The picture below shows a larger front and back view of this Old WashingtonD.C. Fireman or Fire Department Brass Metal Uniform Button. This button is not dated and the year that it was made is unknown. It has an image of the Capitol Building, and it is marked on the two sides as follows:
DC FD S. N. MEYER WASHINGTOND.C.
The button measures about 7/8'' wide. It appears to be in mint condition as pictured.