Close upon the rear guard of the Queen's forces followed the light troops of Aurelian, and early this morning it was proclaimed that the armies of Rome were in sight, and fast approaching the city. These armies were considered too numerous to hazard another battle, therefore the gates were shut, and we are now beleaguered by a power too mighty to contend with, and which the Arabs, the climate, and want, must be trusted to subdue. The circumjacent plains are filled with the legions of Rome. Exhausted, by the march across the desert, they have but pitched their tents, and now repose.

The Queen displays more than ever her accustomed activity and energy. She examines in person every part of the vast extent of wall, and every engine planted upon them for their defence. By her frequent presence in every part of the city she inspires her soldiers with the same spirit which possesses herself; and for herself, to behold her careering through the streets of the city, reviewing, and often addressing, the different divisions of the army, and issuing her commands, she seems rather like one who is now Queen of the East, and is soon to be of the world, than one whose dominion is already narrowed down to the compass of a single city, and may shortly be deprived even of that. The lofty dignity of her air has assumed a more imposing greatness still. The imperial magnificence of her state is noways diminished, but rather increased, so that by a sort of delusion of the senses, she seems more a Queen than ever. By her native vigor and goodness, and by the addition of a most consummate art, by which she manages as she will a people whom she perfectly comprehends, she is at this moment more deeply intrenched within the affections of her subjects, and more completely the object of their idolatrous homage than ever before. Yet in her secret soul there is a deep depression, and a loss of confidence in her cause, which amounts not yet to a loss of hope, but approaches it. This is seen by those who can observe her in her more quiet hours, when the glare of public action and station is off, and her mind is left to its own workings. But, like those who play at dice, she has staked all--her kingdom, her crown--her life perhaps--upon a single throw, and having wound herself up to the desperate act, all the entreaty or argument of the whole earth could not move her to unclasp the hand that wields the fatal box. She will abide the throw.

There are still those who use both intreaty and argument to persuade her even at this late hour to make the best terms she may with Rome. Otho, though perfectly loyal and true, ceases not to press upon her, both in public and in private, those considerations which may have any weight with her to induce a change of measures. But it has thus far been to no purpose. Others there are who, as the danger increases, become more and more restless, and scruple not to let their voice be heard in loud complaint and discontent, but they are too few in proportion to the whole, to make them objects of apprehension. It will however be strange if, as the siege is prolonged, they do not receive such accessions of strength as to render them dangerous.

The Emperor has commenced his attacks upon the city in a manner that shows him unacquainted with its strength. The battle has raged fiercely all day, with great loss we infer to the Romans, with none we know to the Palmyrenes.

Early on the morning of the second day it was evident that a general assault was to be made. The Roman army completely surrounded the city, at the same signal approached, and under cover of their shields, attempted both to undermine and scale the walls. But their attempts were met with such vigor, and with such advantage of action by the besieged, that although repeated many times during the day, they have resulted in only loss and death to the assailants. It is incredible the variety and ingenuity of the contrivances by which the Queen's forces beat off and rendered ineffectual all the successive movements of the enemy, in their attempts to surmount the walls. Not only from every part of them were showers of arrows discharged from the bows of experienced archers, but from engines also, by which they were driven to a much greater distance, and with great increase of force.

This soon rendered every attack of this nature useless and worse, and their efforts were then concentrated upon the several gates, which simultaneously were attempted to be broken in, fired, or undermined. But here again, as often as these attempts were renewed, were they defeated, and great destruction made of those engaged in them. The troops approached as is usual, covered completely, or buried rather, beneath their shields. They were suffered to form directly under the walls, and actually commence their work of destruction, when suddenly from the towers of the gates, and through channels constructed for the purpose in every part of the masonry, torrents of liquid fire were poured upon the iron roof, beneath which the soldiers worked. This at first they endured. The melted substances ran off from the polished surface of the shields, and the stones which were dashed upon them from engines, after rattling and bounding over their heads, rolled harmless to the ground. But there was in reserve a foe which they could not encounter. When it was found that the fiery streams flowed down the slanting sides of the shell, penetrating scarcely at all through the crevices of the well-joined shields, it was suggested by the ingenious Periander, that there should first be thrown down a quantity of pitch in a half melted state, by which the whole surface of the roof should be completely covered, and which should then, by a fresh discharge of fire, be set in a blaze, the effect of which must be to heat the shields to such a degree, that they could neither be held, nor the heat beneath endured by the miners. This was immediately resorted to at all the gates, and the success was complete. For no sooner was the cold pitch set on fire and constantly fed by fresh quantities from above, than the heat became insupportable to those below, who suddenly letting go their hold, and breaking away from their compacted form, in hope to escape from the stifling heat, the burning substance then poured in upon them, and vast numbers perished miserably upon the spot, or ran burning, and howling with pain, toward the camp. The slaughter made was very great, and terrible to behold.

Nevertheless, the next day the same attempts were renewed, in the hope, we supposed, that the Queen's missiles might be expended, but were defeated again in the same manner and with like success.

These things being so, and Aurelian being apparently convinced that the city cannot be taken by storm, the enemy are now employed in surrounding it with a double ditch and rampart, as defences both against us and our allies, between which the army is to be safely encamped; an immense labor, to which I believe a Roman army is alone equal. While this has been doing, the Palmyrenes have made frequent sallies from the gates, greatly interrupting the progress of the work, and inflicting severe losses. These attacks have usually been made at night, when the soldiers have been wearied by the exhausting toil of the day, and only a small proportion of the whole have been in a condition to ward off the blows.

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The Roman works are at length completed. Every lofty palm tree, every cedar, every terebinth, has disappeared from the surrounding plains, to be converted into battering rams, or wrought into immense towers, fire and constantly fed by fresh quantities from above, than the heat became insupportable to those below, who suddenly letting go their hold, and breaking away from their compacted form, in hope to escape from the stifling heat, the burning substance then poured in upon them, and vast numbers perished miserably upon the spot, or ran burning, and howling with pain, toward the camp. The slaughter made was very great, and terrible to behold.