National Archives a growing selection of early maps, in medium res. I also describe my own collection, which consists of vintage [i.
Compass Parts and Terms: Index Mark--This is where you read your bearing.
These lines do move with the whole dial, though. Declination Adjustment Scale--the degree lines located on one half of the inner part of the dial. North Orienting Arrow--the red arrow that can move to adjust for declination. This arrow, made up of two parallel lines, is often referred to as "the shed.
This needle is often referred to as "Fred. Now, think of the earth as a huge magnet with two poles -- magnetic North Pole and magnetic South Pole -- with invisible, magnetic lines connecting them.
The compass needle points along those magnetic lines, but the magnetic pole is separated from the geographic North Pole by more than 1, miles. So one has to adjust for this difference in order to use the compass with a map.
The angle between the magnetic North Pole and the geographic North Pole from a certain place is called declination.
And declination changes from place to place as well. Be aware that certain things can interfere with the compass needle, causing deviation from magnetic north.
These circumstances include the presence of steel and some local ore deposits. Even a steel wrist watch can cause such deviation, as will current-carrying, high-voltage wires. Strong magnetic fields can permanently affect the accuracy of a compass, so be sure not to store your compass near magnets or devices that can cause magnetic fields.
In order to use compass bearings back and forth from a map true and the field magnetic and vice versa, an adjustment must be made.
If this adjustment is NOT made, your compass work will likely be very inaccurate. Be aware that a one degree error can put you off course by about feet in one mile.
The easiest method to take declination into account is to buy a compass with a declination adjustment. Declination is said to be either easterly or westerly, depending on which side the magnetic North Pole is from a particular area, with respect to the "line" drawn towards the geographic north pole.
The zero declination line runs from the west coast of Florida up to eastern Minnesota at the Canadian border. To find the declination on a USGS topo map, look in the lower margin.Visualizing the Planimetric Accuracy of Historical Maps with MapAnalyst Bernhard Jenny, Adrian Weber, and Lorenz Hurni Institute of Cartography / .
Base product features and probable rates of visibility for planimetric map products and services. Feb 15, · The natural features usually shown on a planimetric map include rivers, lakes and seas; mountains, valleys and plains; and forests, prairies, marshes and deserts.
The cultural features include cities, farms, transportation routes and public utility facilities; and political and private boundary initiativeblog.com: Resolved.
Disclaimer. The maps and other digital, graphic or tabular information provided by the City of St. Peters were compiled from surveys, recorded deeds, plats, planimetric maps, and other public domain records.
A planimetric map presents only the horizontal positions for the features represented. It is distinguished from a topographic map by the omission of .
The DC GIS program collects planimetric mapping layers using aerial photography and photogrammetric principles meeting the American Society of Photogrammetry and Remote Sensing (ASPRS) standards. When creating planimetric datasets, OCTO GIS ensures they meet or exceed ASPRS large scale and scale mapping.
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