rev. E. W. Barnes who suggested that Proudman write to Horace Lamb at Manchester for a suitable topic of research. This started him on his studies of the dynamics of tides which was to become his main scientific interest. He returned to Liverpool as a lecturer in 1913, was appointed the first professor of applied mathematics in 1919 and in 1933 transferred to the chair of oceanography to which he brought a change of emphasis from biological to physical oceanography. He held this post until his retirement in 1954. In 1916 Horace Lamb asked Proudman to assist him in preparing a report for the British Association on the state of research on ocean tides. This led Proudman to the idea of founding an institute for research into all aspects of tides, an idea which was brought to fruition in 1919 with the financial aid of the Booth brothers, two Liverpool ship-owners. The University of Liverpool Tidal Institute started its work with Proudman as Honorary Director and A. T. Doodson as Secretary and in a few years acquired a national and international reputation for its tidal prediction services as well as for fundamental research. It is stated that from 1924 up to the 1950s the Institute was responsible for predicting tides for two-thirds of the world. After several changes of name and status the Institute (having amalgamated with the Liverpool Observatory in 1929) is now the Proudman Oceanographic Laboratory (see external links below).