The Secretary read as follows: Esoisssn DEPT. fasuisc'rox. February13, 1866. Sin: In relation to the resolutionsof the Legislature of Massachusettsin favor of an appropriation for the preservation of the harbor of Provincctown, Ac. referredtothis Dept. I haveto reportthat this harbor is of muchimportanceto the commerce of the country, and particular] to our coastingtrade. It bearsthe same relation to tonortheasterntrade that the Delawarebreakwaterdoesto the South and southwesterntrade. It 15ii harborofrefugc. in which numerousvesselsseekshelterand find security during adversewinds and galcs in the passagearound UnipeCod. ts importance is greater from beingfreefrom drift ice and thoroughly and locked. Asii natural harbor it possessesall that hasbeen obtainedat the costof nearly 2 million dollars in creatingsuch a refuge at the entranceof Delawarebay. such is its importance and value to the commerceof the country. Nature having provided it and the industry of our country having for yearspast greatly profited and benefitedby the soourity it affords, its preservation and)fOIBOlIOIhiavebeenand continueto be recom incn ed by this deptto the fosteringcare of the national authorities. Its preservationis mainlyfor commercialinterests. To this end structureson the ocean side of the narrow neck of sand beachare advisabletoprevent the oceanwavesbreakini acrossthat neck and driving the sands into partsof the harbor now resortedto and valuable for thesniallcrclass of coasting vessels aswell asguardingagainstmoreenlargedencroach mentsfrom the command contraction of this valued natural roadstead. The snperintendingengineerhas presentedan estimate for severaloperationsthat hcconsidersexpe gigwbrd proper to be constructed.amounting to There may be well foundedobjectionsto a part of the systemthus recommended. Until the subjectis morefully studiedand examinedin all its bearings by some competentboard that shall be ordered to examineit. the deptean only recommendan appropriation for protectin i hcencroachmentsof the sen.upon the narrow iicc indicatedon the plan by the letters A by C; and for this purpose the sum ofSSJJ‘Jt)should sufficeto do all that at this time is advisable.profitingbythe experiencegainedforsimilar protectionon the Atlantic sideof Sandy Hook, NewYork. As a military silo it is of importance as a harbor for our vesscls of wnr underall the varied circumstancesofoffcnseand defenseof and from our coast by a floating force. If in possession of anenemy.the harbor of Boston is scale by blockade as long asa superiorfloatingforcecanoccupyit. Whatever may be our naval forceat times. it may be inferior to a single as well as a combined naval European an tagonist. To preserveits useandvalue for purposes of peace and war. its anchorage should he commanded by permanent defenseson the land, mounting the heaviest of artillery and a number of the longest ransremortars. When such artillery is mounted in works susceptibleof defenseon the land asw el als from the water, it is believedthat all the conditions arefulfilled that the nature of the casedemands. It is not consideredthat a.railroad fromOrleansto Proviiicctown should be constructedby the U.S.asa necessaryelementof efficiencyIn the do fcnseof this harbor. Wheneveran enemyshall set foot on shoreto make an attack by land upon any defensivework at Provincetown.t e population i n his rear in the districts betweenBoston and Pron dencewould render such an enterprise next to impracticable. Respectfully.your obedientservan RICHARD DEL FIELD. BreastHI 'or General, Chief Engineer U.S. Army. Hon. E. M. Sn mos, SecyWar.