Suppose now that we attach a weight, say a ball of beeswax, at the middle point of the string, so as to increase the vibrating mass. This weight will become a source of reflections and less wave energy will reach the farther end of the string than before. Subdivide the beeswax into three equal parts and place them at three equi-distant points along the cord. The efficiency of transmission will be better now than when all the wax was concentrated at a single point. By subdividing still further the efficiency will be yet more improved; but a point is soon reached when further subdivisions produce very slight improvement. This point is reached when the loaded cord vibrates nearly like a uniform cord of the same mass, tension, and frictional resistance; such a cord, bearing 12 small weights of beeswax, is represented as D when at rest, as E when in motion. . . . It is impossible so to load a cord as to make it suitable for waves of all lengths; but if the distribution of the loads satisfies the requirements of a given wave-length, it will also satisfy them for all longer wave-lengths. A cord of this kind has mechanical analogy with an electrical wave conductor. In a wire transmitting electricity inductance coils may be so placed as to have just the effect of the bits of wax attached to the cord in our illustration; in both cases the waves are transmitted more fully and with less blurring than in an unloaded line. The mathematical law of both cases is the same. It was in ascertaining that law so as to know where to place his inductance coils that Professor Pupin arrived at success. Preceding inventors, missing this law, came only to failure. He constructed an artificial cable of 250 sections, each consisting of a sheet of paraffined paper on both sides of which was a strip of tin-foil, the whole fairly representing a cable 250 miles in length. At each of the 250 joints in the course of this artificial circuit he inserted a twin inductance coil wound on one spool 125 millimetres broad and high, and separated by cardboard 1/64 inch thick. Each coil had 580 turns of No. 20 Brown & Sharpe wire. Just as with the weighted rope this circuit transmitted its current much more efficiently than if the inductance coils had been absent.