The citizens of Baltimore have obtained a boon, in the shape of one of Berdan's meehanical bakeries, which opened there a few days ago. At the opening, some six hundred persons were present, and the president, William Norris, Esq., set forth in a neat "peech the advantages to be derived from this invention. Mr. Berdan replied, and made some practical remarks, which were responded to, on behalf of the citizens, by Judge Lee.