New York, Aug. 7. Tho Tribune's special says : ''The following are our latest advicca from Sperryville. Eiglit prisoners lisr0 just been brought in from Mndivn. Th reo of thuin iiud been in tho retó araiy at Richmond. Lo val blacks are coming into tig line in great nurnbers in tbo dire tii:n of Stanardsville. Tdoy uru of a vory superior olass, and wül inake excellent teamsters. A scouting party yesterday iound botween Liranty ::nd thirly negroes in irons about twelve miles from Madison iu a nenrly statved condition. Tbey say tliat they wero cauglit while tryiog to escapo to our lines, and placed in irons. " Tommy, what is longitudö?" " A olothes line, father," " Prove it, Tommy." ' Because it stretuhes from pole to poje," baid yonng liopeful.