one hundred and five channel-bearing guns being en barbette. The exterior battery (twenty-five guns) has its crest (same as Saip Philip) 14 feet above low water of rive. The covert-way batteries (forty-eight guns) have their crest 16 feet above low water, and the crest of parapets of main work (twenty-eight channel-bearing guns) is 24 feet above low water.
The two works mount together one hundred and seventy-seven channel-bearing guns.
Of this armament there was in Fort Jackson (as before stated) when it went into rebel possession sixteen 32-pounders (without carriages), twenty-six 24-pounders, with fourteen casemate and twelve barbette carriages; and at Saint Philip ten 24-pounder with carriages, or fifty-two guns in all of not very formidable caliber.
Whether they have supplies the full armament or not I cannot judge. There were in the Baton Rouge Arsenal forty 32-pounders and three 8-inch columbiads, which, if all sent to these works, would leave eighty-two still to be supplied.
Except Baton Rouge, the Norfolk navy-yard, and their own foundries have been their sources, and as it is likely their foundries have been mainly taken up with casting field guns, it is probable that Norfolk has been the source from which forts have been supplied.
It is probable, therefore, that, as at Port Royal and Hatteras, the armament, if completed, will contain few guns over 32-pounders.
Such an armament, as much experience has shown, is not very formidable of hot shot (and there are furnaces for nearly all the batteries at both forts). Still, it is not a striking undertaking to pass so large a number of guns at such close quarters. (Fort Saint Philip is about 700 yards higher up the river than Fort Jackson; the distance between the nearest salients of the main works is about 1,000 yards.) From to another 1 1/2 miles above the nearest upward-bearing batteries we shall and find a distance of 3 1/2 miles to be traversed, 2 miles of which under the fire of from 100 to 125 guns, and the other 1 1/2 miles under that of from 50 to 100. Now, against the current of the river this distance will not be performed by the majority of steamers of a squadron in less than twenty-five minutes or a half hour. With hot shot thrown by this armament, even though but 24 and 32 pounders, I should look upon the daylight passage as too hazardous to be undertaken. The lowness of their barbette batteries is a favorable circumstance. At any time between now and next August our fleet would find the river pretty well up. The river is not apt to be much above low water in February, but a rapid rise usually commences about the 1st March and the river keeps up till August, and the decks of our large frigates would command most of these batteries, within 200 or 250 yards of which they could be laid. But to get such positions the vessels would have to endure 1 1/2 or 2 miles fire (raking) of 100 guns.
Such an attempt should be made at night, when the distance fire must be very uncertain.
From two to four or move vessels for each fort, armed with 9 or 11 inch guns, laid alongside of Fort Jackson, and firing spherical case or canister (the latter probably preferable), would, I should think, make all these batteries untenable, even those of the casemats. Here is a place where armor-clad vessels become particularly applicable.
Should any obstructions (such as rafts) be anchored in the river (difficult, I think, to maintain in the high, or even moderately high, stages)