The Theodolite No.1

The Theodolite, optical scale 3,5inch, No.1 is an instrument used in R.A. Survey Regiments for the measurement of horisontal and vertical angles. The 3.5inch refers to the diameter of the horisontal engraved circle. The instrument os a transit theodolite, i.e. the telescope can be rotated through 180 degrees in a vertical plane.

 

The chief charateristic of this and other "optical scale" thedolites is that the minute and second sub-divisons of each degree on horizontal and vertical angles are not obtained by means of verniers or micrometer heads. Instead they are included on very finel divided scales photographd on to glass plates. The scales are viewed through microscopes.

 

 

The Theodolite, optical sclae 3.5inch no.2 is a full transit theodolite, i.e. the telescope can be rotated through 360 degrees in a vertical plane.

Verder