ing stars were seen moving from an altitude in the N. E., of about 20°, to one in the S. E. of from 450 to 60°; and with flights, from the quarter first mentioned towards that last mentioned, of from 20° to 40° in length. Though the directions were uniform, the meteors finshed their flight at very different distances from the starting point in the N. E. Many drew trains after them to the termination of their course, where they burst into sparks; and so close was the resemblance to rockets that the sound of the bursting could be almost heard. The time of flight was two or three seconds. The meteors (the larger are probably intended) were not more frequent than perhaps two in a minute; but several small ones might be seen shooting at the same time. They were visible only in the quarter of the heavens from the N. E. to the S. E. The wind all night was N. E., and the ship's course steady-standing for New York. Upon coming on deck, at 4 A. M., our informant found by enquiry that the display had lasted through the night. The meteors still continued visible in very small numbers-only a few in an hour-till day. Capt. Briggs has never, at any other time, seen a similar display.

This twice repeated co-incidence, in the month and day of the month, as it has been remarked already, would make further doubt respecting the celestial origin of the meteors irrational, but for a limitation not to be neglected ;-namely, the necessity of ascertaining, before we adopt an hypothesis in full, that it will certainly explain all the phenomena. The whole question has, by this time, reduced itself to an astronomical problem, resting upon several conditions. -We shall state the conditions, without knowing whether they can be fulfilled or not. This want of knowledge is occasioned by a twofold cause, and is in part unavoidable and in part voluntary. It is in part unavoidable; for the writer has no time, at present-if he have the ability-to attempt so complicated a problem: it is also in part voluntary; for some of the most important conclusions of this paper rest upon the discussion of probable evidence; and in such a case it is better that the mind feel its way, without a theoretical guide to tempt it to stray from the path of rigid and impartial investigation. It is upon direct evidence that our conclusions have restedwhether in the case of facts which are unquestionable, or such as are only highly credible, and we put down the problem and its conditions as we conceive them, without having any concern, at present, about the possibility of a consistent solution. But if a consistent solution shall come to light, then indeed the writer will not hesitate to adopt

in full a hypothesis, respecting the cause of the meteors, based on the general principles which have been already advanced. But to proceed to a statement of the conditions of the problem.

It is required so to arrange a system, or cloud, of meteoric bodies in an orbit around the sun that it shall, at stated periods, encounter the earth; and that the disturbing force of the latter shall draw a part of them only from their orbit; and give to them such motions.

as to account

1st. For the appearance of the meteors, in small numbers, early in the evening of Nov. 12th;

2d. For the stationary situation of the radiant, for two hours at least, on the morning of the 13th-and its observed position in the heavens ;

3d. For the change of declination, relatively to a change of latitude-while the position in right ascension was unvaried;

4th. For a relative velocity of the meteors, of from about 14 to 20 miles a second;

5th. For an eastward motion of the whole meteoric shower, equal to the velocity of the earth's rotation, for a part of the time at least of its duration as observed in different years and places, by Humboldt, Capt. Parker and Capt. Briggs;

6th. For a duration of the meteoric shower, less than a day, at the

utmost.

Final Obs.-When we glance back upon all the known circumstances of the meteoric shower, the extent and magnitude of the powers in exercise fill the mind with wonder. The one body whose flight we have been able to calculate, and which moved with such inconceivable rapidity, could not have been less—after allowing for the deceitful glare of surrounding and enveloping flame-than a hundred feet in diameter; and doubtless very many others were as large. The multitude of bodies was such as no man can venture with confidence to limit by numbers; and, had they held on their course unabated for three seconds longer, half a continent must, to all appearance, have been involved in unheard of calamity. But that Almighty Being who made the world, and knew its dangers, gave it also its armature-endowing the atmospheric medium around it with protecting, no less than with life-sustaining properties: and, considered as one of the rare and wonderful displays of the Creator's preserving care, as well as the terrible magnitude and power of his agencies, it is not meet that such occurrences as those of Nov. 13th, should leave no more

solid and permanent effect, upon the human mind, than the impression of a splendid scene. To return, however, to our immediate subject and its connexion with the cause of human knowledge:we may well regret that, with so much to be known apparently within our reach, so little that is definite should be, as yet, disclosed. Yet the success-partial though it be-which has rewarded the few investigations which have been perseveringly made, yields an inducement to more systematic effort; and we trust that individuals who have the time at command, will deem it, even now, a labor well bestowed, to rescue from oblivion any one well ascertained fact respecting these wonderful phenomena.

ART. IX.-Communications by Dr. HARE.

1. Description of a process, and an apparatus, for Blasting Rocks, by means of Galvanic Ignition.

Remark. That portion of this article which precedes the first cut, was published in this Journal (Vol. xxi. p. 139.)-but, it is thought best to republish it now in connexion with the additional illustrations, rather than give the reader the trouble of looking into the separate volumes.-Ed.

