New York, Aúg 31. Riehmoiid papers of the 29th cont-iin the iollowing: Sis huudred Yankee cavalry advauced up the Península on Thursday as far ns New Kent Court House, and a detaclnm-nt came up later in the day to the vicinity of Bottom's Bridge, over the Chickiiliominy, h'fteen miles below Richnïond. At tbis point they exchanged a few shots wlth our pieke's, and it is said several on eaoh side were killed and wounded. We do Dot think much blood was ipilled. Our picfcetë were, however, drivon in,but, before retiring. thcy removed the floor' of tl %fl Brtd preVented the further alvance of the cnemy n thaf dircctinn. It is by.no meaus certain tliat tho Yankees designed to cxtend their reconnoissance this side of the Chickahominv, r.s thoy made no attempt to do so, but rturned down the Península. Whëther fliey came from Williamsburir, nv feére fa Í4éd iVoin transports at the Whi'e House, we Inve DOt ascertained. An officer of Qüü: E. Etzy's staff, who returned yeSterclay evening from a scout as far is Ñew Kont Court House, reports he saw no indira tious of a hostile force, but was informed at the Court House that six hundred had visited that place on Tbursday. The streugth of the invador-t was greatly exapgerated by first reports wbich reached the city.