The heaviest pieces placed in position in the trenches before Sebastopol were, by the English, the 68-pounder gun of 10,640 pounds,and the 13-inch sea-service mortar of 11,300 pounds,and, by the French, the canon de 50 of 10,190 pounds, and the mortier de 32c of 9,615 pounds. The 200-pounder Parrott weighs 16,570 pounds, and the 13-inch sea-service mortar (1861) 17,120 pounds. The guns placed in position before Yorktown exceed, therefore, in weight by 50 per cent. any guns that have ever before been placed in siege batteries. I have, therefore, been thus particular in detailing the manner in which they have been placed in position. I do not believe that any very great difficulty would be found in moving the 200-pounder by the sling-cart over very good roads, but the dimensions of the 13-inch sea-service mortars (43 inches carriage, as the mortar when slung on the sling-cart hangs 20 inches below the tires of the wheels. In the battery, ways of logs, with flanks spiked on top, were constructed, and the ground excavated between to permit the passage of the mortar, but this could only be done upon hard ground.

In the arranging of the stores and maneuvering of the guns the following points in which improvements might be made suggested themselves,and are respectfully submitted for consideration:

1. That the construction of the pole of the hand sling-cart be altered as above mentioned.

2. That the simplicity of the siege platform be still further increased by making no distinction between mortars, sleepers, and front and rear pieces and deck plank-i.e. by boring dowel-holes in all the pieces, sending the dowels in bundles, to be placed in where necessary,and leaving the bolt-holes to be bored in the battery.

3. That a certain supply of tools, most of them now found in battery wagon D, be supplied with the gun and mortar implements at the rate of one for each five pieces, viz; 2-foot rule, an auger, a mortar level, (the gunners' level not being convenient for laying platforms), a handsaw, a cold-chisel, and a battery lantern; that a magazine be allowed for every five guns, and a complete set of magazine implements (Ordnance Manual, p. 367). including copper adzes and dark-lanterns, be supplied for each magazine. Battery wagon D is admirably suited for depot purposes, but if each battery and battery magazine is supplied with them the battery wagons are soon exhausted of these stores, without the other stores which they contain being called for at all.

4. That a full complement of the machines and ropes specified in Ordnance Manual, page 367, be sent with each train, and that in addition 3-inch planking, skidding, blocking, spare tackle-blocks, and a number of small tackles, consisting of wooden double and single blocks, with 2 3/4-inch falls, be provided.

5. In maneuvering the 13-inch mortars it became evident that the iron-shod handspike provided were not sufficiently strong.

6. The steps of the wrought-iron mortar-carriage require an upright brace, or the upper one becomes crooked in mounting the mortar.

Only one battery (Numbers 1.) of five 100-pounders and one 200-pounder Parrott opened fire during the siege. This battery opened fire on the 1st of May, and at once drove all the rebel shipping from the wharves at Yorktown. In all, 137 rounds from the 100-pounders and 4 rounds from the 200-pounder were fired. An inspector of the batteries on the river front of the Yorktown fortifications will afford the best indication of the very accurate practice made from this battery; but the impossibility of observing with equal accuracy the results of