RICHMOND, September 12. The public mind has been much involved in dangerous apprehensions, concering an insurrection of the negroes in several parts of the adjacent counties...Such a thing has been in agitation among the blacks, principally instigated by an ambitious and insidious fellow, a slave, by the name of GABRIEL, the property of Mr. Thomas Prosser, of the county of Henrico. This villain, assuming to himself the appellation of General, through his artfulness, has caused some disturbance, having induced many poor, ignorant, and unfortunate creatures to share in his nefarious and horrid design. This plot which has been so deeply planned, and long matured, is, we hope, entirely exploded. Thirty or forty of the party have been arrested and confined in jail for trial. Yesterday a called court was held for that purpose, at the court house in this city, when six of them were convicted on the strongest evidence and condemned to suffer death, this day. It is said that the evidence which has been procured, will go to prove nearly the whole of them guilty. To day the court will proceed to go thro' with the rest of the trials. By the Governor of the Commonwealth of Virginia. A Proclamation. WHEREAS there is good reason to suspect that GABRIEL, a negro slave the property of Thomas H. Prosser, has been concerned in exciting an insurrection of the negroes against the commonwealth, and who hath absconded from justice. I have thought fit with the advice of the council of state, to issue this Proclamation, hereby offering a reward of THREE HUNDRED DOLLARS, to any person or persons who shall apprehend and convey to the jail of the county of Henrico the said negro slave GABRIEL, to the end that he may be tried for the said crime. And whereas it is presumable that some of the accomplices of the said GABRIEL may have repented of the part they have borne in the said conspiracy and be disposed to make some attonement therefor, with a view to confirm them in that disposition. I do hereby offer in addition to the above reward, to any number not exceeding five of the said accomplices, who shall apprehend the said GABRIEL and deliver him up so that he be brought to justice, a full pardon for their said offences. All officers civil and military within their respective deparments, are hereby required, and the good people of the commonwealth exhorted use their best endeavours to apprehehend [sic] and convey the said negro slave GABRIEL to the jail aforesaid. Given under my hand and under the seal of the Commonwealth, at Richmond, this 9th day of September, one thousand eight hundred. JAMES MONROE. N.B. GABRIEL is a negro of a brown complexion, about 6 feet 3 or 4 inches, a bony face, well made, and very active, has two or three scars on his head, his hair very short, and has lost two front teeth. He can read and write, and perhaps will forge himself a pass, or certificate of his freedom, he is 24 or 25 years of age, but appears to be about 30.