6 feet high in the clear, with a filling room 4 feet by 5 feet by 6 feet high; the latter was 10 feet by 15 feet by 6 feet high, with one return gallery 4 feet by 6 feet high. The magazine frames were of 4-inch by 6-inch stuff, placed 2 feet 6 inches apart, and covered with 3-inch plank and 8 feet of sand on the line of least resistance, and for sheeting 1-inch, 1 1/4-inch or 2-inch plank was used as could be procured.

Temporary platforms for the four 100-pounder guns were constructed by Sergeant Clark, New York Volunteer Engineers, which answered all requirements, and were uninjured at the close of the siege.

The 300-pounder battery.- Having no experience to guide me in the construction of a battery for a gun of such a caliber, and knowing its value in the eyes of all, it is not surprising that every precaution was taken to guard it from every possible accident. Being also unaware of the effects of its discharge in reference to its disturbing influence on the ground in its immediate vicinity, and fearful that, with such a mobile and shifting material as sand, the ordinary revetments would not withstand its discharge, great precautions were taken to counteract every supposable effect. The dimensions of the battery were as follows:

Feet.

Height of crest of parapet above tide mark.............. 20

Height of crest of parapet above platform of gun........ 12

Height of barbette above platform....................... 5

Thickness of parapet at top............................. 18

Thickness of barbette at top............................ 25

Radious of epaulement at base........................... 12

Interior slope, 3 upon 1.

Distance of center pintle from foot of interior slope, 7 feet 3 inches.

The interior revetment was first of sand-bags 2 feet thick, against which one of marsh sods 1 foot thick was built, which latter it was found made a good strong binding and durable revetment. The top of the battery was covered also with these sods, which, besides keeping the sand from blowing, also prevented the rain from washing it down. The single cheek of the embrasure was rivetted with gabions, and the sole or barbette was laid with fascines, everything else tried being unable to withstand the powerful blast of the piece. For facility in loading, steps were arranged to lead to a box or trough in front of the muzzle, and sunk in the parapet, which permitted 4 men to stand while lifting the shell into the piece. In constructing the parapet, the sand was thrown from the ditch to the parapet by relays, forming terraces, which were afterward left in that condition.

The magazine for this gun was ample for its service, being 10 feet by 15 feet by 6 feet high, and constructed like the others. A bomb-proof for the signal and telegraph operators, 11 feet square, was built near this magazine shortly afterward.

I must state that great credit is due Lieutenant McGuire, New York Volunteer Engineers, for his constant and unwearied attention to the work, and of whose long service and many practical and useful ideas I very often availed myself. I must mention also Sergeants [Lionel] Anyan and [Samuel] Clark, Company A, of the same regiment (the latter afterward killed at Battery Gregg), for unusual energy and intelligence int he discharge of their duties.

From this time until the 31st of August, I was engaged in simply overlooking the condition of these batteries, and seeing to the repairs and alterations required.