مجله تاریخ علم
سال دوم شماره 1 (پیاپی 2، پاییز 1383)

The present article is a survey into the epistemology of thought in the Islamic era. It does not intend to examine the content of the heritage of Islamic thought but to search the structure of the rationality that created it. This rationality is not merely Arabic but some of its constituents are Arabic and some of them are non- Arabic. Moreover, the formation of Arabic Constituents of that rationality were also affected by the Characteristics of non-Arabic cultures.

Periods are the most important parts of the Iranian calendars. During the Achaemenien dynasty the lunisolar 19-year system was in official use. The lunisolar 25-year cycle of intercalation was in use by the Seleucid.At first the Arsacid used the same way of the Seleucid, but then used the solar calendar with the era of the first king of the dynasty. During the Sassanid era the Arsacid calendar became popular in two forms of common civil (or khirājī) and Vahijkik (one month intercalation in every 120 years).The period of leap years in every 120 years during the Sassanid era have been studied by Iranian researchers and orientalists. The doubled intercalary which was two months simultaneously in 461 A.D. during Firūz monarchy (the son of Yesdgerd II, 484-459 A.D.), has been the turning point of intercalary not only in the Iranian calendar but also in other Islamic possessions for about 600 years.The new way of intercalary which was applied in Jalālī calendar is an honor for the Iranian mathematicians and astronomers which found it about 1000 years ago.Unfortunately, there would never be a periodical usage for the leap years, even in the present formal Hejira solar calendar.The 2820-year intercalation period is one of the new innovations which presented by some modern researchers, but its way lacks accuracy and efficiency of the 128-year historical intercalation period.

The length of real solar year has some variations because of different factors, in a way that is very difficult to compute it for each year. The solar calendar, therefore, must be based on the average length of the solar year. This length, i.e. tropical year, is not an integer (365.24219879 days). Thus in solar calendar, we must make use of some special intercalation in order to get the length of calendar year as much close to the length of natural year as possible.The present Iranian calendar is a solar one. But the law is silent about the length of solar year and the method of intercalation, the fact that has brought about discrepancies among the experts in Iranian calendar.Believing in the necessity of accepting the average length of solar year, the author has tried to find the best intercalation and appropriate cycle(s), by using a computer program. As the result of these computations, a 2820-year cycle, with its special system of leap years, is the best possible, since it prepares a cycle for any ideal solar calendar, including the present Iranian calendar. The author claims that this cycle (with its method of intercalation) would put an end to discrepancies among the scholars.

This article provides an edition of the Persian translation of Zīj-i Shustaka written originally in Arabic by an Iranian astronomer, Husayn b MūsāHurmuzī, around 10 centuries ago. Different from most known Zījes, this short treatise does not include many detailed tables. It only has two relatively small tables for calculating the conjunctions and oppositions of the sun and the moon, and the lunar crescent visibility. Using the astronomical calendars of four years prior to the given year, Hurmuzī calculates the ecliptical longitudes of the sun, the moon, and the planets. He actually makes use of the known periods of the motions of the celestial bodies. A preliminary analysis of his methods follows the Persian text. A photo of a very old Arabic manuscript is also provided at the end of the article

Euclid’s Principles, which contains thirteen articles in geometry, was transferred to Islamic world via two translations entitled Hārūnī and Ma’mūnī. The geometry books of Islamic era contain two additional articles by Hypsicles. Avicenna compiled the chapter of geometry of Shifāon the basis of these fifteen articles, and presented his own reasoning.In order to be familiar with Avicenna’s method of reasoning, the proposition of cutting a certain line in extreme and mean ratio will be discussed in this article.

The sexagesimal system, which is considered one of the major fields of arithmetic during the Islamic period, has widely been applied in astronomical calculations up to present. This system is also used in precise mathematical calculations, like deriving the square and cube roots of non-sexagesimal numbers. Muslim mathematicians used sexagesimal numeration system to write decimal place values, before the development of the decimal numeration system to a fully positional one. The sexagesimal numeration system was invented and developed by the Sumerians and dates back to around 2000 B.C.

Writings regarding of the history of general medicine as translations or original works has a long history in our country, but when it comes to the history of specialized medicine less attention was paid. The purpose of this article is to open a narrow path and to motivate the young thinkers to do research.From the time the man began to converse and express wisdom, he spoke about his heart; however he did know the role of neither this part nor its diseases. The theories which have been propounded over the centuries have mostly been incorrect and far from reality.In Babylonian, Assyrian and Egyptian medicine, there have been indirect allusions to myocardial infraction and bacterial endocarditic. The Egyptians and the Chinese in particular have spoke about sphygmology which is one of the first direct physical signs of heart disease. In Hippocrates's writings, the heart muscle and valves are pointed out, but he believed that there was no blood in the arteries.Aristotle was among the first who dissected animals and talked about the circulatory blood. After the birth of Christ and in Romans era, there have been some symptoms of cardiac which retrospectively lead us to the etiology of heart disease. Galen in the second century gives us some information about the circulatory system; also mislead us regarding its physiology.