Name: Compass
Brand: ULabs
Availability: InStock

Inspect the compass: the glass intact and free of cracks and scratches, the limb divisions and the cardinal-point markings clear, the rotating lid with the sight moving without binding and holding its set position. Check the locking brake: with the needle locked it stays still, and after release it swings freely.
Check the sensitivity of the needle. Holding the compass horizontally, release the brake, let the needle settle and note the reading. Bring a steel object up from the side, deflect the needle by a few tens of degrees and remove the object. A sound needle returns to the same position after several decaying swings. If the readings differ each time, the pivot point is blunt or dirty and the compass is unfit for measurement.
Choose the measuring place away from vehicles, metal fences, reinforced concrete structures, power poles and power lines. Put aside keys, a knife and a phone; a steel watch bracelet and metal spectacle frames also deflect the needle.

Hold the compass horizontally on the palm or place it on a level non-metallic support at about waist level. A tilted case makes the needle catch the glass or the bottom, and it stops in the wrong position.
Release the brake and wait until the needle comes fully to rest. A reading must not be taken from a needle that is still swinging.
To determine the cardinal points, turn the case until the north end of the needle coincides with the north mark on the scale. The cardinal-point markings on the limb then indicate north, south, east and west on the ground, and the zero division of the scale coincides with the direction to the north. Further measurements are made from this position of the case.
To measure an azimuth, keep the case in that position, turn the lid and aim the sight at the chosen landmark so that the object is seen through the slot and the front sight at the same time.
Read the value on the limb scale against the index: this is the azimuth of the direction to the landmark, counted from the direction to the north clockwise. Look at the scale perpendicularly from above; a sideways view introduces a parallax error.
To move along a set azimuth, place its value against the index, turn the compass in the horizontal plane until the north end of the needle coincides with the north mark on the limb, and set off in the direction given by the sight, picking out intermediate landmarks on the way.
After taking the readings, lock the needle and only then carry the compass.

The needle points to the magnetic pole, not to the geographic one. The angle between the magnetic and geographic meridians (magnetic declination) depends on the place of observation and is taken from the map of the working area to pass to a geographic azimuth.
Local magnetic anomalies, underground utilities, reinforcement, power lines and moving traffic deflect the needle. Repeat the measurement a few steps aside: if the readings change noticeably, the place is unsuitable for work.
The reading itself introduces error: a tilted case, an incompletely settled needle, a view of the scale at an angle, and rough aiming at a distant or extended landmark. Aim at narrow vertical objects such as a mast, the corner of a building or a single tree.
A systematic shift of the readings appears after an impact or a fall. After every such case repeat the needle sensitivity check and compare the readings with another sound compass placed alongside.

Do not bring magnets, steel objects, loudspeakers or other sources of a magnetic field near the compass: they distort the readings and can remagnetise the needle.
Carry and store the compass only with the needle locked; working with an unlocked needle blunts the pivot point and reduces sensitivity.
Do not open the case and do not remove the glass: a loss of tightness leads to contamination of the pivot and to the needle sticking.
Do not place the compass on metal surfaces and do not bring it close to electrical equipment during measurement.
Protect the compass from impact and dropping: they shift the pivot point, and the needle stops settling in the same position.
Before each use check the security of the fastenings and the integrity of the moving parts; learners work with the compass under the supervision of a teacher.

Wipe the glass and the case with a dry or slightly damp soft cloth. Solvents, alcohol and abrasives leave a haze on the glass and the scale, after which the divisions and the cardinal-point markings become hard to read.
Before each measuring cycle check that the needle returns to the same position after deflection and that the brake works. A needle that stops differently each time, or sticks to the glass, indicates a damaged pivot; such a compass is withdrawn from use.
Keep the compass in a dry room with the needle locked, apart from magnets, loudspeakers, tools and other steel objects. Long storage next to a strong magnet weakens or remagnetises the needle.

Store in a dry, clean, ventilated room at +5 °C to +40 °C and relative humidity of 60 %, non-condensing, protected from direct sunlight, moisture, dust and heat sources. Keep the storage air free of impurities that cause corrosion of metals.
Operating climatic conditions: air temperature +5 °C to +40 °C, relative humidity 40 % to 60 %, atmospheric pressure 84 to 107 kPa (630-800 mmHg).
During transport the packed product is secured against movement and protected from precipitation and impact; the product is supplied in the manufacturer's packaging.
The product is not electrical or electronic equipment and carries no WEEE marking. It contains no hazardous substances and is disposed of as municipal waste after separation by material, in line with the rules of the operating organisation and the applicable law.

Warranty obligations cover the elimination of defects and the replacement of defective parts or of the equipment for three years, and the availability of spare parts and consumables for five years.

Compass

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