This apparatus is used to measure the dip angle of Earth’s magnetic field. When used horizontally, this apparatus can be used as a standard compass.  Vertically, it can be used to find the dip angle of the Earth’s magnetic field (inclination / declination).  
It consists of a freely moving magnetic needle that is vertically suspended in a non-magnetic frame.  A transparent full circle graduated plastic protractor is mounted in the frame on the back of the needle. The frame can be rotated on its axis to vary the angle of the needle, which can be read by a second mounted protractor. The frame is also equipped with two terminals to pass current for advanced experiments in inclination. 

Overall dimensions (approx.): 200 x 145 x 200mm.  Weight (approx.): 0.4kg.