pression, and the angle OML is the complement of HOP'. O being the centre of the circle of the horizon, and G that of the limiting circle, the depression enables us to find OL, GL. MLOL. tan MOL; and GM = GL2+ML2. Also, angle GML is easily found. Now the three planes make a solid angle at M, of which one of the containing plane angles (OML) is known, and also two of the inclinations; whence the angles QMO and QML may be ascertained. Also, GMQ=GML+ LMQ: consequently, if a perpendicular, GL', be dropped from G on MQ, its length may be found, and also the ordinate QL', and the line L'M: whence QM is known. OM is found in the triangle OLM: and therefore, in the plane triangle OMQ, we have OM, MQ and the angle OMQ, from which to obtain the angle MOQ. This, and the known inclination of the plane OMQ to the horizon, enable us to determine the apparent altitude of Q.

This method has been applied to determine the aspect of the light as it would, under this supposition, appear in this latitude, at the close of twilight, when the inclination of the ecliptic to the horizon is at its minimum. The arch would follow the course of the ecliptic, from a point on the horizon 31° 20' distant in azimuth from, the vertical passing through the sun, one hundred and forty-one degrees. The highest point of the arch would be 32° above the horizon, and the extremity of the light would have an apparent altitude of 1940. There would also be a trace of the opposite cusp, rising about 20 from the horizon. This being the appearance under the circumstances least favorable to visibility, at all other times both cusps ought to be seen, both morning and evening, throughout the year; and one of them ought always to have an enormous length when the sun is within 180 of the horizon.

These results being optical and geometrical necessities consequent upon the hypothesis of a nebulous ring surrounding the earth and illuminated by the sun's light, and being all of them unconfirmed by observation, it seems impossible to arrive at any other conclusion but that the hypothesis is untenable.

We appear, therefore, to be conducted to one and the same conclusion by the application to this theory of four distinct tests; each one of them having no slight independent weight, and all of them combined possessing an irresistible force. The zodiacal light must consequently be regarded as presenting a problem still unsolved. The observations of Mr. Jones, when published, may possibly present some clew to the mystery which has not yet been detected in them. But whatever else they may show, the present writer cannot but believe that they will furnish, in them

selves, most conclusive proof, that the luminosity does not reside in any substance physically connected with the earth.

Upon the whole, whatever difficulties may attend the theory which regards the zodiacal light as having its seat in some appendage of the sun, there seems to be as yet no other supposition possessed of greater plausibility.

University of Mississippi, Oxford, Oct. 30, 1855.

ART. XXVII-On the Recent Eruption of Mauna Loa; by Rev. T. COAN.*

It is now ninety-seven days since the great valve opened on the mountain, and still the volcano works with unabated energy, pouring out its floods of fire in ceaseless torrents. Long ago we had expected to witness the molten sea sweeping over our fields, choking our harbor, driving our ships from their moorings and our citizens from their homes. But though the igneous flood still approaches us, its approach is so slow that our fears are greatly allayed. Reasoning mathematically, and assuming that the high fountain remain in force, the future terminus of the stream must be the seas; thus it is only a question of time.

After returning from the mountain, and having rested and attended to necessary duties, I determined to cut through the jungle to the lower end of the stream. Several natives had been up and reported the fire as making its way toward us, like the dogged and slow approaches of the allies before Sevastopol; but no white man had penetrated the jungle. On the 31st of October Mr. Ritson, an English gentleman, and myself, with three natives, entered "the bush," and beat our way through mud and jungle, until we came to a large and rapid tributary of the stream called Wailuku. Up this stream we wended our way with incredible toil, wading for miles together in water from one to three feet deep and along an uneven bottom of slippery stones, crossing and recrossing scores of times, to avoid rapids, deep basins and cataracts, slipping, falling, and plunging along, and when reaching an impassable basin, rapid, or precipice, crawling up the bank and beating slowly through the wet and entangled jungle, until the obstructions in the stream were passed, and then tumbling down again into its tortuous bed. Thus we urged our toilsome way under a drenching and continuous rain, at the rate of from one half a mile to one or two miles an hour, as obstacles were more or less serious.

* From a letter to Rev. C. S. Lyman, dated Hilo, Nov. 16, 1855. This account is in continuation of that published in the last number, page 139.

So soon as we entered this stream we found it discolored with pyroligneous acid from burning wood, whose odor and taste became more and more positive the farther we advanced up the stream. The discoloration also became more apparent as we proceeded, until the water was almost black. This showed that the lava flow had crossed the head waters of the stream and its small tributaries, consuming the forest and jungle, and sending down what could not be evaporated of the juices to mingle with the stream.

A little before sundown, our guide led us at right angles from the stream we had been threading for six hours, and in a few minutes the fires of the volcano glared upon us through the woods. We were within six rods of the awful flood which was moving sullenly along on its mission towards Hilo. The scene beggared description, and for a moment we stood mute and motionless. Soon, however, we moved on to the verge of the igneous river. Thrusting our poles into the fusion, we stirred it and dipped it up like pitch, taking out the boiling mass and cooling all the specimens we desired. We were on the right or southern verge of the stream, and we also found that we were about two miles above its terminus, where it was glowing with intense radiance and pushing its molten flood into the dense forest which still disputed its passage to the sea.

