![]() ![]() He studied all the popular scientific topics of the period, especially magnetism, electricity, meteorolgy, and chemistry, and corresponded with many leading scientists, including Bonnet, Euler, Deluc, J. It also explained the diurnal variation of the earth's magnetic force.In 1767 van Swinden obtained the chair of philosophy, logic, and metaphysics at Franekar University. First edition of Van Swinden's large work on magnetism and the function of the compass and the variability of magnetic needles. ![]() 1-576, 3 folded engraved plates and 52 folded tables. ""Mémoires fe Mathematique et de Physique, Présentés à l'Academie des Sciences par divers Savans"", Tome VIII. Richly gilt compartments, title-and tomelabels with gilt lettering. full sprinckled calf with 5 raised bands on spine. Recherches sur les Aiguilles Aimantées, et sur leurs Variations régulières, qui ont portagé le Prix proposé pour L'Année 1777. THE PRIZE-WINNING MEMOIR ON MAGNETISM AND THE COMPASS. In an area with East declination, you'll subtract."SWINDEN, (JAN HENDRIK) VAN. You'll add the number of degrees necessary to get the correct corresponding bearing on your map. Say you take a bearing on your compass in an area with West declination.Find out the declination in the area in which you'll be traveling so you can compensate for it. East of that line, declination orients toward the West, meaning that Magnetic North is several degrees West of True North. In the US, the line of zero declination runs up through Alabama, Illinois, and Wisconsin, X Research source at a slight diagonal.To make using the compass much easier, you can correct for declination by either adding or subtracting the declination amount from your bearing in degrees, depending on whether you're taking a bearing from a map or from your compass, and whether or not you're in an area with East declination or West declination. Declination refers to the amount by which North on your map and North on your compass differ at any given point, given the Earth's magnetic field. It's important to compensate by taking the declination into account. Think of how off you'll be after ten or twenty miles. While the difference may seem incidental, traveling just one degree off for the distance of a mile will have you about 100 feet (30.5 m) off track.Depending where you are on the surface of the Earth, you'll have to account for the Magnetic shift to get an accurate reading. Magnetic North refers to the tilt of the magnetic field, about eleven degrees from the tilt of the Earth's axis, making the difference between True North and Magnetic North different by as many as 20 degrees in some places.Unfortunately, because of slight variations in the magnetic field, your compass won't point to True North, it'll point to Magnetic North. All maps are laid out the same, with True North at the top of the map. ![]()
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