Basic fluid elements are described. Sequential fluidic circuits using gases as the working fluid are being employed in machine tools and many other applications; circuits using hydraulic fluids or other liquids have not been as highly developed. The primary problems appear to be lower operating speed, higher power losses, and entrapped air. There still appear to be many advantages in using hydraulic fluidics to replace systems involving many moving parts. Hydraulic fluidic feedback control systems would offer even greater advantages in cost and reliability.