AMERICAN FRANCS-TIREURS.--PONTOON BRIDGE OVER THE LOIRE.--FRENCH CARELESSNESS.--SOLITARY DEATHS OF THE WOUNDED. About this time a small regiment of American volunteers, in Franc-Tireur uniform, passed through Orleans on their way to the front. Their Colonel called on us, and offered a place as assistant surgeon to any who might be willing to join. Had I been at liberty, the spirit of adventure would assuredly have prompted me to accept his offer, and he pressed me hard to do so; but the required permission was wanting. These men, I afterwards heard, joined General Bourbaki, and having been driven over the Swiss frontier, were detained as prisoners of war. About the 20th November Dr. Pratt returned, bringing with him two gentlemen, Mr. Olive and Mr. Wombwell, who were to take charge of the commissariat and store department. They had been in London, and brought a large supply of stores. They, like Hayden and myself, had been taken by Francs-Tireurs, not once, however, but twice, and only the French passport which Dr. Pratt held ever since his departure from Paris, prevented them from being shot out of hand as Prussian spies. A work of great interest was being carried on by the garrison within sight of our windows on the Quai. It was the construction of a pontoon bridge across the Loire, for the more speedy passage of troops. The Germans, some weeks previously, at the time we arrived in Orleans, had attempted a similar bridge; but before they had half finished it, a flood came one night and swept the whole thing away, to the intense amusement and delight of the Orleaners. The pontoon bridge which the French now constructed, showed not only the perfection to which military engineering had been brought, but also the acquaintance which the natives possessed with the sudden and violent floods which were wont unexpectedly to swell the current of that great river, causing its waters to rise in a few hours so as to overflow its banks and flood the adjoining country. The bridge was composed, not of pontoon boats, but of large barges, which had been used on the river for the freight of merchandise. These were connected with one another by pine trees, which themselves had been lashed together by spars. A rough idea of the size of the bridge will be given if I state that it took thirty-three such barges to make its length, and that they were about ten feet apart. Active preparations were now being made on all sides for a determined stand. Every one said that ere many days were over, the enemy would be once more upon them, but they reckoned that an engagement, though sure to be bloody and desperate, would end in a decisive victory for the French army. Such was the gossip of the town, and of officers in the cafés whom I fell in with.