Abstract: The invention is an improved method and apparatus for determining the quantity of solids being conveyed in a slurry that is moving in a pipe. The method and apparatus combines a density-sensitive flowmeter (elbow meter) with a density-insensitive flowmeter (ultrasonic doppler flowmeter) to determine the quantity of solids conveyed in a slurry that is moving in a pipe. Velocity is determined by using a sonic flowmeter which is not affected by slurry specific gravity. Specific gravity is determined by dividing the signal from an elbow meter, which is a linear function of specific gravity, by the square of the sonic flowmeter signal. Numerous methods and apparatus are included to improve the accuracy of both the sonic flowmeter and the elbow meter.