Essays on the history of watch cases



  Sundial

The most common  hronometricheskim the device can be regarded as a solar clock, based on a seemingly daily, and sometimes the annual motion of the Sun. There are those hours are not used to understand the relationship between man and the length of the shadows of objects. But even realizing it, hardly anyone rushed to build a clock, it was necessary to further understand that such a time. We know that in its original form had a form of sundial obelisk, but the exact date of their occurrence is unknown. And by the way, they could invent in different places.

The traditional story is of the opinion that the first mentioned sundial Chinese Chiu-pi (about 1100 BC). In his manuscript, he said that with their help, the Chinese are easily installed height of summer and winter sun, and identified the ecliptic inclination of 23 ° 52 '. However, it is not clear how they merili, since many of the knowledge necessary to do so - in particular, trigonometry, - appeared much later. And why did they do that, too, is unclear. Suppose because of China's innate curiosity. And until recently, the Chinese thought their country median empire, covered dome of the sky, and no representations or sphericity of the Earth did not have. The most favorable climatic conditions for the measurement of time using the sundial is Egypt, and more reliable to the view that the early sundial -- gnomon, a vertical obelisk with the scale marked on the ground beside him - there is here. Obelisk served concurrently to worship the cult of the god of the Sun. These sacred obelisks stood, as a rule, go into the temple. Interestingly, the tradition of installing a solar clock at the temples can be traced in Europe until the XIX century. But in Russia do not always sunny, so we gather the faithful in temple battle bells.

So far, survived the Egyptian obelisk in the height of 34 meters. It is believed that in the reign of Augustus, he was transported from Egypt to Rome by the emperor and installed on the Field of Mars, and supervised the operation mathematician Fakundus Novuss. Gnomon placed in the center of the ad hoc panel, which draw a clock face, time lines have been laid out from the brass parts. According to Pliny the Elder, the obelisk was used to determine the time of year and longitude of the day. He prostoyal several centuries, but in an era of decadence of ancient Rome was dropped and long forgotten. In 1463 it once again found, but only in 1792 once again established on the area Montechitorio in Rome, where he is today.

In addition to Egypt, obelisks were set up and other construction sundial. For example, consisting of the horizontal part - hronometricheskoy line with the scale length of about 30 cm - and perpendicular to it «shoulder», casting its shadow on the scale. Yet there were hours of step with the two inclined surfaces oriented along the axis of east-west, and divided into stages. At sunrise the shadow fell on the edge of the upper rung of one of these surfaces, the east, and then gradually dropped, and by noon had disappeared. Afternoon shadow once again appears at the bottom of the western surface, where it rises, until at sunset is not related to the brink of the upper step. In these hours of time determined by length rather than the shadow area.

Measuring the length of time the shadows here and there remained until the late Middle Ages. The physician and geographer Paolo Toskanelli built in 1468-1482 years in the church. Maria de Fiore in Florence Dwarfs height 84.5 meters, with the help of which have been able to measure with precision polusekundnoy local noon. With the help of the gnomon Toskanelli specified data of astronomical tables.