Franklin's kite experiment as described b y him in the well-known letter to Collinson, dated October 19, 1752, naturally challenged the attention of the scientific world and established the electrical nature of lightning. Efforts to get accurate dates and details have proved unavailing thus far, although it would seem that in contemporaneous journals and correspondence some corroborative evidence must exist.
The common belief that the kite experiment paved the way for the introduction of the lightning rod is disproved by Franklin's own use of the rod and his clearly expressed views as to the identity of lightning and electricity, at earlier dates.
Perhaps the most promising method of obtaining knowledge of the nature of lightning is the duplication by artificial means of high voltage discharges having considerable current and very steep wave fronts. Such work is now carried on by the General Electric Co. in its high tension laboratory at Pittsfield, Mass., under the direction of Mr. F. W. Peek, jr. These discharges may well be called near-lightning, and illustrate well the peculiar characteristics of the natural discharges whether we regard them as oscillatory or unidirectional.
There has been a tendency in scientific circles to depreciate the importance of this line of attack and to give preference to values obtained on theoretical grounds and measurements which seem open to criticism. Attention is called to an error in a published statement critical of our estimate of the energy of an average flash; and it is shown that confusion has arisen from the use of units with similar initials but quite different values.
Some approximate measurements of the energy in kilowatt-hours are given, based upon fusion of kite wire at Blue Hill Observatory, and the voltage is shown to be of the order of 13,000,000 as compared with 10,000,000,000 given by so eminent an authority as C. T. R. Wilson. Kite experiences at a number of Weather Bureau stations are summarized as confirmatory of the lower values.
The importance of a study of the side discharges or split-off flashes is urged as contributing to a knowledge of the process of breakdown of the dielectric, the origin of the path, the concentration of electrons producing ionization, and the nature of the explosive effect.