مجله تاریخ علم
سال دهم شماره 1 (پیاپی 12، بهار و تابستان 1391)

The use of locks with different forms, mechanisms and applications has been common for a long time in Iran. Among these locks we can point out the pendant combinated lock, in which two mechanisms are used simultaneously in a single body. Employing a descriptive – analytical method, this study searches the reasons of using two mechanisms in these locks. Problems such as: the use of these locks, the reasons of their simple form, the reason for which they are made of steel and are larger than single-mechanism locks, are among the problems discussed in this paper.

The treatise entitled “Arithmetic in astronomy”, which is edited and commented upon in this paper, is part of an old manuscript collection preserved in the National Library of Bosnia and Herzegovina. At the end of this treatise there are some phrases in Arabic which show that the treatise was originally part of a Persian book written by ʿAlī al-Qūshchī. This manuscript is, in fact, an abridged form of the second chapter of Qūshchī’s Book prepared by Naṣrullāh al-Naṣīr bin Naṣīr nicknamed as Wāqif al-Khalkhālī and copied by Ḥājī Uthmān bin Ḥajī ʿUmar. Following the well-known practice of arithmetic books, the treatise contains a breaf discussion of topics such as addition, substraction, multiplication, division and extractactin of the second root in sexagesimal system. Some astronomical applications are also mentioned.

In extant Islamic manuscripts we can find some observation reports of a black dot on the surface of the Sun. These reports add that this dot should be the planet Venus or Mercury, transiting over the Sun, showing that both of them are below the sphere of the Sun. The research made so far on Ibn Sina’s report shows that it might relate to a really observed Venus transit. Quṭb al-Dīn al-Shīrāzī (d. 1311 AD) in his astronomical books presents a list of some of these reports. But, being under the influence of numerical calculations of Muʾayyid al-Dīn al-ʿUrḍī (d. 1266 AD) on the distances and sizes of the planets, he believes that the sphere of Venus is above the sphere of the Sun. So he argues that it is impossible to observe a Venus transit even if it were below the Sun. Using the Ptolemaic rules of occultation and natural order, he criticizes the standard order of the planets. Finally he argues that what they have observed is nothing but a Sunspot.

All that we know about the life and times of al-Sijzī, the 10th century Iranian Muslim mathematician and astronomer, is limited to the small pieces of information provided by other authors’ accounts and some of his own works. On the basis of al-Sijzī’s mathematical works and the extant maunscripts written in his hand, some modern scholars have estimated his date of birth in about 942 ad. Numerous works of al-Sijzī are extant in three areas: mathematics, astronomy and astrology. Although there is a considerable number of astrological compositions among al-Sijzī’s works, little research has been done about them. One of the most important astrological works of al-Sijzī is al-Jāmiʿal-Shāhī, in which the author mentions some historical and astronomical events of the 10th century. Nevertheless, there exist some other collections of al-Sijzī’s astrological works catalogued under the title “al-Jāmiʿ al-Shāhī” and often mistakenly considered as the same book as al-Jāmiʿ al-Shāhī. In this article we try to provide more accurate information about al-Sijzī’s life and period of activity and to show that these astrological collections are not a single work and are different from al-Jāmiʿ al-Shāhī.

The official Iranian calendar is a solar one that in both the length and the first day of its year is based not on convention, but on two natural (i.e. astronomical) factors: a) the moment of coincidence of the centre of the Sun and the vernal equinox during the Sun’s apparent revolution around the Earth; and b) the time length between two successive apparent passages of the Sun’s center across that point. These factors give this calendar the chance that 1) its beginning is the beginning of natural solar year, 2) its length is the length of solar year, and 3) the length of its months is very close to the time of the Sun’s passage across twelve signs of the Zodiac from Farvardin/Aries to Esfand/Pisces. In this paper it would be shown that a) discussions concerning these facts have their own historical backgrounds, and b) up-todate computations, being based on choosing the tropical year (i.e. 365.24219879 days) as the length of the calendar year, give the best possible intercalation with its specific system of leap years. Thus, on the grounds of historical documents, astronomical data, and mathematical calculations, we establish the Iranian calendar with the highest possible accuracy, which gives it the unique exemplary place among all calendars.

This article exposes an analysis of the Zoroastrian Persian calendar in a 12th century Hebrew book on the Jewish calendar (Sefer ha-‘Ibbūr). The Hebrew treatise was composed by the polymath Abraham bar Ḥiyya, probably in Northern France. Bar Ḥiyya depicts the structure of the Zoroastrian Persian calendar, its months and some of its festivals. He then expounds on calendrical algorithms which enable to convert between Persian and Jewish dates. Although one finds the names of some Persian months and festivals in earlier Jewish sources, Abraham bar Ḥiyya’s text not only elaborates in greater detail on these matters, but for the first time in Hebrew literature, one encounters conversion algorithms between the two calendars.