History of early ultrasonic blood flowmeters.

Methods of measuring flow of fluids by acoustic techniques before 1960 are reported, and motivation for such documentation is presented. Serendipity played a role in introducing acoustic flowmeters to the Institute of Experimental Medicine of the Mayo Graudate School of Medicine. Ultrasonic flowmeters promise to be clinically useful in procuring dimensions of blood vessels, in measuring flow transcutaneously, and in studying the dynamics of flowing blood within the diseased cardiovascular system.