does in the science of electricity: both of them are misnomers. When the ice is all melted potential energy is no longer stored, but is manifested in the sensible heating of water, the degree of which is measurable by the thermometer, until it reaches the boiling point, where it is again arrested. All of the surplus heat above that temperature is consumed in rending the liquid water into moisture globules that float away into the air, each one of them charged with a store of potential energy. Let us follow this vapor spherule as it floats into the upper regions of the atmosphere. Myriads of its fellows travel with it until it reaches a point where condensation takes place, when it collapses and unites with other vapor particles to form water again. In doing this the heat that was expended upon it to disengage it (whether the heat was artificial or that of the sun's rays) now reappears either as sensible heat or as electricity, or both. And this is what is meant in meteorology by latent heat becoming sensible heat at the time of condensation; in fact, it is stored or "potential" energy becoming active or kinetic, and assumes the form of heat or electricity, as before stated. We have thus reviewed the matter of the foregoing chapter in order to follow the course of the stored energy from the melting of the ice to the vapor, and back again to water: to doubly impress the fact that the energy used was not consumed, but still exists and is ready for further work. During the progress of a hailstorm, it has been stated, one of the factors that is active to produce this phenomenon is the intense ascensional force that is given to the moisture-laden air, caused by intense heat at the surface of the earth. This condition forces the moisture vapor to higher regions of the atmosphere than is the case with the ordinary thunderstorm. Another factor that is undoubtedly active in producing hail under these circumstances is that when condensation takes place in the higher regions, and is therefore more energetic on account of the intenser cold, the potential energy that is set free by the moisture spherules takes, in a larger degree, the form of electricity rather than heat, as is the case under more ordinary circumstances. While in the end this electrical energy becomes active heat, it does not for the time being, and thus favors the ready congelation of the condensed moisture into hailstones. Hailstorms are always attended by incessant thunder and lightning, and this fact favors the theory advanced above.