The navigating equipment carried by Columbus probably was simply a compass, a cross-staff, and a table of the sun's declination. Another device used for finding latitude was the astrolabe. The altitude could then be read on a scale marked on the staff. To measure the altitude of a heavenly body, the instrument was sighted in that direction, and the cross was moved forward or back until the heavenly body appeared through the upper hole and the horizon through the lower. (66-cm) cross a small hole was bored, and at the end of the staff a sight was fixed. It consisted of two pieces of wood, the cross at right angles to, and sliding on, the staff. The cross-staff was used to find latitude early in the 15th cent. With the development of shipbuilding and the increase in knowledge of astronomy, there was increased use of instruments. there was progress by the Portuguese under the leadership of Prince Henry the Navigator, who built an observatory and formulated tables of the declinations of the sun collected a great amount of nautical information, which he placed in practical form made charts and sponsored expeditions that led to numerous discoveries. A tremendous advance in navigation had taken place with the introduction of the compass. During this period the study of bodies of water, or hydrography, was given much attention, and harbors and the outlets of rivers were surveyed and buoyed.
In England, Queen Elizabeth I did much to establish navigation laws, giving additional powers to Trinity House, a guild that had been created in 1514 for the piloting of ships and the regulation of British navigation. The Polynesians navigated from island to island across the open ocean using observations of guide stars and the moon, the winds and currents, and birds, knowledge of which was passed from generation to generation. They built large ships and, traveling out of sight of land by day and by night, probably circumnavigated Africa.
The Phoenicians were among the most daring of the ancient navigators. In ancient times, mariners navigated by the guidance of the sun and stars and landmarks along the coast. Please read the listing description and look at the photographs carefully.Navigation, science and technology of finding the position and directing the course of vessels and aircraft. I ship Canada Post Small Package Air.*** I am not responsible for custom or duty taxes or fees. International (USA) shipping can take UP TO 14 business days. ***BEFORE purchasing, please read my SHIPPING POLICIES. If you are outside of Canada and the USA and are interested in purchasing, please email me, I may be able to arrange shipping to your country. Any condition outside normal vintage wear, like chips or cracks or serious defaults, will be noted.***Īpril 2018 Update: I am now only shipping to Canada and the USA for many of my items. There may be naturally occurring manufacturer's defects, slight surface scratching, or wear consistent with normal use. Vintage or pre-owned items will often show some signs of wear due to their age. I do my best to research the item and its history and pass that information on to my customers. ***Please keep in mind, I am not an expert in jewelry or vintage items. The vinyl sheath has some minor wear and marks/stains?. This Military Aero collectible is in very good vintage condition the black lettering has wear expected for its age and use. This item comes in a vinyl sheath with instructions printed on the front. Property Aero products Research item measures 11 1/8 inches long and 4 7/8 inches at its widest. Offering this Vintage MB-4A Computer Air Navigation, Dead Reckoning Measure Slide. I am NOT responsible for any customs fees, duty fees, or taxes on international purchases.*
International (USA) shipping is subject to customs inspection, so please allow AMPLE TIME for your item to arrive. There may be postal delays due to the Coronavirus Pandemic. **Packages, depending on season, can take up to 14 BUSINESS days for delivery to the USA. *IMPORTANT* Please READ the listing description below.
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