munroe performed a petrographic examination. is the term used for identification of minerals. concrete is made of sand, cement, water, and pieces of stone, which is poured into molds to form the bumper blocks. as it dries, the mix design settles into a distinctive pattern, which is visually different in each concrete block. when munroe compared the murder weapon to the other concrete pieces found in the schoolyard, the mix, design, and position of the stones were identical. >> the fit was almost like a glove. when you get broken aggregates, in your sand and gravel inside your concrete, it will break and form an irregular surface and you'll have classes that will break out of the concrete mold and what you do is try to fit that in. and it's not just one fit. it's a collection of fits. >> munroe suspected that the murder weapon might contain a fingerprint. but lifting a print from a porous surface like concrete is extremely difficult. >> it is almost like a fingerprint is sitting on top of a bed of nails. so your latent material w

, munro, and more munro. i'm a legacy president everything he did i will do and i will be, he uses the term a strict construction list, which is a bit of a nod nod wink wink i'm not challenging slavery. its first annual address, saving the union where use this word improvement all the time, this is a very different vision of the government. he stop saying i'm just going to do what munro did and is about 35 different policies he's going to roll out which gets a lot of southerners very nervous wreck quickly. let me backtrack for one second. i think the most important moment for answering the question comes in 1820. so in 1820 this question of missouri's dissension of the union will be debated. it is being debated and the most important question that comes up is is is a quincy slave or free? can the federal government control and dictate what it will be? the way things are done and president abbas at the time is there's only one party so cabinet secretaries really are meant to be indicative of different parts di

. >> when did munro trotter get wind of the movie and how well did he know woodrow wilson? >> that is to questions. let me start with wilson. i love the fact there's connective tissue between wilson and griffith which would already mentioned in terms of the screening. a couple must before in the end of 1914 trotter had an encounter with wilson in the white house that i think he juxtaposed, it says everything about the dynamic here. trotter supporting wilson in 1912 for the presidency. by 1914, he and many black leaders in the country were appalled by the jim crow in the federal government. trotter and assistant an audience with the president -- insisted on an audience with the president import all of the strings to get into the white house which he did. he presented the president with a huge petition and confronted him in a very firm, trotter lightweight about segregation in the federal offices about what a the trail it was. wilson, it soured so fast, wilson cannot believe a black man was talking to him in this way. essentially, if actively he told trotter to stop and noble

the civil war and efforts by african-american civil rights advocate and newspaper publisher william munrotter to prevent the movie's release. >> par two of the movie after the war, reconstruction, is really the heart of the protest in the sense that this is where the blacks are appalled by the betrayal of freed slaves. this is the scene showing what happens when you give former slaves the right to vote, the right to be elected, the right to govern. it is a scene in the south carolina legislature where there first and primary order of business is to pass a bill allowing for interracial marriage. in griffith's hands, black men are solely interested in pursuing and having white ♪ >> author did glare on the controversial story behind birth of a nation. tonight on q&a. up next, a discussion about the 20th century birth control advocate market -- margaret sanger. we will hear from a panel of historians, activists, and her grandson. they discussed the impact of race class, and politics

although i guess munro is pretty close. reagan does pretty well. at any rate, good question. yes, sir. >> wait for the microphone please. >> sorry, i forgot to say that. >> i wondered if you could explain a little bit more about the jay treaty -- explain a little bit more -- [inaudible] >> the jay treaty? their argument was the treaty called for certain conditions to be created. one of them had to do with adjudicating american debts pre-war debts, so the idea was that if you denied the appropriation for the commission to be formed, you could stop the treaty from even being implemented. the treaty has already been ratified already been agreed to. they are basically trying to sort of mess it up and make it so that the british will get mad and reject it, is kind of their idea. but it is a shred. it's one of those moments though, when the constitution -- you know the constitution is really being written in the 1790's. i really think the real constitution is written in the early 19th century when things that are spelled out one way -- they could have easily gone -- republicans alm