IN: Mary Ann Todd Lincoln (December 13, 1818 - July 16, 1882) was the wife of the 16th President of the United States, Abraham Lincoln, and as such the First Lady of the United States from 1861 to 1865. She dropped the name Ann after her younger sister, Ann Todd [Clark], was born, and did not use the name Todd after marrying. Mary was a member of a large, wealthy Kentucky family, and was well educated. After finishing school during her teens, she moved to Springfield, Illinois, where she lived with her married sister Elizabeth Edwards.

Mary was born in Lexington, Kentucky as the fourth of seven children of Robert Smith Todd, a banker, and Elizabeth "Eliza" (Parker) Todd. Her family were slaveholders, and Mary was raised in comfort and refinement. When Mary was six, her mother died in childbirth. Two years later, her father married Elizabeth "Betsy" Humphreys and they had nine children together. Mary had a difficult relationship with her stepmother.  From 1832, Mary and her family lived in what is now known as the Mary Todd Lincoln House, an elegant 14-room residence at 578 West Main Street in Lexington, Kentucky.  Mary's paternal great-grandfather, David Levi Todd, was born in County Longford, Ireland, and immigrated through Pennsylvania to Kentucky. Another great-grandfather, Andrew Porter, was the son of an Irish immigrant to New Hampshire and later Pennsylvania. Her great-great maternal grandfather Samuel McDowell was born in Scotland, and emigrated to Pennsylvania. Other Todd ancestors came from England.  At an early age Mary was sent to Madame Mantelle's finishing school, where the curriculum concentrated on French and literature. She learned to speak French fluently and studied dance, drama, music, and social graces. By age 20, she was regarded as witty and gregarious, with a grasp of politics. Like her family, she was a Whig.  Mary began living with her sister Elizabeth Porter Edwards in Springfield, Illinois in October 1839. Elizabeth, married to Ninian W. Edwards, son of a former governor, served as Mary's guardian. Mary was popular among the gentry of Springfield, and though she was courted by the rising young lawyer and Democratic Party politician Stephen A. Douglas and others, she chose Abraham Lincoln, a fellow Whig.

Did she get along well with her siblings?

OUT: 


IN: Slotin was the first of three children born to Israel and Sonia Slotin, Yiddish-speaking refugees who had fled the pogroms of Russia to Winnipeg, Manitoba. He grew up in the North End neighborhood of Winnipeg, an area with a large concentration of Eastern European immigrants. From his early days at Machray Elementary School through his teenage years at St. John's High School, Slotin was academically exceptional. His younger brother, Sam, later remarked that his brother "had an extreme intensity that enabled him to study long hours."

On 21 May 1946, with seven colleagues watching, Slotin performed an experiment that involved the creation of one of the first steps of a fission reaction by placing two half-spheres of beryllium (a neutron reflector) around a 3.5-inch-diameter (89 mm) plutonium core. The experiment used the same 6.2-kilogram (13.7 lb) plutonium core that had irradiated Harry Daghlian, later called the "demon core" for its role in the two accidents. Slotin grasped the upper 228.6 mm (9-inch) beryllium hemisphere with his left hand through a thumb hole at the top while he maintained the separation of the half-spheres using the blade of a screwdriver with his right hand, having removed the shims normally used. Using a screwdriver was not a normal part of the experimental protocol.  At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "prompt critical" reaction and a burst of hard radiation. At the time, the scientists in the room observed the blue glow of air ionization and felt a heat wave. Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. He jerked his left hand upward, lifting the upper beryllium hemisphere and dropping it to the floor, ending the reaction. However, he had already been exposed to a lethal dose of neutron radiation. At the time of the accident, dosimetry badges were in a locked box about 100 feet (30 m) from the accident. Realizing that no one in the room had their film badges on, "immediately after the accident Dr. Slotin asked to have the badges taken from the lead box and placed on the critical assembly". This peculiar response was attributed to "vertigo" and was of no value for determining the actual doses received by the men in the room.  Others in the room at the time included Raemer E. Schreiber, Alvin Cushman Graves, Stanley Allan Kline, Marion Edward Cieslicki, Dwight Smith Young, Theodore P. Perlman, and Pvt. Patrick J. Cleary.  As soon as Slotin left the building, he vomited, a common reaction from exposure to extremely intense ionizing radiation. Slotin's colleagues rushed him to the hospital, but the radiation damage was irreversible.  By 25 May 1946, four of the eight men exposed during the incident had been discharged from hospital. The Army doctor responsible for the hospital, Captain Paul Hageman, said that Slotin's, Graves', Kline's and Young's "immediate condition is satisfactory."

What was the critical accident?

OUT:
At 3:20 p.m., the screwdriver slipped and the upper beryllium hemisphere fell, causing a "prompt critical" reaction and a burst of hard radiation.