The Journal of Science, and Annals of Astronomy, Biology, Geology ...

very comprehensive manner, and is especially powerful in treating on the geological portion of the question.

In April, 1882, the present writer published a small work on "The Action of Lightning," completed by him in April, 1881. He was unfortunately unaware of the researches concerning the association of electricity and earthquakes made by the authors he has mentioned, or the short allusions made to the subject in his work would probably have been more copious and decided. He ventures, however, to resubmit these few references as being perhaps entitled, in their measure, to take part as links in the chain of literary effort under investigation. The passages are as follows:"We appear to have prima facie grounds for believing that the earth's surface is really the collecting plate of the terrestrial condenser; . . . but the questions now arise, what is the original source of the earth's electricity? and how does its surface collect it? In our present state of knowledge it seems to be impossible to get beyond conjecture in replying to such questions. Supposing, however, that we take up the opposite view, that the clouds form the collecting plate, the task of attempting to prove how they originate and collect their electricity would appear to be even more hopeless; for although we reasonably infer that the clouds are collectors of electricity, we do not know the fact for certain. . . . But we do know with certainty several important facts regarding the earth's electrical constitution; one is that it is a great holder of electricity; . . . another, that terrestrial disturbances, such as waterspouts, earthquakes, and volcanic eruptions, are connected with the actions of electricity or magnetism." . . . "As to how the earth... became a magnet we are practically in total ignorance. The fact, however, that it is simultaneously both a holder of electricity and a magnet is well worthy of attention; and so also is the fact that phenomena undoubtedly electrical, i.e., earth-currents and auroræ, are invariably accompanied by magnetic disturbances." May we not conceive the subtle force usually called magnetism to be nothing but electricity, i. e., electricity bound or manifested in a peculiar manner, and magnetism itself as only a property or influence... appertaining to certain bodies and permitting this particular manifestation?"... "On this principle, then, the earth is a magnetic body like steel or iron, and what is known as its magnetism becomes an additional proof of the presence and activity of its electricity, and strengthens the probability that the globe is itself the originator of thunderstorms and of all other electrical phenomena

known to occur in connection with it. That the separated agencies composing this electricity should be in constant motion in the magnetic field or orb from the Equator towards the Poles is what is to be expected; . . . hence . we have manifestations of motion (rendered irregular by induction and by geological causes) in the shape of earthcurrents. The polar accumulations of electricity. . . would explain the attraction of the earth's poles on those of other magnets. To the same fact of dense accumulation of electricity at or near the magnetic and terrestrial poles . . . would be attributed the manifestations of silent continuous discharges . . . seen under the form of aurora. And it is conceivable that the electricities, in their motions . . . towards the poles, are occasionally forced . . . to accumulate for a time at certain places on the surface; and when this should occur in regions where clouds . . . were frequently present, the necessary conditions for the development of thunderstorms would apparently be obtained. Lastly, if the . . . accumulations should occur in certain portions of the earth's crust . . . insulated from each other, and below though not far removed from the surface, and especially in regions where clouds . . . were habitually absent (as in Chili and Lower Peru), there would appear to be possible causes for the occurrence of earth explosions manifested by earthquakes" (pp. 156-160). In regard to the term explosion here used the writer is now inclined to consider the nature of an earthquake discharge as an electrical leak rather than as an electrical explosion.

In the "Athenæum " of July 8th, 1882, a review of the last-mentioned work was given. The reviewer noticed the portions relative to terrestrial electricity in the following terms:-"The earth-sprung lightnings which so constantly form an attendant phenomenon on volcanic eruptions, and the subterranean thunder which at times resembles the artillery fire of a naval engagement, are at once facts that support the view given in this book of the functions of the terrestrial condenser, and hints that the diligent pursuit of the enquiry may yield much valuable information as to the general theory of electric storms, aërial, super-terrestrial, or sub-terrestrial." .. "It is from the co-ordination of the indications given by the barometer, the seismometer, and the various appliances for measuring electric and magnetic force and direction, that we must hope to arrive in due time at the true theory of electric storms, of which we take thunder and lightning to be one form and earthquake another."

The last extract in our series is one from an article on "The City of Earthquakes," in the "Atlantic Monthly Magazine" for March, 1883, by Mr. Horace D. Warner, a Civil Engineer who was present at Caracas during the last earthquake there, on September 6th, 1882. It appears that it was accompanied by a coast wave, and that serious damage was almost wholly confined to the river suburb, the higher portions of the town, built on a rocky substratum, being untouched. He says that "a native of Venezuela would laugh at the idea that a terremoto is an upheaval of the ground. The movement of dislodged rocks, the disjointment of house-walls and their way of falling, the motions of a tidal wave during the progress of an earthquake, all prove that the shock is a lateral push." This statement seems to corroborate the idea already suggested, in reference to the writings of Mr. William Nicholson in 1787, that the shock is probably a discharge not of the concentrated nature of an explosion, but rather that due to a sudden escape of accumulated force from the ground over an area of some extent,-a theory to which the facts attendant on electrical leak discharges are eminently favourable.

In order to strengthen the idea of the electrical origin of earthquakes we will now submit a list of some of those events the records of which show that they were preceded, accompanied, or followed, by storms of thunder and lightning. The incidents, unless otherwise annotated, are selected from Mallet's Reports.

Accompanied by Thunderstorms (45 cases).

1606 (B.C.). Mount Sinai. 1117. Jan. Upper Italy.

365 (A.D.). July 21. Greece 1117. May. Liège.

and Asia Minor.

1138. Wurzburg.

The year 1750-during which, on September 30th, the shock at Daventry, in Northamptonshire, occurred-was remarkable for thunder and lightning throughout England (Priestley, Hist., 356). In 1822 "an extraordinary number of violent thunderstorms, accompanied by earthquakes and simultaneous eruptions of Mount Vesuvius," occurred in France and over a great part of the Continent (Anderson on Lightning, p. 76). In July, 1829, earthquakes occurred in Hungary and in Spain, and remarkable thunderstorms in many parts of Europe (Mallet). In 1880, and again in 1883, thunderstorms and earthquakes were very prevalent in many countries.

Followed by Thunderstorms (22 cases).

1622. March. Upper and 1628. Mecklenburg.

Lower Engadine.

1626. Sept. 6. La Capitanata and Naples.

1661. March 27. The Valais, Switzerland.

1662. September. Rome.

1785. July 19. Coldstream, Berwickshire. (Phil. Tr., lxxvii.)

1864. August 21. Lewes, Sussex. (B. A. R., 1864, Trans., 16.)

1810. Nov. 29. H.M.S. Salsette, 10 leagues S. of Cape Matapan, Mediterranean Sea. (Edin. Journ. Sc., 1826, v., 222.)

1883. July 28. Ischia, Bay of Naples. A violent thunderstorm at Naples on July 29th. (Times, July 31, 1883.)

To the above lists it may perhaps be interesting to add a few meteorological statistics, gathered from the records of earthquake incidents, collected by the writer for analysis, up to the present date. Most of the manifestations named are probably closely connected with the action of terrestrial electricity. It is to be understood that either shortly before, or during, or shortly after the occurrence of shocks, these additional phenomena were among the attendant circumstances. The number of separate earthquake cases from which they are gleaned amounts to 490.