IN the summer of 1791, several gentlemen of distinction in the state of New-York, made a tour through its western territory. In their progress along the east bank of the Seneca river, six miles south of Cross and Salt lakes, and forty miles south of the fort of Oswego, they discovered a remnant of ancient Indian defense, unequalled perhaps even by the celebrated vestiges at Muskingum.

The principal fortification is 220 yards in length, and 55 yards in breadth. The bank and corresponding ditch are remarkably entire, as are two appertures opposite each other in the middle of the parallelogram, one opening to the water, and the other facing the forest.

About half a mile south of the greater work, is a large half moon, supposed to be an out-work; but attended with this singularity, that the extremeties of the crescent are from the larger fort. The banks and ditch, both of this and the first fortress, are covered with trees which exhibit extremity of age.

Over a small elevation in the great fort the gentlemen observed a flat stone, five feet in length and three and a half feet in breadth, and six inches thick, which was evidently a sepulchral monument. There were a number of figures engraven upon it, by being sunk with a chissel near half an inch lower than the general surface of the stone. The following exhibits its appearance -- perhaps more like the unmeaning crawling of a snail, than the hieroglyphics of ancient moralizing Thebes.

Upon removing the stone, one of the gentlemen with his cane dug up a piece of an earthen vessel, which from the convexity of the fragment he supposed might contain two gallons: it was very well burned -- looked red, and had its upper edge indented, as with the finger in its impressionable state.

It is remarkable, that in the enquiries the travellers made concerning these singular constructions, among the surrounding Onandagoes and other nations, they were so far from receiving any information, traditionary or otherwise, that the natives themselves had never noticed it.