l'rom Apploton'H Journul. Rapid as Í8 the growth of this country in wcalth and population, its postal growth is yct moro wov.derful. In 1 ((), with a populiition of 31,500,000, "Ü0,000,000 of letters passed through tho mails ; eight letter per annum for overy man, woman, and child in the country. In l!S0, the population had grown to 30,000,000. wliile the number of letters had increased to 610,000,000, or 1G Lettore per eapita ]:amium; un increase of 100 per cent. in letters, to 25 per cent. in population. In otlmr wordp, letters increased four timos asfast as population. Part of this ino,ro:isc may bo duo to bettcr oduc&tion, but the most of it to the. expansión of business. Tho proportion of letters to population is far greater iu citios than in tho country. In Washington's l'residency, 4,000,000 of people sent 00,000 letters a year, only one letter for overy 13 parsons each year. : During tho pust fiscal yoar, the nation has paid lftj60ö,OOO for the transportation of the mails ; 20 years ago it paid Iets than f5,000,000. 'This would indícate ttiivt the postal expenses doublé tlieinselves overy ten years. E tob yiir puts 900 new post offices in Operation, and carries tho mail about 7,K0 more railes. In 1 SI 7, Mr. JosepK Dödd wasappointed to carry the "Great Southern mail" from tho New York post oöico across tho teny, Wbeeling it to the water's edge in his wheel-barrow, ho transported it across tho ferry in his open boat to the waiting stage. During tho present year, nearly eight tons of imiil-iiiaf.ter daily leavo tho oirice of this city for tho South by thu Cauidon and Amboy llailroad alorte. Should tho postal growth of tho next half century equul the per of tho last, its close will st.'e largo trains of oars laden with muil-matter alone. No passenger will be allowed to enter tho train nhiiiily overciowded with, letters and papore.