Home Security Systems By Irfan

• An optical square is a hand instrument used by surveyor's to lay off right angles that are multiples of 90 degree or of 45 degree.
• They normally comprise of two optical glass mirrors in a sturdy Brass housing.
• Used for placing points on a line, offset measurements, setting our curves or determining horizontal plans.
• Optical Square is more accurate than the cross staff and it can be used for locating objects situated at larger distances.
• It is small and compact hand instrument and works on the principle of reflection.

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