The Doodson-Légé Tide Predicting Machine

The Doodson-Légé Tide Prediction Machine

Tidal predictions were first carried out in 1924 at Bidston Observatory (University of Liverpool Tidal Institute), initially by hand and then by early tide predicting machines.

The Doodson-Légé Tide Prediction Machine that was removed from Bidston Observatory, craned into building

The Doodson-Légé tide predicting machine c.1950, probably at Bidston Observatory, Wirral second largest tide predicting machine ever built. This was a development from the earlier Roberts-Légé machine and designed by Arthur Doodson in the late 1940s and manufactured by Légé & Co. around 1948-49. This much bigger machine was “easier” to set up and, after some additional mechanism added a few years later, could calculate the high and low tide levels and their times at once - effectively halving the time it took on the older Roberts-Légé machine. It is estimated that, using the Doodson-Lége machine, it could take almost a month to calculate a year’s worth of tidal levels for a particular port and these were calculated a couple of years in advance. In comparison, it takes the computers used today a fraction of a second to do the same calculation to greater accuracy. Throughout the 1950s though, this machine was state-of-the-art. Installing the machine at the National Oceanographic Centre Installing the machine at the National Oceanographic Centre The 1.8 ton Doodson-Légé and the 1.2 ton Roberts-Légé machines were recently transported to the NOC’s Joseph Proudman Building. The process took 5 ½ hours and required a large team of people. Staff at the NOC were in a jubilant mood watching the installation and cheered as the first machine to be lifted, the Roberts-Légé machine, touched down on the pavement beside the Proudman Building. The Doodson-Légé machine is a particularly symbolic object for them as it was at the heart of their tide prediction work for international ports from c1950 to the early 1960s."