There has recently been a little discussion in these pages on the subject of lightning, some having stated that they discerned the discharge to take place upward—­that is, from the earth toward the cloud.  I will not venture so far as to say whether or not the direction of the discharge is discernible; possibly the flash may sometimes be long enough to enable one to tell; but I have never so seen it, and have always looked upon the eye as a deceitful member—­very.  “The lightning flash itself never lasts more than 1/100000 of a second.”  It is, however, just as likely that a discharge may travel upward as downward.  What controls the discharge?  Does the quality of the charge?—­that is to say, is the positive or the negative more prone to break disruptively through the insulating medium?  Investigations with Geissler’s and other tubes containing highly rarefied gases have made it tolerably clear that there is a greater “tearing away” influence at the negative than at the positive pole, and if two equal balls, containing one a positive and the other a negative charge, be equally heated, the negative is more readily dissipated than the positive.  But, so far as we at present know, this question enters into the discussion scarcely, if at all.  Our knowledge seems rather to point to the substances upon which the charges are collected.  The self-repellent nature of electricity compels it to manifest itself at the more prominent parts of the surface, the level being forsaken for the point.  The tension of the charge, or its tendency to fly off, is proportionately increased.  And if at a given moment the tension attains a certain intensity, the discharge follows, emanating from the surface which offers the greatest facilities for escape.  The earth is generally flatter than the cloud, whence, in all probability, the discharge more frequently originates with the cloud.

Should a lightning flash strike the earth and produce direct neutrality, it is possible that no damage will result, although this again is not always certain, because when the cloud charge acts inductively on the earth it produces the opposite (say negative) charge on the nearer parts, the similar (or positive) state is also produced at some place more or less distant.  Sometimes this “freed” positive (which, by the way, accumulates gradually and physiologically imperceptibly) is collected at some portion of the earth’s surface.  When the negative is neutralized by the discharge, the freed positive is no longer confined to a particular region, but tends to dissipate itself, and a shock may be felt more or less severely by any person within the region.  Or, again, a similar shock may be experienced by a person standing within the negative zone on the neutralization of the charge.