Marching and traversing compasses are built on the same basic design as sighting and geologic compasses but without sighting alidades. Some have a normal compass needle, others a rotating compass card with a fixed azimuth dial around the periphery. Developed in the early 1900s, the compass case is commonly filled with fluid to dampen or slow down the otherwise erratic movement of the compass card that rests on a pivot with the magnetic needle attached either on top or bottom of the card. Compasses of this type are usually small and fitted with a hinged lid, sometimes with a ‘Hunter’ glass window.