According to constructmaterials, the beginnings of calendar calculations and astronomy go back to ancient Egypt. The civil or change year, which presumably replaced an older year based on lunar cycles, was set with its beginning (New Year) at the time of the annual flooding of the Nile, the Nile weir, which is important for agriculture, the beginning of which is due to the early rise (» heliacal rise ”) announced by Sirius (Greek Sothis, Egyptian Sepedet) after being invisible for 70 days. This led the Egyptians to a year of 365 days, which they divided into 3 seasons with 4 months each of 30 days and 5 additional days, the Epagomenen (Egyptian heriu-renpet, “those on the year”). Since this year at 1 ⁄ 4Day behind the astronomical solar or Sothis year, the beginning of a new year is postponed every four years by one day from the originally determined New Year’s day. Since no leap day was introduced, the seasons lagged behind the established civil calendar more and more over the centuries until they had completely passed through the calendar in the period of 1,460 years (Sothis period), so that the astronomical and civil New Years coincided again. Such a collapse (apocatastasis) took place according to the Roman writer Censorinus Held in 139 AD. Nevertheless, from this fixed point, further apocatastases in the previous millennia cannot be determined without further ado, but only with the help of astronomical calculations, and Egyptian details of the rise of Sothis can only be used chronologically under certain conditions, so that absolute time details remain controversial despite the Sothis dates that have been preserved.
The months of the civil calendar were each divided into 3 weeks of ten (decades), to which 36 stars, groups of stars or constellations near the equator (deans) were assigned. The current deans (and night hours) could be read from the dean lists as a calendar. The oldest lists come from the inside of the coffin lid from the burial ground of Siut (9th / 10th dynasty, 22nd / 21st centuries), later also from the ceilings of graves; they have only been handwritten since the Hellenistic period. In addition to the decades, the 5 leap days were also assigned constellations; like the deans, they were regarded as gods and rulers over the periods of time assigned to them. The zodiac, on the other hand, did not appear in Egypt until the 3rd century BC. Chr.; it is borrowed from Mesopotamian astronomy. – The division of the day into 2 × 12 hours can first be demonstrated in Egypt, whereby light day and corresponding night were divided into 12 sections. The hours were therefore unevenly long depending on the season and geographical latitude. Sundials were used for the day and water clocks (inlet and outlet clocks) for the night. A water clock with a scale for all months of the year was made by Amenemhet at the beginning of the 15th century BC Invented and built according to the same rule in the 3rd century AD (oldest surviving specimen from the time of Amenhotep III, around 1388-1350 BC).
Astronomical images on ceilings were more common in the New Kingdom, including in the former Osireion of Seti I in Abydos. They are based on scientific observations and astronomical textbooks, of which only a few titles are known. The Carlsberg Papyrus No. I in Copenhagen from the Roman Empire (2nd century AD) transfers and comments on the inscriptions on this image of the sky.
Similar to stargazing, the mathematics of the Egyptians was also geared towards practice and proceeded according to empirically found rules. The number system was an additive decimal system with individual characters for powers of ten from 10 0 to 10 6, e.g. B. dashes for one, ∩ for ten, 9 for hundred. There were (besides 2 ⁄ 3 and occasionally 3 ⁄ 4) only stem fractions into which individual fractions were to be resolved. Addition and subtraction of whole numbers were carried out by combining two numbers and re-bundling, multiplication by successively doubling the multiplicand and subsequent addition of the partial products (division vice versa). The most important mathematical papyri with collections of exercises are the “Moscow Papyrus” from the 13th Dynasty (25 geometric and stereometric tasks of daily life) and the “Papyrus Rhind” from the Hyksos period, which, however, goes back to the Middle Kingdom (Ahmose). A leather roll from the Hyksos period contains a number of broken tree breakdowns as a table. Papyri from the Roman and Byzantine periods show that arithmetic techniques have not changed since the Middle Kingdom. The tasks are essentially based on practice (field surveying, commercial and administrative practice). Geometrical and stereometric calculations were carried out according to certain rules that were found empirically; they are therefore mostly only approximations, e.g. B. the algorithm for calculating a circular area with the modern rule A = (8 ⁄ 9 d) 2, which takes the approximate value (16 ⁄ 9) 2 = 3.1605 for π results. – In addition to the practical tasks, there are occasionally also general tasks.
In mechanics, the Egyptians do not seem to have got beyond the use of simple machines (lever, roller, wedge, inclined plane); The invention of the “Egyptian snail” for irrigation, ascribed to Archimedes, appears relatively late. The major technical achievements (pyramids, obelisks, canals) were probably only possible with simple means and due to the excellent organization of the work processes.
Chemical technologies were also based on thousands of years of experience and the transmission of knowledge . One of the earliest processes here is heat treatment (thermochemical processes), for example for the manufacture of ceramics. Since the early 3rd millennium, the basic materials for glass production, e.g. B. for glazing techniques, the production of Egyptian faience, frits i.a. in use and since the 15th century BC. The sand core technique for the production of glass vessels is known. Added to this are the diverse recipes for the production of valuable dyes such as the synthetically produced Egyptian blue and other pigments from inorganic and organic substances. The great metallurgical knowledge in the extraction, smelting and processing of metals and their alloys was also important for progress.
The Egyptians achieved great achievements in medicine. Imhotep is considered the oldest doctor(around 2650 BC), who is also known as the builder of the first pyramid; he was later worshiped as the god of medicine. The main evidence of the Egyptians’ medical knowledge, which was highly respected in antiquity, is, in addition to representations and preserved medical instruments and mummies (for modern anthropological and medical studies), in particular the various medical treatises. The oldest known manuscript is the “Papyrus Kahun” from the 12th dynasty from the beginning of the 2nd millennium BC. With gynecological treatments and a veterinary text. Other texts are the “Papyrus Brugsch” and the “Papyrus Ebers” (16th century BC; in the Leipzig University Library). It is a kind of recipe manual for the use of several hundred remedies (all three kingdoms of nature) and contains 877 different individual texts. The “Papyrus Edwin Smith” (17th century) contains the surgical treatment of 48 (originally more) cases of injuries (broken bones, contusions, dislocations), progressing from the head to the lower parts of the body. The examination with the symptoms, diagnosis and treatment (the latter divided into statements on treatability) are given for each case. The material of the papyri is z. Some of them are much older and go back to the first dynasties. The many doctors specializing in individual body parts are characteristic of Egyptian medicine. Cleansing ideas led to the frequent use of laxatives and emetics. Anatomical knowledge was little.