Abstract : A test machine is described which will load specimens in compression at rates as high as 30 ips or 6000 %/sec for a 1/2 in. thick sample. The rate of compression and the shape of the % compression time curve is readily varied. The stress-% compression diagram associated with any given % compression time curve is plotted directly. An impact method which has been used to obtain stress-% compression diagrams with compression rates as high as 200,000 %/sec is discussed.