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Tide-Predicting Machine No. 2, also known as Old Brass Brains, [1] was a special-purpose mechanical computer that uses gears, pulleys, chains, and other mechanical components to compute the height and time of high and low tides for specific locations. The machine can perform tide calculations much faster than a person could do with pencil and ...
The first tide predicting machine (TPM) was built in 1872 by the Légé Engineering Company. [11] A model of it was exhibited at the British Association meeting in 1873 [12] (for computing 8 tidal components), followed in 1875-76 by a machine on a slightly larger scale (for computing 10 tidal components), was designed by Sir William Thomson (who later became Lord Kelvin). [13]
That is, by proper association of the astronomical phases, observations made at one time can enable predictions decades away with different astronomical phases. [citation needed] Doodson used and became involved in the design of tide-predicting machines, of which a widely used example was the "Doodson-Légé TPM".
Tide tables, sometimes called tide charts, are used for tidal prediction and show the daily times and levels of high and low tides, usually for a particular location. [1] Tide heights at intermediate times (between high and low water) can be approximated by using the rule of twelfths or more accurately calculated by using a published tidal ...
The original machines could not add, but then it was noticed that if the two wheels of a rear differential are turned, the drive shaft will compute the average of the left and right wheels. Addition and subtraction are then achieved by using a simple gear ratio of 1:2; the gear ratio provides multiplication by two, and multiplying the average ...
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A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [1] Common chart datums are lowest astronomical tide (LAT) [1] and mean lower low water (MLLW).
Ferrel collected data on the tides, and used this to calculate the mass of the moon. [2] In 1880, he proposed to the Superintendent of the Coast and Geodetic Survey a machine which could use data to predict the tidal maxima and minima. He also presented this idea to the American Association for the Advancement of Science later in the same year. [2]