By the last Letters from America we are informed, that the Provincials are very successful in their naval Enterprizes, and that the British Flag in those Parts has already received every Sort of Insult; some of our Vessels being almost daily taken under the Eyes of the Fleet: On the other hand, the Provincial Army seems by its Inactivity to be already benumbed by the Season; not one British Post near Boston had been disturbed within two Months before the Date of the above Letters.