July 1942. "Production. Machine guns of various calibers. Agnes Mahan, bench lathe operator at a large Eastern firearms plant, makes oil drills for .50- caliber machine gun barrels. Colt's Patent Firearms Mfg. Co., Hartford, Connecticut." Photo by Andreas Feininger for the Office of War Information. View full size.

Washington, D.C., circa 1925. "Rear view of Potomac Electric Power Co. Benning plant." 8x10 safety negative by Theodor Horydczak. View full size.

December 1942. "Bridge with five-ton coal bucket, Milwaukee Western Fuel Co." Photo by Jack Delano for the Office of War Information. View full size.

May 1943. "Bethlehem-Fairfield shipyards, Baltimore, Maryland. Liberty ship construction. Welding on a hatch assembly at night." Medium format negative by Arthur Siegel for the Office of War Information. View full size.

Circa 1910. "Edison Electric plant (Detroit Edison Company), Detroit, Michigan." 8x10 inch dry plate glass negative, Detroit Publishing Company. View full size.

1906. "Great Lakes Engineering Works, Ecorse, Michigan. Steamer James Laughlin at left." Now where'd I put that instruction sheet? View full size.

June 1941. "Parker Dam power project. View from California side into Arizona." Gelatin silver print by Ben Glaha, Bureau of Reclamation. View full size.

Cincinnati, Ohio, circa 1906. "New pumping plant on Ohio River." 8x10 inch dry plate glass negative, Detroit Publishing Company. View full size.

Ypsilanti, Michigan, circa 1900. "Water tower." 8x10 inch dry plate glass negative, Detroit Publishing Company. View full size.

Trade Show. Location unknown. View full size.

November 1942. "Phillips gasoline plant. Borger, Texas. Storage tanks." Medium-format negative by John Vachon, Office of War Information. View full size.

July 10, 1937. "Testing cosmetics. The Department of Agriculture is making tests every day in order to get cosmetics under the Pure Food and Drug Act. Mrs. C.W. West, seated, is helping Mrs. R. Goodman make a test on cold cream and other facial creams." Harris & Ewing Collection glass negative. View full size.

Every photo needs a caption, please. View full size.

"Gas tank at 26th & G." The city gas house and holding tanks ("gasometers") in Northwest Washington near the current location of the Watergate complex. The intersection in the photo (seen earlier here) is New Hampshire (middle left) and Virginia avenues. Harris & Ewing Collection glass negative. View full size.

Washington, D.C., circa 1917. "Washington Gas Light holders at 26th and G streets N.W." These relics of the gaslight era ("two of Washington's biggest stinkers") were scrapped around 1947. Just about every city of any size in the latter half of the 19th century had its "gashouse district" -- a rough neighborhood dominated by smelly holding tanks for the municipal gas plant, where coal was gasified to make "city gas" (generally either "coal gas" or "water gas," depending on the process) for illumination. Harris & Ewing Collection glass negative. View full size.