Gen. Taylor has written a letter respecting the operations in Mexico, which, although addressed to a friend, has found its way into the papers,and is extensively published by them. The following is an extract : " I do not intend to carry on my operations (as previouÃly stated) beyond Saltillo, deeming it next to impracticable to do so. It then becomes a question ns to what is best to bo done. It seems Jo me that the mosl judicious course lo be pursuod on our part would be to lake possession at once of the line we would accept by ncgotiation, extending frcm the Gulf of Mexico to the Pacific,and occupy the same, or keep what we already have possession of; and thai, with Tampico, (which I hope to take in. the course of the next month, or assoon as I can get the means of transportation,) will give us all on this side of the Sierra Madre, and, ns soon as I occupy Saltillo, will include six or seven States or Provinces,thus holding Tampico, Vicloria, Monte rey, Saltillo, Monclovin, Chihuahua, ('which I presume General Wool has possession of by this timej Santa Fe and the Californias, and say to Mexico, "Drive us from the country" - throwing on her the responsibility and expense of carrying on-oflensive war; at the same time closely blockading 11 her ports on the Pacific and the Gulf. A course of this kind, if persevered in for a short time, would soon bring her to her proper senses, and compel her to sue for peace, provided there is a Government in the country suiÃ¯Ã¯ciently sfable for us to treatwith, which I fear will hardly be the case for many years to come. Without large reinforcements of volunteers from the United States- sny ten or fifteen thousand, (those previously sent out having already beon greatly reduced by sickness and other casual itiesj - Ido not believe it would be advisable to march beyond Saltillo, which is more than two hundred miles beyond our depots on the Rio Grande - a very long line on which to keep supplies ('over a land route, in a country like thisj for a large force, and certain to be afrended with an expense which will be frightful to contÃ©mplate when closely looked into. From Saltillo to San Luis PotosÃ, the noxt place of importance on the road to the city of Mexico,is three hundred miles; one hundred and forty badly watered, where no supplies of any kind could be procured for men or horses. I have informed the War Department that 20,000 efficiÃ«nt men would be necessary to ensure success if we move on that place, (a city containing a population of 60,000,where the enemy could bring togcther andsustain, besides the citizens, anarmy of50,000,) a force which, I apprehend, will hardly be colleeted by us with the trnin necessary to fced it,ns well as to transport v.irious other supplies, pnrticularly ordnance and munitions of war." The following remarks from the N. Y. Evening Post seems to show that after all thecry about Federalism, the war rnay not be very popular in at least some portions of ;hc Democratie party. "Wcbegan the war [mark this admission: wc hrgan the wnr] against the Mexican ruers, in markcd contradistinction to the people; it hÃ¶s nlready become a war with ihepeoplc- a war with that invincible Dower, theprincpla of nationaVdy. The women are noic, by hundreds, aiding to huild fortijications, and boys offourtcen are voluntccring. We may bea them in i hundred battles and e.xtremity will only serva to crente renewed resources: while on such a plnn, penetrating further and urther into the interior, with nece-sarily ncreasing forces, the time can not be Par distant when Mr. Webster's say ing of he half-million n day will acquire a truth 00 ndeninble and too fatal. With such 1 war, inglorious enougk even m its most tplendid successes, contrast such a plan as hat tbove stated, and the plain common ense of every reader cannot, as it seems o me, hesitate in the choice between the wo."