Frederick Douglas, the colored orator, addressed a very respectable, though not large audience, at the Town Hall, on Saturday evening last, on the Unity of the Races. His arguments in favor of a common origin of mankind were very logical, and doubtless deemed conclusive by the great majority of his hearers. He is a fluent and powerful speaker, and commands uninterrupted attention.

On Sunday evening, he lectured at the Congregational Church, to a full house. His subject was slavery, or the slave power in the United States. He failed to handle his subject with the power and ability he displayed in his former lectures, and hence some little disappointment was manifested by the public at the close of the performances. We think Mr. D. is entitled to great respect and to the best wishes of all true lovers of the colored race.