More About Those Immense Mortars

I no ti iin:p;il puit ol llio lichting, and withirkit douw tb ■ p t i n .! j :. 1 iiyirv, !i'i-n done ly Mier monster inortart. ThoHu enurnioiid piecéa ol' o rd nance weie regardod n soiae sense ;is an experiment it the time of their oonstruo' . lian, their runge, wucurKoy, and c'urabiliiy biing questioos Air from settíed. Their orkipg. hiif aktney pul Ihfir i:!i':it 11:01 it in tliis surt ol arfare buy- -nú or.tiove:s.y. Tl'cv nr'o fha largest gi;ns of the ! kiiul itow ín Itie AflieriCnn eetvice, and !i;if (:mih begining wotkcd adinimhly. 'I lio örst liifficnliy, oí ourne, waa wiih llicm, (18 wi'.li most tire anns, a ivi nt ol (íimHiaritjr wkh their use, A cernin ::.:i'.Mi!ci-ii) Irwd to be run chrongh in order to vvield the.m with anv degroo ol efficiency. Nearly uli of ihu liring 0} the psist í'ow dsvsi l:i.s, í hiko i , been of t!i s éxpetimentnl charncter. The gwntMírs netídyd to lio trained in tlitíir service, ifnd here I might sny that it iViiüi boing otR-ious or dangerírtw hut, nu the coüirary, by far llo íiiiist 6üfè nuil pleitsant of iho heavy nidoHnbu tervite. A dozen or two rniiipl.-, it vai'uMis antrlcs. and riotis charles of powdvr, is found to ' be uffiicicnt for ordinary piirposcs. The iingJe foand to be inbsl effect ivo for lontr distnnces s, I beliove, fortyfive degreés, which, wilh a clu-rcre ol twclve ;.mi a h.ilf pounds of powder, will send ilio mammoth f',ioll two ;.nd a hall' to three miles. Charges as high is thirtv pounds have beéy lircd at a lowur cUvation, without, hmvever, mateiially ncreasing the distaneo. It is satisfaotary to knowj inpTeover, that these mort ara, large as thoy are, can not óobtain powder enough to burst tlem. This is consolatory, inasmuch as wo have lost severa] mon by tho bursting ofrifltíd gafla on three scvural occasions, oii board tho gunboats. Their efficiency his been tosted in numerons ways sinco our arrival here. With good glassea thy can boscen to fall uto tho rebel battoriea and to burst wi;h a trenienáóua explosión, scfttteriDg dea th and destruction wide arounil them. Some trouble is experúsneod with the fuses, the first of wiiii-h (veré too oíd to be certain of operatioo. New ones have been procnied, and hall' of them burdt too soon esptoding high in the air or plunging deep inlo the waters, ethers being lost sight ol so that no account can ever be tale en of them. The charge ol these shtfHe, reenguring, as they do, over three feet in circumference, is seven poiituls of powder, and the report which they giv.e forth even at tho distance of threo miles, is louder thun that of ordinary 64 pounde's. Two ot thuso niortars are now on tho Missouri shore and four others ncar the point. They are worked in gangf who are on duty ix hours in the twenty-four, and uniese specially engaged, íire once in half an hour. The gtmners are taken to the boats by little tugs, and returnod to their quarter a raile up the river, after their '' watch" has expired. 'i he explosión of these huge engines I have spoken of before as best described bv tho adjective terrific. To one at a distance from them, ospecially in the line of firo, tho report is soraething appalling, and ve nre cofidemly told they can be distinctly heard at a dJstanue f til'y miles. When standing near the mortíir, however, tho noiso i.s not so loud, but the concusión is sneh as to shatter every nerve in one's body. and actually started the soldering of the stcain-pipes of one Rteamcr whöB lvingalong side doring the firing. Some interesting fncts are told concerr.ing the [tremondous draught created by the vacuüm of the discharged mortar. Pieces ol clothing have been bronght from a distance into tho boat', and yesterday morning tlie metal button from tho jacket of one of the gotiners, lying a few fcot in front of the portar, was broken clean from its tém and sucked into tiie mortar, wherc it was fonr.d imróednately aiterward. Severa] men b'ave been knocked down bv the wind, thongh standing fifty yards away from the piece when it was firecl. 'i ho raortars Lavo made a completa circuit artmnd tho point. and have had the eifect of maKing it tOÍeFI))y risky or anV rebel craft tf appeftr within two miles of the point nt which thoy hiy wathoraA. Oafttsin Wheelock -as incKv' cnough to put thrce Bucceesive shols into tiie higiior battery, one of wbiuh atriick down tho flasr.