The Plane Table Alidade was used as the sighting Instrument in the production of historical manual hand drawn maps. A Plane Table Board mounted on a tripod is levelled and the Alidade is placed on the table with the vanes perpendicular to the it. Each sighting vane has a central thread lined up on the target and the angle to that target point is then drawn on the map sheet using the beveled fiducial edge. Plane Table Surveying is used as a quick method where less accuracy is required or needed. Plane table Surveying is a relatively portable and inexpensive method and was used extensively before the advent of sophisticated surveying instruments. The photo at 6489.2 is an Australian Army Survey Corps Party using a Plane Table Alidade in Syria during WWII. See also item 6580 which is the Plane Table with tripod legs that was used with the Alidade.Two Plane Table sighting instruments (Alidade) used for historical manual map making housed in wooden transit boxes. A brass instrument with folding sights at each end and a beveled fiducial edge in one edge. The front sight is the object vane and the rear sight is the sight vane. There is a sliding arm attached to the base to draw parallel lines to the fiducial edge. Very slight differences in model between these two instruments.First Instrument, "ER Watts and Son, London, 1938, MkII, Box Label 423. Second Instrument - R. E-Co, Mk.II, stamped E686, Box Label 686.royal australian survey corps, rasvy, fortuna, army survey regiment, army svy regt, asr

Possibly used for surveying pipe linesSurveying Aneroid Compensated

Associated with object 467.2Cylindrical black sight with metallic fixtures and split sight. Adjustable base with screws.Logo in triangle on side of barrel: 'ERW&S' Stamped on underside of base: '2C'er watts & sons, spectroscopy, sight, optical equipment, surveying

E. R. Watts and Son, makers of theodolites and other surveying instruments, of 123 Camberwell Road, London. The company was established in 1856 by Edwin Watts at twenty-three he had saved £100 from his earnings to start the business with his staff consisting of one boy and later Alexander Clarkson as an apprentice with the workshop a small room over a Bemondsey stable. Watts' first order was from Negretti and Zambra for a mining dial Alexander Clarkson In the early days the firm worked mainly on marine compasses. Edwin Watts would go down to the Docks to adjust the compasses once they had been installed on the ships. In May 1873 the business moved to larger premises a house with a garden. The workshop was also the home of Mr and Mrs Watts and their five sons and three daughters. By now there were fifteen to twenty men employed by the firm. The company were commissioned to supply the Theodolites and Levels for the construction to the Canadian Pacific Railway in 1881. Towards the end of the century, the firm began to make heliographs continuing to produce them for the government until just before the Second World War when by agreement assigned their manufacture to another firm. 1904 The first dividing engine was completed by George William Watts. It was so remarkable an instrument at the time and for years afterwards, In 1907 Arthur Ames went to Canada and started an organisation in Winnipeg in 1909 this became a separate company called E. R. Watts and Son Ltd. of Ottawa. This firm developed considerably and was eventually with the co-operation of three other instrument companies (Cambridge Instrument Co, Ross, and Negretti and Zambra), were reconstituted as ”Instruments Ltd” of Ottawa and Toronto. During the next ten years, the firm expanded greatly to include glass grinding, leather work, dividing and engraving, testing, adjusting and packing. This expansion was continued during the First World War when workshops were completed and the machinery installed and running within eleven weeks from the start of construction. During the war, a Sergeant Coles, among the rats, lice and mud of the trenches, fitted various bits of scrap into his cocoa tin and made the first Flash Spotter for plotting the positions of enemy guns. Coles was rushed home to the firm's factory where he and George William Watts designed a spotter not made out of a cocoa tin and as a result, the Watts Vertical Force Variometer was developed during WWI. Other Watts instruments made in the First World War included the Light Mountain Theodolites which were taken on Mt Everest expeditions. In 1919 ER Watts and Sons was incorporated as a limited company and in 1939 G. A. Whipple joined the Board of Directors. Shortly afterwards, Frank Charles Watts died having been Chairman of the firm for over 37 years and seen it through the First World War with all its expansions and difficulties. He was succeeded by his brother George William Watts with the vacant post of Managing Director being filled by G. A. Whipple. During the Second World War, the company expanded further and the number of employees rose to well over 1,300. In 1946 Watts acquired 78% of Adam Hilger and the microscope maker James Swift and Son Who were Manufacturers of Theodolites, Levels, Alidades, Meteorological Instruments, Variometers, and many other types of scientific instruments Then in 1948 the company amalgamated with Adam Hilger as Hilger and Watts which was then incorporated as a public company.Naval Rangefinder with a vertical wooden handle, and an arrangement of optical lenses. Three reversible brass inserts calibrated on both sides in yards, correspond to various base heights, (20 and 25 feet, 30 and 35 feet and 40 and 50 feet). They are fitted along the axis of the instrument. When the scale for the appropriate base height is selected and inserted, the carriage can be slid for coincidence and the distance read at the index mark on the sliding carriage.inscribed "Rangefinder Cotton Type Mk II" Calibrated scale up to 5000 yds (50 ft), 5000 yds (35 ft), 4000 yds (25 ft) made by E. R. Watts & Son.flagstaff hill, warrnambool, shipwrecked coast, flagstaff hill maritime museum, maritime museum, shipwreck coast, flagstaff hill maritime village, great ocean road, rangefinder, cotton type, e r watts & sons, naval range finder, marine equipment