The effect of these two phenomena is to permit a condenser to be charged to a high potential and then, by the disappearance of the resistance of the interrupter, to discharge it very rapidly. The result of this action is to set up violent and rapid current impulses in the circuit containing the condenser, and thence in the sending wire. The current impulse, being very powerful, will enable messages to be sent to great distances, and as the number of oscillations per second can be controlled, this permits of selective signaling. The number of impulses can be made very high--above a million a second. The device is inexpensive and durable. It is considered a great contribution to wireless telegraphy and establishes it on a commercial basis, and selective signaling is solved and trans-Atlantic transmission will be easy. Radium is a rare metal recently discovered, having remarkable qualities and very difficult to obtain. It is a constituent of pitchblende, which is found in many places, but only in a small way. So far all that has been procured has come from a mine in Cornwall. A ton of pitchblende carries about 15½ grains of radium and it is very difficult to extract. A grain is estimated to be worth $200,000 and a kilogram is worth about $2,000,000. There is only about one pound of radium in the world. It is estimated to be worth $1,000,000. Radium was discovered by M. and Mme. Curie, in France, after they had familiarized themselves with the remarkable properties of uranium and polonium. Radium has many curious and inexplicable qualities. It continually emits heat and light without combustion, without chemical changes of any kind, and without any change in its bulk, appearance or molecular structure, which remains identical after many months. It is so powerful in the energy it constantly hurls forth as to entail many dangers in handling it. Sir Wm. Crookes says in describing it: "Probably if half a kilogram were in a bottle on that table it would kill us all. It would most certainly destroy our sight and burn our skins to such an extent we could not survive. The smallest bit placed on one's arm would produce a blister it would take months to heal." It also emits electrons with a velocity so great that Prof. Crookes estimates "one gram is enough to lift the whole of the British navy to the top of Ben Nevis, and I am not quite certain that we could not throw in the French fleet as well." It has such surprising properties that Lord Kelvin was moved to say of it that, "it threatens to overthrow the correlation of forces," which is the rock-ribbed, foundation postulate of science. It seems already to have unsettled the accepted theory of light, and after the experiments of the Russian scientists who are now investigating it, Profs. Mendelief, Yigooff and Borgruan, the result may give us new scientific theories and a new nomenclature.