Roberts Tide Predicting Machine

In 1929, following the death of H. W. T. Roberts (the son of Edward Roberts), Doodson acquired the Légé-made machine that Edward Roberts had designed in 1906 and which had won a Grand Prix at the Franco–British Exhibition of 1908. Roberts had subsequently used it as part of his own tidal prediction business (Messrs. Edward Roberts & Sons of Broadstairs), with the work of that business, including predictions for the Hydrographic Office, also passing to the LTI in 1929.

This Roberts–Légé Machine (TPM-S5) simulated 33 constituents, several more than the Bidston Kelvin Machine. By 1929 it was in need of an overhaul and refurbishment. Shortly thereafter, the number of constituents was increased to 40 by Chadburns of Liverpool, with its original design having allowed for such a future expansion. Its dimensions are approximately 7 feet (2.1 m) high, 6 feet (2 m) long and 2.5 feet (0.8 m) wide (somewhat wider with its casing). It re- mained in use at Bidston until 1960 (Scoffield, 2006).

This TPM was sometimes known as the “Universal Tide Predictor of 1906” and also as the “Roberts Tide Predicting Machine”, a name which had previously been attached to the India Office Machine (TPM-S2) which had also been designed by Roberts. Doodson and Bidston staff referred to it as the “Légé machine”.