Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

clouds, thus result in a Cumulus; and several cumuli organize into a Nimbus. Then, again, the clouds themselves, if we except the invisible clouds, are distinguished as three grand species or kinds : the Cirri, which have the appearance of loose filaments, and fly the highest; the Cumuli, which are less elevated, have a rounded appearance, and form the large clouds which we see usually accumulated or formed at the horizon, and which we fancy so resemble the gorgeous sight of distant mountains when covered with snow and sunshine ; or as if the looming and ap- proximating of the very land of Beulah. The next are the Stratose clouds, which are horizontal and parallel stripes, or bands, form- ing at sunset, and disappearing again between break of day and sunrise. We observe that when the Cumuli are piled up, and become quite dense, they then pass into the compound state of Cumulo-stratus, which themselves shortly after pass into the state of Nimbi, or true rain clouds. These latter are distinguished by their uniform gray tint, with fine fringe edges ; this, how- ever, soon passes into the uniform, undefmable, and extensive Storm Clouds, which are peculiar for being without visible edges. Thunder clouds are usually formed during the heat of sum- mer days, from the occurrence of a rapid condensation of the vapor with which the atmosphere is then saturated. When this watery vapor, or evaporation from the earth's surface, reaches an elevation where the condensing power of cold (magnetism ?) is sufficient to overcome the repulsive force of the electricity that attends the vapor, then thunder clouds are speedily formed, and the electricity, like latent heat, becomes sensible in the con- densed vapor of that cloud. As the earth is the great reservoir of electricity, so is evaporation the principal and perpetual agent in conveying off the earth's surface electricity so abundantly to and throughout the upper strata of the atmosphere. The evap- oration of the earth's moistures is too extensive to be computed and comprehended, and yet it is this mighty force, that, particle by particle, carries off and up to the sky such prodigious quan- tities of electricity, which particles themselves are rendered all the more volatile by the self-repellent effects of the minute po-