A
ABACK to ADMIRAL of the fleet
Vice-ADMIRAL to AFTER-SAILS
AGENT-VICTUALLER to ALL'S WELL
ALL bands high to ANCHOR
To drag the ANCHORS to To fish the ANCHOR
To sheer the ship to her ANCHOR to Top-ARMOUR
ASHORE to AUGER
AWEIGH to AZIMUTH COMPASS
AWEIGH
AWNING
AZIMUTH-COMPASS
AZIMUTH COMPASS
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AZIMUTH COMPASS
The sun's azimuth is known to be an angle contained between the meridian and the center of the sun. When this is required, and his rays are strong enough to cast a shadow, the box is turned about till the shadow of the horizontal thread, or, if the sun be too low, till that of the perpendicular thread, in one stile, or the flit through the other, falls upon the line in the index bar, or vibrates to an equal distance on each side of it, the box being gently touched if it vibrates too far: at the same time they observe the degree marked upon the brass edge of the cat-gut line. In counting the degree for the azimuth, or any other angle that is reckoned from the meridian, the outward circle of figures upon the brass edge is used; and the situation of the index, with respect to the card and needle, will always direct upon what quarter of the compass the object is placed.But if the sun does not shine out sufficiently strong, the eye is placed behind the narrow flit in one of the stiles, and the wooden box turned about till Some part of the horizontal or perpendicular thread appears to intersect the center of the fun, or vibrate to an equal distance on each side of it; smoked glass being used next the eye, if the sun's light is too strong. In this method another observer is necessary, to note the degree cut by the nonius, at the Same time the first gives notice that the thread appears to split the object.
Plate II. fig. 20. is a perspective view of the compass, when in order for observation; the point of view being the center of the card, and the distance of the eye two feet.
A B. is the wooden box in which it is usually contained.
K. is a cat-gut line drawn from the inside of the box for determining the degree upon the brass edge.
L, M, N, 0. is the index bar with it's two stiles, and cat-gut threads, which being taken off from the top of the box, is placed in two pieces P Q, notched properly to receive it.
The other parts of the figure, with their references, are explained in. the article COMPASS.
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Reference Works |  |
© Derived from Thomas Cadell's new corrected edition, London: 1780, page 26, 2003
Prepared by Paul Turnbull
http://southseas.nla.gov.au/refs/falc/0092.html