Flash Spotting Instrument No.4 Mark III


The Insturment Flas Spotting No.4 Mark III is used in Survey Regiments R.A. by dlas spotting batteries for the quick measurement of horizontal and vertical angles, and for general oberservation of enemy territory. It is binocular instrument with a large field of view, designed to permit continuous observation without undue strain on the observers eyes.

It is an optical scal instrument i.e. the sub-divisions of each degree of horizontal and vertical angles are not obtained by means of verniers or micrometer heads but by fine reading scales which are viewed throught a microscope.