THE PAST,-A REVERIE.

I MUSE, and lo! upon my thoughtful view,
A city rises, beautiful and new;

High tow'rd the skies is lifted many a dome,
Where living glories seem to make their home:
The hum of men each busy street pervades,-
The laugh of pleasure rings from garden shades:
Proud chariots roll along unnumbered roads,
Where wealth goes forth to seek the calm abodes
Of rural luxury, and tranquil ease,

Where slumbers soothe, or gilded baubles please.
Joy smiles on every scene: the goblet fair,
In mantling blushes, circles freshly there.
Morn wakes on early revelries begun,-
On wildering riot glares the setting sun;-
And the stars, flashing in the depths of heaven,
Look down on feasts that vex the hush of even:
gaze till sense, and thought, and love are won,-
I breathe in transport,-"This is Babylon!'

I

The scene is changed, and by a lonely shore, Which silence dark and dim reposes o'er,

I stand,-a Pilgrim, in a dreary waste,

Midst crumbling battlements, and shrines defaced :

A river, moaning on the dusty plain,

Rolls dark and sinuous to the distant main :

In gloomy cadence, rustling sadly round,

The slow, green lizard creeps along the ground;
The drowsy bat his dreary flight sustains,
Or 'neath some broken arch, his nest regains:
Where a deep sadness lingering seems to brood,
More hushed than night-more deep than solitude.
I ask of History's Muse-her voice replies,-
'Lo! the Chaldean's pride before thee lies!
This was the glory of that mighty race,-
Mark thou the darkness of their dwelling place!

Here did their fanes and temples proud aspire,

Here smiled their domes in sunset's floods of fire,Here mirth and lust, here pride and power held swayBehold the remnants of their swift decay!

Earth owns one mighty power-one sway sublime-
Kings are its play-things-'tis the might of Time!

'If the deep lessons graven on the waste,
Or wrecks of grandeur all around thee placed,
Have not a potent charm to win thine eye,
And fill thy heart with deep morality,
Lo! where the glories of luxuriant Tyre
Like the bright pageants of a dream expire!
Once o'er the ocean swept her broidered sail,
Fanned by the prosperous Egyptian gale;
All nations, from the affluent climes of old,
Did in her open lap their wealth unfold :
The gold and spicery of the eastern land,
Gave up their gleams and sweets at her command.
Now gaze where darkling and in wrecks she lies,
Fretted by billows that around her rise:

The murmuring floods have broken on her shore-
Tyre is an hissing'-she will bloom no more!

If thou wouldst ask for other shrines and forms, Where faded years have passed in clouds and storms, Look to the islands of the Egean sea,

Where swelled of yore the shouts of victory:

Where mighty Athens once, in arms and arts
Usurped the homage of all human hearts.
How have the ravage and the blight of Time
Swept o'er her altars, and her piles sublime!
The lonely Troad spreads its lengthened shore,

And the waves moan of Greece,fair Greece no more :
No more shall heaven unveil its rising sun

On scenes like Leuctra, or like Marathon ;
No more shall Sappho wake her mournful lyre
Or sightless Homer sweep his chords of fire
Leucadia's rock and Scio's isle no more
Shall wear the lustre that of old they wore :
The Bard and Lover sleep in dreamless rest,-
The clod weighs heavy on each wasting breast;
And she, whose numbers melted o'er the wave,
Hath gone with broken hopes, to fill a grave.
Theirs are the slumbers, man can never break-
Theirs the deep trance, no praises e'er may wake;
Their breathless hush no plaudits can disturb,-
Earth folds the passions that have found a curb:
Eyes, once illumed with love, in night are hid,
'Neath the thick vesture of the coffin-lid!'

Yet who can mark the glory and the glow,
Which deathless Fame can to the dead bestow,-
Who can look down on reverend ashes blest,
Nor love the Muse, which sanctifies their rest,-
Whose spell a halo o'er the grave can pour,
And scatter sunbeams on Death's cloudy shore!
Philadelphia.

G. G. B.

ATMOSPHERIC ELECTRICITY.

BY THE AUTHOR OF 'A NEW THEORY OF MAGNETISM,' 'MOLECULAR ATTRACTIONS,' ETC.

