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

floor, he was struck in his head and killed instantly. Lightning and thunder, then, is but a simple discharge of electricity, only on a large and magnificent scale. Clouds. We may notice, without the weather being decidedly stormy, that the very presence, in the otherwise serene atmosphere, of a small or thin, fine cloud, or of the fall of a few drops of rain, or a few flakes of snow, is sufficient to modify the normal state of electricity in the air. But this is far from possessing the im- portance that results from the existence of a storm, a dense fog, or thunder and lightning, with wind, rain, hail, or snow. The mere formation of a single cloud, or of the slightest fog, is accompanied with a sensible disturbance of the electric state of that stratum of air in which this formation takes place. Tbe aqueous vapor with which the atmosphere is always more or less saturated, being usually invisible, becomes in the clouds and fogs visible ; and we know that their globules are so many small spherical balloons, in which a small capsule or pellicle of water serves as an envelope to the interior air, which is polarized. We have only to place an electroscope in the middle of a cloud, or fog, when driven by the wind, and we see how greatly the di- vergence of the needle varies with the passage of the successive flakes of denser portions of the fog or cloud. Now, to understand in some degree those wonderful electric phenomena of clouds over and about us, and which are so full of meaning, it is well, and indeed necessary, to be more familiar with the individualities of each of the globules of which they are composed. But this must not be entered upon here. I will only remind you, that the globules themselves are grouped by small flakes, which have their limits and their spheres of action, much like the globules themselves; the small flakes, by grouping, con- stitute the large flakes ; the latter group and form Manilla; a certain number of these again, by their reunion, form a Cloudlet ; and the cloudlets marshal by a law into given definite clouds ; and these again, grouping as so many individual and definite