This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1852 Excerpt: ...card is to be stopped when the sun is bisected by the thread in the other vane. The observation should be made when the sun's lower limb appears somewhat more than his semidiameter above the horizon, because his centre is really then in the horizon, although it is apparently elevated, on account of the refraction of ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1852 Excerpt: ...card is to be stopped when the sun is bisected by the thread in the other vane. The observation should be made when the sun's lower limb appears somewhat more than his semidiameter above the horizon, because his centre is really then in the horizon, although it is apparently elevated, on account of the refraction of the atmosphere: this is particularly to be noticed in high latitudes. To observe the Sun's Azimuth. Raise the magnifying-glass to the upper part of the vane, and move the box, as before directed, until the bright speck falls on the other vane, or on the line in the horizontal bar; the card is then to be stopped, and the divisions being read off, will be the sun's magnetic azimuth. If the card vibrate considerably at the time of observation, it will be better to observe the extreme vibrations, and take their mean as the magnetic azimuth. When the magnetic azimuth is observed, the altitude of the object must be taken, in order to obtain the true azimuth. It will conduce much to accuracy, if several azimuths be observed, with the corresponding altitudes, and the mean of the whole taken for the observation. To find the Variation of the Compass by an Amplitude. m Rule 1. With the given time and longitude, find the corresponding time at Greenwich, by the Rules in page 155, and to that time reduce the sun's declination, (XXI.) taken from Table X., or the Nautical Almanac. 2. To the log. secant of the latitude of the ship, rejecting the index (XXV.), add the log. sine of the sun's reduced declination; their sum will be the log. sine of the true amplitude, to be reckoned from the east in the morning, or from the west in the afternoon, towards the north or south, according to the declination. 3. Then, if the true and magnetic amplitudes be both north, or ...
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Add this copy of A Complete Epitome of Practical Navigation to cart. $29.16, new condition, Sold by Ingram Customer Returns Center rated 5.0 out of 5 stars, ships from NV, USA, published 2022 by Legare Street Press.
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Add this copy of A Complete Epitome of Practical Navigation to cart. $56.94, new condition, Sold by Russell Books rated 4.0 out of 5 stars, ships from Victoria, BC, CANADA, published 2022 by Legare Street Press.
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Seller's Description:
Very Good. 1860. hardcover. 360pp. "Contaning All Necessary Instructions For Keeping A Ship's Reckoning At Sea: With The Most Approved Methods Of Ascertaining The Latitude, By Meridian, Single, Or Double Altitudes; And The Longitude, By Chronometers, Or Lunar Observations; Including A Journal of a Voyage from London to Madeira, And Every Other Particular Requiaite To Form The Complete Navigator; The Whole Being Rendered Perfectly Easy, And Illustrated By Several Engravings. To Which Is Added A Correct And Extensive Set of Tablets, Preceded By A Copious Explanation Of Each Table." Bound in modern quarter leather and marble boards, spine in gilt. Some pages are a little dark, but text is clear. Strong, tight binding.....We ship daily from our Bookshop.
