UNITED STATES,Mcwfrfa** at War.--Notc* or Frxpakatio!*. i — I he preparations of Government for prosecuting the present war with Mencn, indicate vigorous if noi protracted hostilities# Kroan appearances in this | city alone, person would be led to suppose Chat the j force to be brought into the field, either at once or successively, would , not be much less than half a tf lilt ion of men, and elperime/nt have lieen tried and arrangements made which show conclusively, that either the government are led to expect a more obstinate contest on the part of Mexico than what was anticipated, or that* by the gigantic character of our preparations, the overwhelming force to le employed, and the vigour of our blows when ready to act, it intends to crush that power at once, and render resistance 10 us out of the question. A con-[ tract ha* just been completed bv Mr# Thos# 9.Barnstead, of Southwark, for supplying the govern-j ment with from fifty to eighty thousand sets of tent ipoles.The United States army regulations prescribes eight men to a tent* and at thia rate provision lias been made in one contract alone for lodging on the field a force of about 400,000 men. But it is not unreasonable to suppose that there are others In the country engaged in the same work# Exclusive of thift supposition, Mr. tiarnttead has had a number ot contracts of a similar character since Inst fall, and it is estimated that provision has been made in this way fbr about a million and a half of troops. The tents for which the above poles are made have been for a long time* and are now in process of manufacture in all the principal aail lofts of the city and county of Philadelphia, and perhaps of the other cities of the Union, We hove already noticed the construction of wagonafor the army, and understand that a similar state of activity prevails throughout all branches of the war department.—PKHadtlpkim Ledger.