A paper, on the patent azimuth and steering compass invented by E.J. Dent ... [together with a paper on the shape of the wheel-teeth in the clock for the new Royal Exchange] / Presented to the ... British Association for the advancement of science ... 1844.

  • Dent, Edward John, 1790-1853
Date:
1844
Catalogue details

Licence: Public Domain Mark

Credit: A paper, on the patent azimuth and steering compass invented by E.J. Dent ... [together with a paper on the shape of the wheel-teeth in the clock for the new Royal Exchange] / Presented to the ... British Association for the advancement of science ... 1844. Source: Wellcome Collection.

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    axis drawn through the N. and S. points of the card ; and the time of its vibration is then a minimum. In any other motion of the vessel, the corresponding motion of the card is compounded of these two effects, which produces the waddling”” or undulatory motion observed when the motion of the vessel is considerable and irregular ; and the cause of which, I believe, has not been previously assigned. However well, therefore, the gymbal apparatus, in which the card is placed, is balanced, yet as the card has a motion or time of vibration peculiar to itself, depending upon the position of the axis of its vertical vibrations with respect to the axis of the Needle— which vibrations are not altogether under the control of the gymbals although its vibrations are continually checked, and its quiescence disturbed by it in consequence of the supporting pin coming in contact with the sides of the cup, as before mentioned — yet in the present construction of the Binnacle Compass, the card ever will be subject to irre¬ gular deviations from the horizontal plane, arising from this cause. The mode by which (1 trust) I have removed these evils has been, by altering the nature of the suspension ; that is, by suspending the card in a similar way to the balance of a Chronometer, and with equal delicacy, both ends of the pivot acting on diamonds, and the holes jewelled, by which means the card is constrained to move very nearly in the horizontal plane, since in this respect it is entirely under the control of the gymbals. The friction is also considerably reduced by this mode of suspension. The groat accuracy with which the card returns to the same position has been clearly shown by a great number of experiments ; and I am not aware of any mode which offers so severe a test in the present case, as the agreement between consecutive observations. To