The fuTlowing letter froin ex-President Pierce to tho late Senator Pearoe, of Maryltwd, in regard to arbitra-y arrests, has never btforo buen publihed : Concord, N. H., Jan. 15, 1862. My De. ui Sir- I rend with unusual interest and satisfaotion the debate whicb occurred in the Senate, on the lGth uit , upon the resolutionti of Mr. Trumbull, nid desire to expresa my thanks for the sentimonta and thoughts whioh tho oc.OflgiÓB e'icited froin yon. - My conviuticra iind oympatfaioa ara with you tHoroug-hly whon vou av, "I do not believe that it (inprinonment upon htlrot de cachet) promoles the pur posea of those who desiro to Heo Üiis Union brought t"gether. again - an lj et of all otiléis, to me the most desiiable, if it bo possible." In my e-timation, tho mover of the inquiry deserves the gratitude of freetnen everywhere, and only utters Iruth with force when he decíales hat "the power without charge, without examination, wiiho'it opportunity of replv, at the cick of ihe lelegruph to arrest a man in a peaceable portion of the country and imprson him,' is " of the essence of despntism." And yet tho public mind (hun far would neem to have been scareely more roused bv current even 1 8 of t u character than it uiis yeara ago, when we raceived accoiwitu of similar inc.iicerations, ordeied bv the fat her of the novv deposed King of the Tifo Sicilies. Hov ineredible it will appear hereafler, when hi-tory whali be wiïtten up, tliat at this peiiotl df the liepublic the cons'itutioual safegnards of personal liberty cnuld have beeu so easily and ith so littlo npparunt coneetü sept awuy. The Seeretarv of State, on the 20th ult.,füur days after the debate in hich you participated, addrtssed :n ofjitial note to me, whiuh aeeras to Ilústrate in a istriking mi nuer the i-light groundí", ni' rather the groundless sut-picions, upon wbieh in these times ci'.izens ara liable to sufier in reputatio;), if not in loss of liberty. I replied without delay, and, so lar us I am per.-onally affeeted, may, L trust, well leave tho matter in quietness upon the files of the departuient. It is my belief, however, that no recent rneasure has been fraught with more nwchief tlian the irsuing of leiiren de rarhet, and conserjuent arresta and impri.onments, in riolation of the provisions of the constituí ion ; and the ear'ier ihe sytem is effio!ual!y ;heeked tbe better it will be for the governrnent and the country, as well aa for the nbjects of oppresion The evidence ia abundant to show that the plea of necenity: exept in the presenceof imtneditto neighborh'od of hostüe arn'ies, w here the adtnini-uration of law under tho usual torm inay be ineritably suspended, is not graciously Bi:cepted IV the tnass of the people. Uaiun without securi'y for personal liberty is not ihe Union which they have cherished and to the restomtion of which thay look with earnest desire and hope. Nothing, perhaps, could express more cloaily their views on this point than the lanir"íe of the great modern historian, who died at a comparatively recent period, leaving his work incomplete. In traoing tho successive steps in the progre-8 of Britife liberty, Mr. MaoHulay wiyu: "We have been taugh', by lmg ex[eiience. that we cannot, without danser, suffer any breach of the constitution to pnss unootioéd." '' As we cannot, without the risk of evils from whii-h imaination recoiU, employ phvsical iiu'ce aa check on ini-gnveniinent, it is evidently our wisdom lo keep ill constitntional check-i on nii.-Llvernmenl in the highest state of efficiency - to watch with jealini y the tirst beginiiii.irs rf encmachmen', nri never to sufFor irregu'arities, even when harinlesr in themselves, to pas-s unchallenged, lest they aoqnire the [oree of precedent." Who in our land will alfiiin tiiat üiy otlier doctrine oithy df tho-e who hold iheirright i;ri'K-r a solernti, written charter ? It is chöoring to know ha', inquiry has Wen moved in the right q larter, and tht able Htid tearle-s men are s'irred bv a ense of hal is due to our fellow citizjns, who havi'jbeen 'mprisoned without asiu'ii'.ient of cause and di-charged without explanation ; and, yet. more, Mich as ares:ill n conflnenrant and preeluded by guards and prison liolta l.din the privilege of the " grat writ ■f liberty," a-id thua of confrontino;, before a competent ju licial tribuna!, sugestión of crime, which the act of nip ■iiintnent itaelf itnplies. Of this latter cl is-j, I be ieve, Iroin my knowledge of ihe men, are not a few wolthy sous of Muryland, who love tho Union, as you d:, and who have stnven not to destroy but to preserve it. If Iro fr.)in any luint of crime, as I take them lo Imi, thuv will derive iinf.iiling otipaoity for endurano from the eonsciousness that tliry have nounshed iheir m.inly strungl+i to s'.rike s'out blows at tlie foundation which their fa'hers luid - - thut tht'V have never paricipated in lines of aotion or in startling ut terances, ui tiTances calculated to en courage aggressioq upon the rights and innlitutiotij of sovereiiin 8tates- to fister seutional distrust auq aninosity, or to in mgurate conflict belween different paris of the c.oi.fifderation, and thus to waaken unity of feuling, interest, and purpose. If, n the other hand, they are gililty, the la-v wiil nflict adequate punishinent, whatever th.it m iy be, as it shnulij do. Uut liow long in such a duránuii without a hearing tj be their allotment ? I ara, v.'iy truly, your frieatl, FEANKLIH PIERCE. Hou. James A. Pearco; Uuüe;l Stales Senator, Washington, D. O.