Patented 18th Sept. 1866 Walker’s A2 Harpoon Ship Log Marine Navigation Device

Log o solcometro contamiglia nautico in ottone a forma di harpoon, signed T. Walker's Patent Harpoon Ship Log A 1 London , from the second half of the 1800s. It is an ancient nautical instrument, very rare and with a characteristic shape, which measured the distance and speed of a ship. Veniva gettato fuori bordo e trascinato dietro la nave stessa; ruotando grazie alla sua elica, trasmetteva il numero di giri fatti su se stesso ai tre quadranti realizzati su una placca in metallo smaltato posta al centro del log; i quadranti riportavano le misurazioni in miglia da 0 a 100 in decine, da 0 a 10 in unità, da 0 a 1 in quarti. I dati venivano poi letti ogni ora per ricavare anche la velocità. Good condition replaced flap perfectly working and mounted on custom-made brass wood base. Measurements length cm 54 - 21.2 in, propeller diameter cm 13 - 5.1 in. The last photo is the gift box. In past centuries, the attempt to measure the speed of ships was severely hampered mainly by the 'unavailability of time-measuring instruments of sufficient accuracy: by throwing a piece of wood overboard from the bow of a ship and measuring the time it took to reach the stern, it was possible to obtain some information about the speed of the ship itself, but with many errors and inaccuracies. The principle of the mechanical solcometer was explained to the Royal Society in 1699 by Robert Hooke, but the first model produced for commercial use was not patented until 1802 by Edward Massey...

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