| Weights and Measures Standards of the United States, A brief history | There is no internationally agreed symbol, but the symbol kn is commonly used |
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| Since the 1890s or thereabouts, it has been drummed into the young seaman that a knot is a unit of speed, namely, one nautical mile per hour; and that consequently only the uneducated speak of "knots per hour" or "knots an hour" | The knot is defined as one nautical mile per hour |
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