Estimates for tide water levels were once made using tidal prediction machines, which were beautifully engineered mechanical devices. These were a type of analogue computer and the predictions were surprisingly accurate considering how many factors affect the tides. In addition to the influence of the sun and the moon, these include the effects of orbital wobbles of the Earth, the depth and contours of the seabed, and the shape of the coastline. Indeed, some modern software programs take account of eighty or more so-called harmonics which, superimposed on each other, define the shape Continue Reading