WHAT is atmospheric electricity, or lightning? Whence its origin? and what is its agency in the production of atmospheric phenomena? These are questions which have agitated Philosophers from the days of Dr. Franklin to the present time, without receiving any satisfactory solu tion. Surprising as this statement may appear to the general reader, an examination of the latest works on Natural Philosophy, published in France, England, Germany, and the United States, will demonstrate its truth. This subject has recently occupied the attention of Philosophers in Europe, more than any other branch of Physical Science.

In the article on Molecular Attractions, in a late number of this Magazine, we stated, in general terms, that caloric and electricity are only different forms and modifications of the same subtile element which pervades the universe, and gives to it all its motions, mechanical, chemical, and physiological, that the latent caloric of all bodies is convertible into heat or electricity, according to the mode of its disengagement from

other matter.

However new and startling this doctrine may seem, we shall endeavor to establish it by an appeal to meteorological facts:

1. Dr. Dalton, of Manchester, demonstrated by experiment, that caloric is the only cause of evaporation. He put a little water in a dry glass

flask, with a thermometer in it, when he found that a small quantity of vapor was formed at 32° Fahrenheit. At 40°, the quantity of vapor was increased at 50° it contained still more; while at 60°, the quantity was still further augmented. He also found that when the temperature of the flask was suddenly reduced from 60 to 40 degrees, a portion of the vapor was converted into water; and that the quantity retaining the elastic form was precisely the same as when the temperature was originally at 40 degrees.*

2. The attraction of caloric for water causes it to enter into, and expand its particles, by which it is carried into the atmosphere in the form of invisible vapor; while the affinity of the same caloric for bodies which contain less of it, draws the vapor towards them, and its heat is abstracted, when they descend in rain, snow, or hail, according to the season, or prevailing temperature of the atmosphere. When cumuli of clouds are formed in the atmosphere, by giving out a portion of their heat to colder bodies, they are minus or negative, in relation to all uncondensed or transparent vapor, which is plus,-so that they become centres of attrac tion, drawing to them successive masses of invisible vapor, and abstracting their caloric, by which a perpetual condensation is kept up, until they become aggregated into extensive masses, which often resemble huge castles, or vast rocky mountains, suspended in the air. The attraction of caloric for ponderable matter, causes evaporation at all temperatures, increasing from 0 up to 2122-and if the pressure of the atmosphere be removed, it will go on at 50, or 100 degrees below zero. According to the experiments of Dr. John Robison, of Edinburgh, the boiling point of liquids is reduced about 145° in a good vacuum. Water boils at 67°, and alcohol at 28°. When the receiver becomes full of vapor, its pressure or elasticity prevents the further process of evaporation; but if sulphuric acid, or some other substance having a strong affinity for the vapor, be introduced, the vapor is absorbed as fast as formed; so that the surrounding heat continues to be attracted by the liquids, and converted into vapor, until the temperature falls below the freezing point of mercury. In this way, a greater cold may be produced than by freezing mixtures, the rationale of which is the same in both.

3. When the atmosphere is already full of aqueous vapor, it presents a mechanical impediment to the further passage of air through it, which enables us to comprehend why it is that cold air when dry, promotes evaporation better than warm air, which is full of aqueous vapor. In this last condition of the atmosphere, the slightest reduction of temperature causes a condensation of the transparent aqueous vapor into mist, clouds, rain, etc.; but when the atmosphere contains very little vapor,-as when it comes from an extensive region of dry land, or during the cold winter months in the interior of North America,—a much greater reduction of temperature is requisite to produce precipitation, because such air is not saturated. If two masses of atmospheric air of equal volumes, one at 60°, and the other at 80°, each saturated with transparent vapor, be

*Meteorological Essays.

mixed, condensation takes place, causing moisture, or precipitation; and the air at 60°, has its temperature elevated by the evolution of the latent caloric of vapor at 80 degrees.

When the wind has prevailed for some time from the ocean over the land, loaded with invisible vapor, it is condensed on meeting with a colder current from the upper or northern regions; and precipitation continues until the air from the ocean has deposited its vapor, or until it is driven back by the predominant force of a dry land wind.

4. It is susceptible of demonstration, that the amount of natural evaporation is every where in proportion to the amount of temperature. În the tropical regions, it is six or seven times greater than in the polar regions. At 93 Fahrenheit, the largest amount of aqueous vapor which can exist in the atmosphere is about one-twentieth of its volume; at 60° which is nearly the average temperature of Rome, Naples, and Charleston, S. C., it is one-fifty-eighth; while at 32°, which is above the average temperature of arctic America, it is about one hundred-and-fiftieth.

