private schools following the world war ii baby-boom. and are interview with billionaire philanthropist david rubenstein. get our complete schedule at c-span.org. >> during the great depression in world war ii, photographers working for the u.s. government were assigned to travel the u.s. and document living and working conditions and later war production efforts. in 1939, the photographers began using kodachrome color film. library of congress curator tells us about the story of the collection and the photographers. >> we are in the center of both of the photographs division of the library of congress. --center of the vault. the library has a collection of color photographs from the 1940's and 1930's. it started as an experiment with color film. kodak was just putting its color film on the market, and center dot two photographers, institutions -- sent it out to photographers, institutions, to try and create a market for it. the pictures were free, so they were appealing to newspapers, publishing agencies, book publishers, that kind of thing. i was already familiar with the black and white photograph. there are about 171,000 from security ministrations and office of war information black-and-white photographs. i have been working with those for a few years. there was not much evidence placed on color transparency. they were hard to handle. they were unique items. there was only one of each at theime, in the 1970's. it was really difficult to make the copy. it was very expensive to make a photograph. you had to make another print from the color transparency. people didn't want to pay that extra money. shelf for sat on the a long time. and then, sally stein, who is a photo historian, began doing a project about color film. she came to the library, wanted to see these color transparencies. i was one of the people who helped serve her. at the time, the library didn't that made it affordable for researchers. she brought a photographer with her to make copies on a stand set up in our division. i became intrigued, began looking at them more and more. initially i thought, these are interloper pictures. they don't really belong. it took a while for me to realize they did belong. there are pictures made of things, outings, the photographers would carry a 35mm camera. camera loadedry with color film. not just like in white. -- not just black and white. they would use these interchangeably. there are some black and white photos that are near duplicates of the color photos you can find in the 1930's and 1940's set. >> up next, dana show talks about the history of the bayonet and how it affected its use in the civil war. ofdescribes a difference opinion between civil war and an enlisted men on if the bayonet to be used in battle. the editor and