The William Ferrel Tide-Predicting Machine

This was the first tide predicting machine used in the United States. It was designed by William Ferrel, a mathematician with the U.S. Coast and Geodetic Survey, and completed in 1882.

The machine summed 19 harmonic tidal constituents and gave direct readings of the predicted times and heights of the high and low waters. Predictions were made on this machine from 1885 through 1991.