I have observed various accounts in the newspapers of workmen killed or dreadfully lacerated, by the blasting of rocks.

This, and many like occurrences will, I presume, create sufficient interest in the following communication, to justify its appearance in the American Journal of Science.

I have ascertained that by a new application of galvanism, rocks may be riven with less danger than that which attends the firing of a pistol. I was induced to attempt this improvement in consequence of an application by a patentee (Mr. Moses Shaw,) for assistance in perfecting his patented mode of blasting rocks, by an electrical discharge from a Leyden jar.

In a letter dated June 1st, 1831, he says, "I have been engaged in blasting rocks by means of a fulminating powder, introduced into several cavities, and ignited in all of them simultaneously, by a spark from an electrical machine, by which means masses of a much larger size, and of a much more suitable shape, for any object in view, may

be procured, than by the old plan. I have, however, to lament my inability to succeed in this method of blasting, during a great part of the year, when, in consequence of the unfavorable state of the weather, the ignition cannot be effected by electricity in any mode which I have devised, or which has been suggested by others, although I have consulted all the best informed professors to whom I have had access."

It occurred to me, as soon as this statement was made by Mr. Shaw, that the ignition of gunpowder, for the purposes he had in view, might be effected by a galvanic discharge from a deflagrator, or calorimotor, in a mode which I have long used in my eudiometrical experiments to ignite explosive gaseous mixtures. This process is free from the uncertainty, which is always more or less attendant upon the employment of mechanical electricity, for similar pur

poses.

The expectation thus arising, has since been fully verified. I have ignited as many as twelve charges of gunpowder at the distance of one hundred and thirty feet, from the galvanic machine employed. This distance is much greater than is necessary to the safety of the operator, as the deflagrator may be shielded so as not to be injured by the explosion, and by means of levers and pulleys, it may be made to act at any distance which may be preferred. There is no limit to the number of charges which may be thus ignited, excepting those assigned, by economy, to the size of the apparatus employed.

These remarks have reference to the principal and highly important object of Mr. Shaw's project, which is to ignite at once a great number of charges, in as many perforations so drilled in a rock, as to co-operate simultaneously in the same plane. By these means it is conceived that the stone may be separated into large prismatic, or tabular masses, instead of being reduced to irregular fragments of an inferior size. The object to which I propose now to call attention more particularly, is a modification of the common process of blasting by one charge, which renders that process perfectly safe.

This part of the subject I shall introduce by premising, that almost all the accidents which have taken place in blasting rocks, have occurred in one of the three following modes:

1st. The explosion has taken place prematurely, before the opera

tor has had time to retire.

2nd. A premature explosion has ensued from a spark produced by the collision arising from ramming into the perforation, containing

the powder, the brickdust, or sand, or other matter, employed to close it.

3d. The fire not reaching the charge after the expiration of a period unusually long, and the operator returning to ascertain the cause of the supposed failure, an explosion ensues when he is so near as to suffer by it, as in the instance near Norristown, published some years

ago.

The means of communicating ignition, to which I have resorted, are as follows:

Three iron wires, of which one is of the smallest size used for wire gauze, the others of the size (No. 24,) used by bottlers, are firmly twisted together. This is best accomplished by attaching them to the centre of the mandril of a lathe, which is made to revolve while the other ends of the wires are held by a vice, so as to keep them in a proper state of tension. After being thus twisted, a small portion is untwisted, so as to get at and divide the larger wires by means of a pair of nippers. In this way the smaller wire is rendered the sole mean of metallic connexion between the larger ones. These are tied in a saw kerf, so made in a small piece of dogwood as to secure them from working, which, if permitted, would cause the smaller wire to break apart. At one end, the twist formed of the wires is soldered to the bottom of a tin tube of a size to fill the perforation in the rock to such a height as may be deemed proper. This tube being supplied with gunpowder, the orifice is closed with a cork, perforated so that the twisted wire may pass out through it without touching the tube at any point above that where the finer portion alone intervenes. To the outside of the tube, a copper wire, about No. 16, is soldered, long enough to extend to a stout copper wire proceeding from one of the poles of a galvanic deflagrator or calorimotor. The wire passing through the cork from the inside of the tube, is in like manner made to communicate with the other pole. The connexions between the wires and the poles, should be made by means of soft solder, previously to which we must imagine that the tube has been introduced into a perforation made for its reception in a rock to be blasted. The tin tube may be secured within the rock by the usual method of ramming in brickdust or sand, by means of a plug, having holes for the protection of the wires of communication already described.*

* It has occurred to me that plaster of Paris might be used advantageously, as it would require no ramming, and might set with sufficient firmness.