Description of the Apparatus Used for Testing Current-Meters, at the Admiralty Works at Torquay for Experimenting on Models of Ships

Robert Gordon
1884 Proceedings of the Institution of Mechanical Engineers  
The Current-Meters to be testcd arc towed by a dynamometrical apparatus through still water in a large tank, which gives a parallelsided water-space 278 ft. long, 36 ft. broad, and for the most part 10 ft. deep, though it shallows up at the ends. I t is roofed from end to end, the framework of the roof carrying a light railway with a clear space between the rails, which run the entire length of the building at about 20 inches above the normal mater-level. I n Figs. 1,2, and 3, Plate 24, is
more » ... the general arrangement of tank and railway. A stout-framed truck T, Fig. 4 , Plate 25, suspended from the axles of two pairs of wheels, runs on the railway, and carries the recording and measuring apparatus. A sheet of paper is wound round a cylinder R, carried by the truck ; and the cylinder is moved by a band from the hinder axle, so that thc circumferential travel of the paper represents, on a reduced scale, the forward motion of the truck. A pen A, actuaied by clockwork, marks time on the cylinder as it revolves. A second pen B is moved electrically, and marks indents on thc recording paper for every 25 ft. run by the truck. A third pen C, moved electrically, can be used for recording the number of revolutions made by the meter under trial, contact being made inside the meter in thc method actually arranged for use. A fourth pen D is required for recording the force actually used for towing the object through the water. Generally not more than three or four pens are used at one time for recording: another occasional pen E is sometimes required to show slight quick or slow variations in the ratc of speed of the truck and object during the experiment. The
doi:10.1243/pime_proc_1884_035_022_02 fatcat:x55nhycecnb25gcmuhr3isvvrm