Tide-Predicting Machine No. 2, also known as Old Brass Brains, was a special-purpose mechanical computer that uses gears, pulleys, chains, and other mechanical components to compute the height and tim
Tide Predicting Machine No. 2
This photo shows the largest of the three sections of Tide-Predicting Machine No. 2. The gears on the left transmit power from the hand crank. The components on the right contribute to the computation of the time of high and low tides.
A tide formula component crank on Tide-Predicting Machine No. 2. The mechanical arrangement (a slotted crank yoke) converts circular motion to a vertical motion that traces a sinusoid. The operator adjusts the position of the pin on the crank to represent a component of the tide formula at a specific coastal port before starting computations. The pin position affects the amplitude and phase of the sinusoid.
mechanism for generating sinusoidal motion component
Theory of tides
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The theory of tides is the application of continuum mechanics to interpret and predict the tidal deformations of planetary and satellite bodies and their atmospheres and oceans under the gravitational
Tide-Predicting Machine No. 2
…very challenging as it depends on multiple factors–including the alignment of the Sun and Moon, the shape of the coastline, and near-shore bathymetry. Tide theories attempt to account for these factors but lead to complex calculations. Originally, calculations were performed by hand, which was very labor-intensive…
High and low tide in the Bay of Fundy
A. Lunar gravitational potential: this depicts the Moon directly over 30° N (or 30° S) viewed from above the Northern Hemisphere. Note however that the moon is never more than about 28.6° north of the equator.
B. This view shows same potential from 180° from view A. Viewed from above the Northern Hemisphere. Red up, blue down.