Problem: The phonautograph, patented by Léon Scott in 1857, used a vibrating diaphragm and stylus to graphically record sound waves as tracings on sheets of paper, purely for visual analysis and without any intent of playing them back. In the 2000s, these tracings were first scanned by audio engineers and digitally converted into audible sound. Phonautograms of singing and speech made by Scott in 1860 were played back as sound for the first time in 2008. Along with a tuning fork tone and unintelligible snippets recorded as early as 1857, these are the earliest known recordings of sound.
In what years where phonautograms converted to audible sound?
The answer is the following: 2000s

Problem: The idea of Masonic brotherhood probably descends from a 16th-century legal definition of a brother as one who has taken an oath of mutual support to another. Accordingly, Masons swear at each degree to keep the contents of that degree secret, and to support and protect their brethren unless they have broken the law. In most Lodges the oath or obligation is taken on a Volume of Sacred Law, whichever book of divine revelation is appropriate to the religious beliefs of the individual brother (usually the Bible in the Anglo-American tradition). In Progressive continental Freemasonry, books other than scripture are permissible, a cause of rupture between Grand Lodges.
Most lodges have the oath taken on what?
The answer is the following: Volume of Sacred Law

Problem: Simultaneously with these conflicts, bison, a keystone species and the primary protein source that Native people had survived on for centuries were being destroyed. Some estimates say there were over 13 million bison in Montana in 1870. In 1875, General Philip Sheridan pleaded to a joint session of Congress to authorize the slaughtering of herds in order to deprive the Indians of their source of food. By 1884, commercial hunting had brought bison to the verge of extinction; only about 325 bison remained in the entire United States.
What year did General Sheridan approach Congress about killing bison?
The answer is the following: 1875

Problem: In 1870, after France attacked Prussia, Prussia and its new allies in Southern Germany (among them Bavaria) were victorious in the Franco-Prussian War. It created the German Empire in 1871 as a German nation-state, effectively excluding the multi-ethnic Austrian Habsburg monarchy and Liechtenstein. Integrating the Austrians nevertheless remained a strong desire for many people of Germany and Austria, especially among the liberals, the social democrats and also the Catholics who were a minority within the Protestant Germany.
What did many people in Germany still want to do?
The answer is the following:
Integrating the Austrians