A Theory of a general artificial electric line circuit, including T-line and μ-line as its special case, is given. This theory is utilized to deter mine a simple method of design of a compensated μ-type artificial electric lines whose electrical characteristics can be more approximated to the actual uniform line than a common T-line or μ-line, when the artificial line is required to work, not at a single frequency, but in a definite range of frequencies. (Sept. 1922)