In 1853, Dr. Rock came to Boston, where he now resides. On leaving the city of Philadelphia, the professors of the Dental College gave him letters bearing testimony to his high professional skill and integrity. Professor Townsend writes, "Dr. Rock is a graduate of a medical school in this city, and is favorably known, and much respected, by the profession. Having seen him operate, it gives me great pleasure to bear my testimony to his superior abilities." Professor J. F. B. Flagg writes, "I have seen his operations, and have been much pleased with them. As a scientific man, I shall miss the intercourse which I have so long enjoyed in his acquaintance." After Mr. R. graduated in medicine, he practised both of his professions. In 1856, he accepted an invitation to deliver a lecture on the "Unity of the Human Races," before the Massachusetts legislature. In 1857, he delivered the oration on the occasion of the dedication of the new Masonic Temple in Eleventh Street, Philadelphia. His intense application to study and to business had so undermined his health that, in the summer of 1856, he was obliged to give up all business. After several unsuccessful surgical operations here, and when nearly all hope for the restoration of his health was gone, he determined to go to France. When he was ready to go, he applied to the government for a passport. This was refused, Mr. Cass, then secretary of state, saying in reply, that "a passport had never been granted to a colored man since the foundation of the government." Mr. Rock went to France, however, and underwent a severe surgical operation at the hands of the celebrated Nélaton. Professor Nélaton advised him to give up dentistry altogether; and as his shattered constitution forbade the exposure necessary for the practice of medicine, he gave up both, and bent all his energies to the study of law. In 1860, he accepted an invitation, and delivered a lecture on the "Character and Writings of Madame De Staël," before the Massachusetts legislature, which he did "with credit to himself and satisfaction to the very large audience in attendance." _Der Pionier_, a German newspaper, in Boston, said, when commenting on his criticism of De Staël's "Germany," "This thinking, educated German and French speaking negro proved himself as learned in German as he is in French literature." On the 14th of September, 1861, on motion of T. K. Lothrop, Esq., Dr. Rock was examined in the Superior Court, before Judge Russell, and admitted to practice as an attorney and counsellor at law in all the courts of Massachusetts. On the 21st of the same month Mr. Rock received a commission from the governor and council as a justice of the peace for seven years for the city of Boston and county of Suffolk. We annex an extract from a speech made by him before the last anniversary of the Massachusetts Anti-Slavery Society.