Fast Riding.
--Several instances of danger arising to citizens from the too common practice of urging steeds through the streets at an unlawful rate of speed having been reported to the Mayor, the police have received instructions to make all riders on horseback and drivers of vehicles comply strictly with the ordinance on the subject, which prescribes six miles per hour as the rate at which one may legally propel himself through the streets. Warrants were yesterday issued by the Mayor against two parties charged with fast driving.