and now is the time to meet that challenge. good night, and godspeed to you all. [applause] ♪ [captioning performed by the national captioning institute, which is responsible for its caption content and accuracy. visit ncicap.org] [captions copyright national cable satellite corp. 2016]

>> road to the white house read wind airs every sunday. we will air highline -- highlights back to 1948 from democratic conventions and republican conventions. only on c-span3. you are alone -- looking at a time lapse video showing the process of constructing the exhibition, jacob rees revealing how the other half -- we visit the exhibit in the library's thomas jefferson building to learn about the life journalist, social reformer, and photographer. >> my name is bonnie yochelson.

i wrote the complete collection catalog of riis' photographs published on the occasion of this exhibition. my engagement with the collection started in the 1980's when i was curator of the museum of the city of new york which owns his new york photographs. there is a great paradox to riis' photographs. he was a journalist and celebrity. he saved all of the documentation of his career. he wanted to be remembered for posterity. he created scrapbooks, he saved his manuscripts. every scrap of paper. he abandoned his photographs because he did not think they were of any value apart from his words, arguments, articles, and publications. the way they were discovered is really a fascinating story. riis died in 1914. in the 1940's, a photographer named alexander alland noticed in riis' book that on the title page it says "with illustrations after photographs by the

author." he said to himself, where are these photographs? after several years of searching, he tracked down rii'' son and with much coercing, got his son to try to find the pictures which turned out to be in the attic of his family's home in queens, new york, that was about to be torn down. his son discovered a box filled with 400-odd negatives, 300-odd lantern slides, and almost 200 paper prints and delivered them to alexander alland, the photographer. taking a couple of years, he created an exhibition from the negatives, making beautiful prints from the negatives and working with the curator with the museum of new york to put on an exhibition called "battle of the slums."

it established riis as an important photographer. that is how he entered the history of photography. my problem is a curator in the 1980's was, we don't have prints to show because those almost 200 -- again, the paradox about riis is that he himself said he was a photographer after a fashion. in other words, he was not a real photographer. he used the camera for very few years, less than 10 years. he only took about 300 pictures. about a third of which were family snapshots and other things not of historic importance. his most famous picture today is "bandit's roost" which shows a couple of italian toughs wearing bowler hats. the picture was copied by martin scorsese in a movie, gangs of new york. it is kind of an iconic image. when he first had the idea to use photographs to illustrate the slums in 1887, he reached

out to a friend that was a photographer and found two photographers who were interested in flash. flash photography was the reason he had the idea to even use photographs at all. he was a writer, journalist, writing in the daily newspaper about the conditions in the slum. he read in the newspaper in 1887 that there was this new invention of flash powder that could eliminate the darkness and he said, a ha! he worked with two other photographers who were serious amateurs interested in flash, interested in the technology. among their photographs is "bandit's roost" which was taken with a stereoscopic camera with two lenses. there are actually two images,

but that one is the most famous image. >> the exhibition can be viewed online at the library of congress website. loc.gov. next, military historian paul springer talks about the use of cutting-edge technology in the united states military. robotic weaponry and warfare such as drones and artificial intelligence have revolutionized military affairs, making previous tactics obsolete. the new york historical society hosted this 90-minute event. >> it is a pleasure to introduce my colleague and friend paul springer, who is a senior fellow d