The object of this thesis is to design, build, and calibrate a coal-air flowmeter to operate in a pipe line through which a mixture of powdered coal and air are being blown; and to investigate the accuracy of the meter while operating at different air-fuel ratios. It is the authors intention to test the coal-air flowmeter in a pipe line in which conditions exist that closely simulate actual conditions that exist in power plants burning pulverized coal. The flow characteristics of the meter will, as near as possible, be the same as may be found in a typical industrial application. For this reason, a large size pipe line will be used and the air pressure in the pipe lin will be relatively low. It is believed that a coal-air flowmeter has not before this time been investigated in a large pipe and utilizing low pressures. Because of conditions over which the authors had no control, flyash had to be substituted for coal for the testing of the coal-air flowmeter. The authors are mainly interested in the measurement of the flow of coal and therefore have referred to the meter as a coal flowmeter throughout this thesis. The authors believe the use of flyash as the test medium will demonstrate the usefulness of the meter to measure the flow of any type of finely divided particle being carried by an air stream. / M.S.