Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.
56/740

one exception, for an equal number of cloudy and clear days, was met with to this rule, viz., in July; the electricity on the cloudy days was 41, on the clear days 35. 4. As regards fog, snow, and rain, it was observed that the amount of electricity was the same during the two former states of weather, and was double that observed during rainy weather — the latter corresponding to the minimum of the annual elec- tricity, the former to the maximum of the year. 5. As to the Kind of Electricity in the Air.—It was noted that during a period of five years, only twenty-five observations gave evidence of resinous or negative electricity; the rest con- sisting of eighteen hundred observations, which indicated vit- reous or positive electricity. The negative observations were all recorded after storm or rain, or some other great meteoro- logical change. The normally electrical state of the atmosphere may therefore be considered as positive. 6. Wind. —It was observed that when the wind was E. S. E., or S. E., two maxima were regularly formed, and two minima when at W. S. W., and that these corresponded with the other variations which have been mentioned. 7. The diurnal variations were recorded during the same period of five years, from six o'clock in the morning until nine at night. The degrees of divergence showed that there were two maxima and two minima daily. The maxima were at 8 A. M., and from 8 to 9 P. M., in opposite periods to the magnetic maxima. One minimum was from 2 to 4 P. M.; the other, prob- ably, during the early morning hours. All these great and regular phenomena of the atmospheric electricity, Dr. Faraday observed, are phenomena of static elec- tricity, while the thunder storm, the St. Elmo light, &c, &c, are exceptional instances of current or dynamic electricity; not necessarily, however, requiring clouds for its concentration or evolution. The professor concluded by expressing his dissent from the theory of M. Quetelet, that the electricity of the earth was neg- ative, and that of planetary space was positive. According to this theory, the only true electricity is what we call negative;