Answer:
According to the Second Amendment, all US citzens were allowed to bear and keep arms. It is not clear whether that provided the right to individual self-defense or to state militias.
Explanation:
The Second Amendment of the Constitution that was adopted in 1791 was meant to provide a check on congressional power and the federal government under Article I Section 8. This is the section of the Amendment that addresses the rights of the individual to organize, arm and discipline the federal militia. This amendment is controversial in modern society today because some people interpret it as the Constitutional defense for an individual to bear arms. It is an important part of the controversy over gun control in the United States.
There is some disagreement about the extent to which this right was applicable because the Second Amendment reads "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." There are therefore some who say that the right to bear arms is only in the context of militias needed to defend the rights of the state.
Ladd-Franklin's mathematical interests ultimately led her to make important contributions to the field of psychology. In 1886, she became interested in the geometrical relationship between binocular vision and points in space and published a paper on this topic in the first volume of the American Journal of Psychology the following year. During the 1891-92 academic year, Ladd-Franklin took advantage of her husband's sabbatical leave from Johns Hopkins and traveled to Europe to conduct research in color vision in the laboratories of George Müller (1850-1934) in Göttingen, and Herman von Helmholtz (1821-1894) in Berlin, where she also attended lectures by Arthur König. In contrast to the prevailing three-color and opponent-color explanations of color vision, Ladd-Franklin developed an evolutionary theory that posited three stages in the development of color vision. Presenting her work at the International Congress of Psychology in London in 1892, she argued that black-white vision was the most primitive stage, since it occurs under the greatest variety of conditions, including under very low illumination and at the extreme edges of the visual field. The color white, she theorized, later became differentiated into blue and yellow, with yellow ultimately differentiated into red-green vision. Ladd-Franklin's theory was well-received and remained influential for some years, and its emphasis on evolution is still valid today.
The Mongol Empire, with its peak size under the rule of Kublai Khan around the year of 1279, included parts of modern Russia in the North, modern day Korea, and modern China in the South on one end of the Asian continent. It stretched through the Asian continent all the way to modern day Hungary in Europe. It also included parts of the modern Middle East such as Iraq and Iran. The total area of the Mongol Empire in its peak was around 40 million km^2.
