A magnetic needle compass with a 30 mm body for determining the cardinal directions and measuring azimuths in geography, topography and field practicals.
This compass is used to orient oneself on the ground: to recognise the cardinal directions, to measure the direction to a chosen landmark, that is the azimuth, and to align a map with the real position of objects. The instrument is used in geography lessons, in the course of topography and geodesy, and during hiking trips and field practicals, when the direction of travel or one’s own location has to be established. The limb of the instrument has a scale from 0 to 360 degrees with the marks of the cardinal directions – north (N), east (E), south (S) and west (W).
A magnetised needle is freely mounted on the point of a bearing inside the body of the compass and settles along the magnetic meridian under the action of the Earth’s magnetic field. The circular limb of the body is graduated from 0 to 360 degrees and marked with the cardinal directions, so the direction is read directly from the scale. A rotating lid fitted with a sight and a reading index is placed on top and is used to determine the azimuth to a chosen landmark. During carrying, the needle is held still by a brake catch, which is released before measuring to bring the needle into the working position. The product needs no power source.
The compass is a magnetic needle compass with a body diameter of 30 mm. It is held in the hand during measurement and is supplied ready for work, requiring no preliminary adjustment. The conditions of use are the premises of an educational institution at an air temperature of +5 to +40 degrees Celsius and relative humidity of 40 to 60 % without condensate. Marking and operating documentation are in Ukrainian, and the marking carries the trade mark, the model and a place for an inventory number. The service life is 5 years and the warranty period is 12 months.
The set includes the compass assembled, comprising the body, the limb and the rotating lid with the sight – 1 pc, a passport with a warranty card – 1 pc, and individual transport packaging – 1 pc. The product is fully assembled and ready for use and needs no additional adjustment or assembly.
To determine the cardinal directions, the brake catch is released and the compass is held horizontally at chest level, away from metal objects, until the needle settles with its coloured end pointing to magnetic north; the limb is then turned so that the north mark coincides with the settled end of the needle, and the other cardinal directions are read from the corresponding marks of the scale. To measure an azimuth, the lid is opened, the sight is aimed at the chosen landmark and the reading is taken at the point where the reading index of the lid crosses the scale of the limb. For travel along a known azimuth, the limb is turned until that value coincides with the reading index and the observer turns with the whole body until the settled end of the needle meets the north mark. To orient a map, the side edge of the body is laid along the meridian line of the map and the map is turned together with the compass until the settled end of the needle meets the north mark.
The compass is used under the guidance of a geography teacher, and students are admitted to independent work after instruction in labour safety. The magnetic needle is sensitive to external magnetic fields, so during measurement the compass is kept at a distance of 30 cm from mobile telephones, metal objects and other magnets. Before the instrument is put away, the lid is closed and the needle is fixed with the brake catch. The body and the lid are wiped with a dry soft cloth and dust is removed from the scale of the limb with a soft brush; the compass is not immersed in water, disassembled, heated or left on radiators, and solvents, alcohol and aggressive cleaning agents are not used. It is stored in a dry room at +5 to +40 degrees Celsius and relative humidity of 80 %, away from magnets, powerful electrical appliances and radiators.
