From The Southwest

Cairo, July 31. Rebel prisoners ay that had Colonel Brooks' expedition been sent out from Heleua a few day since, Gen. Robbins would havo attaoked tbe plantations below that place the next day, and drawo all the lorce he coald out of Helena, while Shelby, with some 4,000 men, was to attaok the place from the northwest, and overpower the stnall forcé left in the fortifications. The Conatitutional Convention of Louisiana, July 22d, adopted a new Constitutioo by a large tnajority, and would immediately eubmit it to the peopie. Gen. Banks has prohibited the transfer of gold to the rebel States, and scopped all trafile in gold, except purchases deposited in the United States Treasury, and deposits to bo drawn only on satisfactory explanations of the purpose to which they are to be applied. The steamer Henry Ames, from St. Louis, struck JV snag yesterday, seven miles above here, and sunk over her maii) deck. Sbe will probably be a total loss. Her deck freight, which was very valunble, was taken off slightly damaged and brought herc. Sixty bogsheads of tobáceo, one thousand barrels of flour, and a large lot pf nails and :private freights, besides a large amount of pork belonging to the goveronient is still jn the hold. The steamer Graham frora Memphis, July 29th, brings tho body of Major Lawson, of the 77th Ohio, who died of wounds received at Tupello. The Bulletin contaios further particular of the late fight held near Helena. Our total loss was sixty-two, inolud'ing four offioers killed. Kebel loss 250. The Bulletins account of the destritction of the steamer Clara Bell says that four companies of the 6th Michigan Infantry were aboard at the time of tbe attack, and fouod the boat siukiog aud the crew about to surrender, whea tho offioers of the regiment ordered the boat run to the Mississippi shore. The oidier tben fired ber to prevent her falling into tho hinde of the rebele,