Gentlemen: General Ulysses S. Grant, the late President of the United States, sailed from Philadelphia on the 17th inst, for Liverpool. The route and extent of his travels, as well as the duration Of' his sojourn abroad, were alike undetermined at the time of his departure, the object of his journey being to secure a few months of rest and recreation after sixteen years of unremitting and devoted labor in the military and civil service of his country.