Wireless telegraphy by night has a notable phenomenon attached to it. " Technics " points out that there is conclusive proof that wireless telegraph signals can be transmitted to a greater distance by night than by day, the ratio of the distances being as 5 is to two. At first sight this appears to be very extraordinary, but recent investigations afford a very simple explanation of it. In wireless telegraphy, electric " tubes of force" are projected into space from the sparking apparatus at the transmitting station: if they reach the receiving station they affect the coherer or other receiving apparatus. Now, it has been proved that a heated body emits negatively charging particles, or electrons, each possessing about one-thousandth part of-the mass of a hydrogen atom. The sun, being at a high temperature, must emit these particles; some of these, when they reach the earth, strike aeainstthe gas molecules comprised in the atmosphere, and break these up into their constituent charged atoms. A single electron may dissociate a large nnmber of gas molecules. Hence in daylight the atmosphere contains numerous charged particles. If an electric field is established in the air during the daytime, the charged particles will travel along the " tubes of force". Now, the electric "tubes of force" projected from a wireless telegraph transmitting station, as they pass through the atmosphere, will set the charged particles in motion; since the charged particles possess inertia, energy must be absorbed when they are set in motion, and hence the "tubes of force " must lose energy and finally disappear. At night time the charged particles emitted by the sun are falling on the opposite side of the earth, since they travel in straight lines, like light rays; hence at night the atmosphere is practically free from charged particles, and is no longer rendered conducting. About two minutes after sunrise the atmosphere has become saturated with charged particles, and the absorption of the electric " tubes of force " has reached its maximum value. Since light consists of moving "tubes of force " similar to those utilized in wireless telegraphy, it might appear strange that light is not absorbed by the atmosphere; but in this case, owing to the very short length of the light waves, the field acting on a charged particle changes its direction about 4 x 101 5 times a second; therefore the particle is not set in motion, just as no deflection is produced in a galvanometer by a quickly alternating current. In wireless telegraphy the wave lengths utilized average about 300 ft., or 9,000 ems, and the field at any point in the line of transmission, is reversed about 0.5xl06 times per second.