an instrument for drawing large circles or arcs, consisting of a horizontal beam along which two vertical legs slide. Also called a trammel.Beam compass used for marking out an arc or circle; 25cm beam with 2 x 24cm extensions, 3 pencil lead holders and one nib in original box [damaged].W. H. Harling Ltd. London.beam compass, trammel

The Mowat Sensor model MS 01, is a pale green, palm-sized, plastic battery-operated device with a darker green switch on top. It is partially open at one end with two grilles. A microphone plugs into the other end with a wrist strap. It came with a brown vinyl carry case and owner's manual, which are not included. This handheld device for the visually impaired uses high frequency sound to detect objects within a narrow beam. The sensor vibrates if an object is present, responds to closest object within the beam. The vibration rate increases as user approaches object. There are two range settings: short, responds to objects less than 1 meter away (indoor use) and long, responds to objects of sufficient size up to 4 meters. The sensor can be handheld or carried in pocket or purse. As a facility intended for partially sighted people, the compass also includes an in-built color indicator (visible through the semi-transparent enclosure), which indicates the direction using a combination of three colours. Weight: 185 grams. Comes with dark brown vinyl case.1 pale green coloured plastic rectangle sensor with a brown nylon, plaited wrist strap Model MS01assistive devices, orientation and mobility