rectingthem to place flags on their buildings athaif mast for thirty days .IHE XELLOW|FEVEB AT PENSACOLA.The acting secretary of the navy has received the following telegram from Lieut.Welch, commanding the Pensacola navyNO. 233.yard, which was dated yesterday : Thetotal cases of yellow fever at the navyyard to date is six, including Surgeon Owens and Child?.