Problem: "Cross Road Blues" (also known as "Crossroads") is a blues song written and recorded by American blues artist Robert Johnson in 1936. Johnson performed it as a solo piece with his vocal and acoustic slide guitar in the Delta blues-style. The song has become part of the Robert Johnson mythology as referring to the place where he supposedly sold his soul to the Devil in exchange for his musical talents, although the lyrics do not contain any specific references. Bluesman Elmore James revived the song with recordings in 1954 and 1960-1961.

A crossroads or an intersection of rural roads is one of the few landmarks in the Mississippi Delta, a flat featureless plain between the Mississippi and Yazoo rivers. It is part of the local iconography and various businesses use the name, such as gas stations, banks, and retail shops. A crossroads is also where cars are more likely to slow down or stop, thus presenting the best opportunity for a hitchiker. In the simplest reading, Johnson describes his grief at being unable to catch a ride at an intersection before the sun sets. However, many see different levels of meaning and some have attached a supernatural significance to the song. Both versions of the song open with the protagonist kneeling at a crossroads to ask God's mercy, while the second sections tells of his failed attempts to hitch a ride. In the third and fourth sections, he expresses apprehension at being stranded as darkness approaches and asks that his friend Willie Brown be advised that "I'm sinkin' down". The first take of the song, which was used for the single, includes a fifth verse that is not included in the second take. In it he laments not having a "sweet woman" in his distress. The song has been used to perpetuate the myth of Johnson selling his soul to the Devil for his musical ability. The lyrics do not contain any references to Satan or a Faustian bargain, but they have been interpreted as a description of the singer's fear of losing his soul to the Devil (presumably in exchange for his talent). Music historian Elijah Wald believes that Johnson's verses do not support the idea. Delta bluesman Tommy Johnson promoted himself as having made a deal with the Devil and Southern folklore identifies a crossroads or graveyard as the site of such a pact, which Wald identifies as likely sources of the myth. However, musicologist Robert Palmer points out that Johnson was "fascinated with and probably obsessed by supernatural imagery." His song "Hellhound on My Trail" tells of trying to stay ahead of the demon hound which is pursuing him and in "Me and the Devil Blues" he sings, "Early this mornin' when you knocked upon my door, and I said 'Hello Satan I believe it's time to go'". These songs contribute to the Faustian myth; how much Johnson promoted the idea is debated, although many agree "the 'devil angle' made for good marketing". Blues historian Samuel Charters sees the song as having elements of protest and social commentary. The second verse includes "the sun goin' down now boy, dark gon' catch me here", a reference to the "sundown laws" or curfew during racial segregation in the United States. Signs in the rural South advised "Nigger, don't let the sun set on you here". Johnson may be expressing a real fear of trumped up vagrancy charges or even lynchings that still took place. Others suggest that the song is about a deeper and more personal loneliness. Writers Barry Lee Pearson and Bill McCulloch argue that the fifth verse in the single version captures the essence of the song: "left alone, abandoned, or mistreated, he stands at the crossroad, looking this way or that for his woman".

What happens after he asks?

Answer with quotes: The song has been used to perpetuate the myth of Johnson selling his soul to the Devil for his musical ability.

Problem: Zhang Heng (Chinese: Zhang Heng ; AD 78-139), formerly romanized as Chang Heng, was a Han Chinese polymath from Nanyang who lived during the Han dynasty. Educated in the capital cities of Luoyang and Chang'an, he achieved success as an astronomer, mathematician, scientist, engineer, inventor, geographer, cartographer, artist, poet, statesman, and literary scholar. Zhang Heng began his career as a minor civil servant in Nanyang. Eventually, he became Chief Astronomer, Prefect of the Majors for Official Carriages, and then Palace Attendant at the imperial court.

Zhang Heng is often credited with inventing the first odometer, an achievement also attributed to Archimedes (c. 287-212 BC) and Heron of Alexandria (fl. AD 10-70). Similar devices were used by the Roman and Han-Chinese empires at about the same period. By the 3rd century, the Chinese had termed the device the ji li gu che, or "li-recording drum carriage" (the modern measurement of li = 500 m/1640 ft). Ancient Chinese texts describe the mechanical carriage's functions; after one li was traversed, a mechanically driven wooden figure struck a drum, and after ten li had been covered, another wooden figure struck a gong or a bell with its mechanically operated arm. However, there is evidence to suggest that the invention of the odometer was a gradual process in Han Dynasty China that centered on the "huang men"--court people (i.e. eunuchs, palace officials, attendants and familiars, actors, acrobats, etc.) who followed the musical procession of the royal "drum-chariot". There is speculation that at some time during the 1st century BC the beating of drums and gongs was mechanically driven by the rotation of the road wheels. This might have actually been the design of Luoxia Hong (c. 110 BC), yet by at least 125 the mechanical odometer carriage was already known, as it was depicted in a mural of the Xiao Tang Shan Tomb. The south-pointing chariot was another mechanical device credited to Zhang Heng. It was a non-magnetic compass vehicle in the form of a two-wheeled chariot. Differential gears driven by the chariot's wheels allowed a wooden figurine (in the shape of a Chinese state minister) to constantly point to the south, hence its name. The Song Shu (c. AD 500 ) records that Zhang Heng re-invented it from a model used in the Zhou Dynasty era, but the violent collapse of the Han Dynasty unfortunately did not allow it to be preserved. Whether Zhang Heng invented it or not, Ma Jun (200-265) succeeded in creating the chariot in the following century.

Are there any other interesting aspects about this article?

Answer with quotes:
It was a non-magnetic compass vehicle in the form of a two-wheeled chariot.