Outrageous proceedings of the Federalists in Baltimore — arrest of the Board of Police.
Baltimore, July 1.
--Since 2 o'clock this morning, startling proceedings have occurred.
Detachments of artillery and infantry have been posted on Monument Square and the Exchange Place, and in the Eighth Ward on Broadway, and at other points.
Before day-light, all the members of the Board of Police, except the Mayor, were arrested.
It is said that these proceedings were instituted by Gen. Banks, in consequence, as he regarded, of the discovery of a plot against Federal supremacy in Baltimore.