QUICK SAILING.-The Pittsburg Gazette says that the J. M. White, Capt. Jos. M. Couvers master, has made a trip from New Orleans to St. Louis, 1180 miles, against a tremendous current, in 3 days, 23 hours and 9 minutes! This is at the rate of 4 minutes 50 seconds, and 17-60 of a second to the mile-about 12 and 1-3 miles an hour, including all stoppages! This is the quickest trip ever made, and the J. M. White is a Pittsburg boat. But this passage is no test of her actual speed against time; to ascertain that, we must take some run she has made without stopping her wheel. She has made the run from New Orleans to Donaldsonville, 82 measured miles, in 4 hours and 35 minutes, being at the rate of a mile in 3 minutes, 21 seconds and 13-60ths of a second, or 18 miles an hour against the current of the Mississippi!! Pittsburg against the world.