The transparency of the atmosphere is in proportion to its tempera. ture. This explains why there are more clear days in the tropical than in the middle or higher latitudes, and why the atmosphere is transparent below the region of the clouds, even when the sky is overcast; while the average quantity of vapor in the atmosphere decreases from below upwards, and from the equator to the poles.

To persons in the habit of observing the weather, it is well known that flashes of lightning, when occurring overhead, are immediately fol lowed by precipitations of rain. It is also known that lightning, thunder, and rain, are frequent in the tropical regions, and in the middle latitudes, during summer; while in the polar regions there is little or no lightning, nor in the middle latitudes during winter.

5. In the work on Terrestrial Magnetism, we endeavored to show the absurdity of admitting that vapor is raised into the atmosphere by caloric, and that it is condensed by the evolution of another distinct imponderable fluid, called electricity. If so, whence originates the electrity? Is it produced by the friction of currents of dry air, as supposed by Dr. Thomson?-or by the friction of salt and water in the ocean, as conjectured by Dr. Franklin?-or by chemical agency, and the growth of vegetation, as recently maintained by M. Pouillet? Unsatisfactory as these hypotheses may appear, they demonstrate the difficulty of accounting for its origin, when considered as a distinct elementary fluid from caloric. Dr. Franklin believed that vapor was held in a state of solu tion by electricity; but we have proved that caloric is the cause of all evaporation from which it follows irresistibly, that the latent caloric of vapor is the basis of atmospheric electricity.

The spaces between the atoms of water are forty times greater than are occupied by the impenetrable atoms, which spaces are filled with latent caloric-and the volume of water is increased one thousand eight hundred fold, when expanded by heat into vapor. This all pervading, fiery essence, is the parent of lightning, and of every other form of electricity. It is the active spirit of the storm and tempest'—the great vivifier or soul of Nature,

We are not authorized to predicate a primary distinction, until fully acquainted with all the different states and affections of caloric, under different circumstances; for example, in its combinations with different substances, in a solid, fluid, gaseous, or imponderable state-as with the matter of light-its diffusion, concentration, compression, etc. Moreover, we are not philosophically warranted in assigning more causes than are sufficient to explain the phenomena. Now the expansion of fluids by caloric explains satisfactorily the process of evaporation ;— and the passage of the same caloric out of the vapor is sufficient to account for its condensation : whether it pass out slowly and insensibly, or with rapid and explosive violence.

When caloric is given out gradually, condensation and precipitation result, without electrical phenomena-which explains the increased sultriness of the atmosphere during the formation of summer clouds, and the elevation of temperature which accompanies a fall of rain or snow when there is no northern wind. During winter, the difference of temperature between the masses of vapor is small in the middle latitudes, so that the equilibrium is restored gradually, and without explosion. During spring, and especially in April and May, when masses of warm and cold vapor frequently mingle, light showers are precipitated by the passage of caloric from one to the other; still without much lightning and thunder. But in the tropics, and the middle latitudes during summer, the atmosphere contains a large amount of invisible aqueous vapor, which is dissolved and expanded by heat. On approaching a mountain, or a mass of vapor charged minus, the igneous fluid is suddenly attracted from the plus to the minus body, causing terrific explosions of lightning and thunder, with torrents of rain.*

The opinion has hitherto prevailed, that lightning is accumulated in the clouds, that it darts from one cloud to another. Nothing could be more in opposition to the known laws of electricity than such a belief. How is it possible that electricity could accumulate so extensively in a conductor? Is it not universally known, that electricity cannot be accumulated in a moist atmosphere?—that it is attracted by moisture, and thus prevented from accumulating in the battery? It is accumulated in transparent aqueous vapor, and thence passes through the neighboring clouds, so as to present the appearance of originating in them, or of coming from them. There is caloric enough in a pound of vapor in a latent state, to raise ten pounds of water of the same temperature, 100 degrees, when set at liberty, by condensing the vapor. Atmospheric electricity is often attracted to the earth, by buildings, ships, mountains, trees, etc. and thus made to pass through such clouds as intervene; and hence the idea that it proceeds from the clouds as starting points; while it is an appearance, which a philosophical examination proves to be an illusion. For a further detail of facts connected with atmospheric electricity, the reader may consult the work on Magnetism.

* See New Theory of Terrestrial Magnetism, where the subject is treated more in detail. In that work, a large body of tropical or summer vapor is compared to an immense Leyden jar, charged with caloric or lightning.