We judged the stream to be two or three miles wide at this point, and over all this expanse, and far as the eye could see above, and down to the end of the river, the whole surface was dotted with countless fires, both mineral and vegetable. Immense trees which had stood for hours, or for a day, in this molten sea were falling before and below us, while the trunks of those previously prostrated were burning in great numbers upon the surface of the lava. It is impossible to give you any just conception of the scene.

You are aware that the great fire-vent on the mountain discharges its floods of incandescent minerals into a subterranean pipe which extends, at the depth of from 50 to 200 feet, down the side of the mountain. Under this arched passage the boiling fusion hurries down with awful speed until it reaches the plains below. Here the fusion spreads out under a black surface of hardened lava some six or eight miles wide, depositing immense masses which stiffen and harden on the way. Channels, however, winding under this scorified stratum, conduct portions of the fusion down to the terminus of the stream, some 65 miles from its high fountain. Here it pushes out from under its mural arch, exhibiting a fiery glow, across the whole breadth of the stream. Where the ground is not steep and where the obstructions from trees, jungle, depressions, etc., are numerous, the progress is very slow, say one mile a week.

On the evening of our arrival we encamped within ten feet of the flowing lava, and, as before stated, on the southern margin of the stream, some two miles above its extreme lower points. Here, under a large tree, and on a bank elevated some three feet above the igneous flood which moved before us, we kept vigils until morning. During the whole night the scene was indescribably brilliant and terribly sublime. The greater portion of the vast area before us was of ebon blackness, and consisted of the hardened or smouldering flood which had been thrown out and deposited here in a depth of from ten feet to one hundred.

Not only was the lava, as aforesaid, gushing out at the end of this layer, but also at its sides. These lateral gushings came out before and behind us, and two-thirds surrounded our camp during the night, so that in the morning, when we decamped, the fusion was just five feet, by measurement, in front of us, six feet in our rear, and three feet, or the diameter of the trunk of our camp-tree, on our left. The drenching rain and our chilled condition induced us to keep as near the fire as we could. bear it. Evening and morning we boiled our tea-kettle and fried our ham upon the melted lavas, and when we left, our sheltering tree was on fire. A large tree fell within ten feet of us during the night. Often, too, would the dried vines, parasites and leaves of immense trees take fire and running up to the height of seventy or eighty feet, throw off countless scintillations which sparkled and glanced amidst the gloom like myriads of fire-flies. But another exhibition exceeded all the rest in interest. At thousands of points on the solidified crust of the stream, the accumulating fusion, fed from above, was swelling and raising this superincumbent stratum into tumuli of endless form and size, and then, bursting open the cone or dome thus raised, either laterally or at the apex, when flowing off for several rods over the old substratum, the stiffening flood became solid. Soon, perhaps, another layer is spread upon this, and thus on indefinitely, until thirty or forty strata may be deposited in succession, raising the whole from a few feet to fifty or one hundred in thickness, and presenting a heaving surface like an agitated sea suddenly solidified. Thus the deposits become enormous, the fusion spending itself, and thus retarding its progress towards Hilo.

The whole breadth of the lava stream lies between the river Wailuku whose course is east, and one of its largest tributaries which flows from the southwest. As we have said, this branch was our route by which we threaded our way to the fires, the lava stream lying within half a mile of its banks, at the place where we left it, and having fallen into its head waters above us. An effort to cut across below the lava stream was made that we

might get a more definite idea of its width, that we might obtain a front view of it, and, finally, that we might reach the channel of the Wailuku and descend in it to Hilo, the passage along this stream being much easier than in the branch by which we had reached the fire. Previous to our efforts to cut through the woods from one stream to the other, we had made an attempt to cross directly over on the lava stream itself. This we tried first directly from our camp; but failing here, we beat our way through the thicket up the verge of the stream, hoping to find a point where the fires were less active.

At length we made another effort to cross. But the hardened surface of the stream was swelling and heaving at innumerable points by the accumulating masses and the upraising pressure of the fusion below; and valves were continually opening, out of which the molten flood gushed and flowed in little streams on every side of us. Not a square rod could be found on all this wide expanse where the glowing fusion could not be seen under our feet through holes and cracks in the superincumbent stratum on which we were walking. The open pots and pools and streams we avoided by a zigzag course; but as we advanced, these became more numerous and intensely active, and the heat becoming unendurable, we again beat a retreat after having proceeded some thirty rods upon the stream. It may seem strange to many, that one should venture on such a fiery stream at all, but you will understand that the greater part of the surface of the stream was hardened to the depth of from six inches to two or three feet; that the incandescent stream flowed nearly under this crust like water under ice, but showing up through ten thousand fissures and breaking up in countless pools. On the hardened parts we could walk, though the heat was almost scorching, and the smoke and gases suffocating. We could even tread on a fresh stream of lava only one hour after it had poured out from a boiling caldron, so soon does the lava harden in contact with the air. Finding no way to cross the igneous flood, and the rain falling in torrents, our guide admonished us that we must hasten back, as the water course up which we came was rapidly filling. We therefore reëntered the channel at ten A. M., and found the stream so swollen and so grand in its wild rushings and plungings, that it was with the greatest difficulty and danger we effected a retreat. Mercifully we reached home, scorched, smoked, exhausted, and "water-logged."

Nov. 20th.-Three different parties have returned from the fire since this letter was commenced. It has made two miles progress since my return and it is estimated to be within eight miles of the shore. Notwithstanding the winding and difficult way, one can now go up, dip up the fusion, and return the same day.