This involved measuring the magnetic deviation as the ship was oriented in several compass directions.

Magnetic deviation - to understand why a compass does not align perfectly with the Earth's north and south poles.

The name, meaning needles in Portuguese, is said to come from the fact that the compass's needle pointed true north there, without magnetic deviation.

In 1925 Rybin was appointed magnetic deviation chief of the Ob basin.

With the introduction of iron-clad ships the magnetic deviation observed in compasses became more severe.

He knew five languages, accumulated a collection of 1,100 American plants, observed the weather, and studied magnetic deviation and astronomy.

The construction of many early (mid-18th century) binnacles used iron nails, which were later discovered to cause magnetic deviations in compass readings.

The sources of magnetic deviation vary from compass to compass or vehicle to vehicle.

Magnetic deviation is the angle from a given magnetic bearing to the related bearing mark of the compass.

The second is magnetic deviation, the angular difference between magnetic North and the compass needle due to nearby sources of iron.

Thus, a comparison of bearings taken with such methods with the bearing given by a compass can be used to compute local magnetic deviation.

Halley also hoped that careful observations of magnetic deviations could provide a determination of longitude.

He proposed spherical charts and mentioned magnetic deviation and the existence of magnetic poles.

In navigation manuals, magnetic deviation often refers specifically to compass error caused by magnetized iron within a ship or aircraft.

Geoff taught us about polar navigation, and how to correct for magnetic deviation (the geographic and magnetic poles are distinct).

Compass error is divided into two parts, namely magnetic variation and magnetic deviation, the latter originating from magnetic properties of the vessel or aircraft.

Non-magnetic methods of taking bearings, such as with gyrocompass, astronomical observations, satellites (as GPS) or radio navigation, are not subject to magnetic deviation.

During the 1880s, Thomson worked to perfect the adjustable compass in order to correct errors arising from magnetic deviation owing to the increasing use of iron in naval architecture.

Magnetic deviation is the error induced in a compass by local magnetic fields, which must be allowed for, along with magnetic declination, if accurate bearings are to be calculated.

Flinder's proposal for the use of iron bars to be used to compensate for the magnetic deviations caused by iron on board a ship resulted in them being known as Flinders bars.

Charts use the Mercator projection so that bearings can be transferred to (or taken from) the charts directly, although allowances must be made for magnetic variation and magnetic deviation if accuracy is important.

Two other minor utility drivers came shipped with the AAF, one that replaced the transponder digits with the actual framerate, and one that provided correct magnetic deviation within the US scenery map.

Maturing during the fervor of the age of exploration, he devoted his life to the nautical sciences and developed the mariner's astrolabe along with investigating and proposing magnetic deviation and the existence of magnetic poles.

However, they began to realise that Franklin had little idea of where he was going either - his compass was of little use as the magnetic deviation for the area was unknown, and the constant cloud cover made navigating by the sun or stars impossible.

Martín Cortés de Albacar publishes Breve compendio de la esfera y del arte de navegar in Spain, an influential work in cosmography, proposing spherical charts and mentioning magnetic deviation and the existence of magnetic poles.