Vacuum Recordings made at cow-side during milking are highly effective in detecting milking system inadequacies and malfunctions. This widely used technique is an outgrowth of research at University of California School of Veterinary Medicine, Davis, as early as 1957. Researchers Schalm and Noorlander conducted their investigations by recording vacuum levels with a strain gage amplifier. This electronic instrument is extremely sensitive and its measurements are accepted as the standard for accuracy. However, for use in the milking barn this equipment has several disadvantages— it is costly, complex, and fragile—and consequently, is seldom available.