Two more cases of the surrender of fugitive slaves have occurred in the State of New York during the month. A colored person, living at Poughkeepsie, and named John M. Boulding, was arrested there and brought to New York. Evidence was submitted to Mr. Nelson, a Commissioner under the law of 1850, which showed him to be the slave of Mr. Anderson, of South Carolina, whither he was immediately sent. The other case occurred at Buffalo, where a negro called Daniel was brought before Commissioner H. K. Smith. He was claimed under the tenth section of the act of 1850, a certified copy of the records of a court of Kentucky being produced, as required by that section, to prove him the property of a Mr. Rust. The Commissioner decided that the evidence was sufficient, but a _habeas corpus_ was granted by Judge Conklin of the U. S. District Court, and the case was argued before him. He decided that the tenth section of the law of 1850, could not apply to slaves who had escaped previous to the passage of the law; and as Daniel was alleged to have fled before that time, the evidence provided for by that section was insufficient. He was therefore discharged. This decision is one of a good deal of importance, as it essentially modifies the operation of the law. An election was held in Mississippi, on the 1st and 2d of September, for delegates to a State Convention, to consider what action Mississippi ought to take in regard to the action of the last Congress on the question of slavery. The majority of _Union_ delegates returned was very large; so decisive, indeed, was the result regarded as to the feeling of the State upon the subject, that Gen. Quitman, who was running against Senator Foote, as the secession candidate, immediately withdrew from the canvass. The American Association for the Advancement of Education held, the last of August, a very interesting meeting at Cleveland, Ohio. Many of the most distinguished teachers and friends of Education from widely distant parts of the country were in attendance, and the discussions were of decided interest. The new system of collegiate education recently introduced in Brown University, and adopted in the new University at Cleveland (allowing students to select such studies as they may deem most important to prepare them for their several pursuits in life, and giving them certificates of their actual attainments, instead of the usual diplomas), was thoroughly canvassed, both by its friends and its opponents. The chief defenders of the new system were President Mahan of Cleveland, and Prof. Greene of Brown University. Many other important subjects were also discussed, and the proceedings of the Association generally were such as are adapted to exert a wide and beneficent influence upon the cause of education.