THE EXACT MILWAUKEE TIME. – Col. GRAHAM sent yesterday “to the Newhall House and Sentinel,” with his compliments, the exact Milwaukee time by telegraph from Chicago, which the Colonel took considerable pains to get accurately, for which our people at large are placed under obligations to him. According to Col. GRAHAM’S computations our regulators here were from 59 seconds to 10.5 minutes behind the correct time, that of Newhall House varying the most from the true time. There is a difference of one minute and twenty-eight seconds between the true time in this city and the city of Chicago, so that if our regulators are kept according to Col. GRAHAM’S computations, by which the Chicago standard of time is regulated, the time in the two cities will be near enough alike for all practical purposes. Messrs. LOOMIS & HOES’ regulator was nearest the correct time, lacking only 59 seconds. They now have the true time, which the Newhall House regulator also corresponds.