• An “Optical” Bench for the study of Electromagnetic Waves, by Francesca Damiani, University of Bologna

    The discovery of electromagnetic waves, made in 1886 by Friederich Hertz, led the German physicist to deduce that the nature of these waves was the same as that of light waves. More detailed experiments were performed by Augusto Righi, founder of the Institute of Physics of Bologna. Righi’s purpose was to replicate the optics experiments to verify the properties of electrical oscillations, such as reflection, refraction, diffraction and polarization.

    Figure 1: The bench for electromagnetic waves kept in the Museum of the University of Bologna

    To do this, he developed the three-sparks oscillator, in order to generate oscillations of controlled wavelength.

    Figure 2: A sulphur prism that can be mounted on the bench

    Based on the same scheme of an optical bench, Righi developed the bench for electromagnetic waves: the three-spark oscillator was used as a generator, and a piece of silvered glass with a thin groove as a detector. In the central disk, it was possible to place different obstacles, such as prisms and lenses of sulphur, metal mirrors, gypsum and selenite crystals, on which the waves engraved.

    Each piece of the optical bench can be replaced, in order to study waves of different wavelengths. The detector is mounted on a wooden arm that can rotate around the central disk, on which, thanks to a graduated scale, you can read the angle of rotation, to identify the position of maxima and minima, observed by the appearance and disappearance of sparks in the engraving on the glass.

    Details about the instrument and the experiments are described in Righi’s 1897 book The Optics of Electric Oscillations.

    Figure 3: The Holtz machine, an electric current generator used to charge the oscillators

    In my research, that will be submitted in the Bulletin, I studied Righi’s handouts and books, and examined the instrument with its accessories that are preserved at the Museum of the History of Physics at the University of Bologna, and other original detectors and oscillators kept at the Museum of the History of Physics in Padua.

  • Paper Instruments in the History of Ottoman Astronomy, by Gaye Danışan

    This project was born from an idea that several specimens of Ottoman astronomical calendars could also be a subject of paper instrument research. Therefore, the primary purpose was to provide an overview of paper instruments in Ottoman astronomy, a neglected topic up to date. Thus, the study first focuses on identifying Ottoman paper instruments without period limitation, then the classification and analysis based on their variety, usages and periods.

    At the beginning of the research, we started with following three specimens: An Ottoman volvelle found in Rûznâme-i Şeyh Vefâʾ [replicated in 1676, BnF supplément turc 537]; an annual calendar drawn on cardboard by Derviş Mehmed el-Hasib el-Mevlevi [Kandilli Observatory and Earthquake Research Institute, MS 540, copied 1134 H. (1721-22 CE); hereafter KOERI], a quartier de reduction (sinical quadrant) used among French mariners with the name of serko haritası in an Ottoman book on navigation entitled Navigasyon (1857). Some details for these specimens were given in a previous blog. Now, other specimens have also been included in the project.

    The first example is a gurrenâme in circular form with moving part which allows one to find the day of the week corresponding to the beginning of each lunar months for the year 1096 H. [(1685 CE); Gurrenameler mecmu‘ası, KOERI, MS 116, fol. 8v.]. We can understand how to use this gurrenâme from explanations above and below the circle. The second example is another volvelle related to the week’s day corresponding to each lunar months. However, it is uncompleted, or it has some missing parts. This volvelle is found in a perpetual calendar whose precise date is unknown, but it includes a gurrenâme in tabular form, covering the years from 1073-1085 H. [(1662-1674 CE); Gurrenâme, Bursa Inebey Manuscript Library, Orhan Collection, MS OR2084/2, fol. 62r.]. Thus it may be inferred that it is an example of 17th-century calendars. The third example is a volvelle to convert the Arabic, Persian and Coptic calendars (Fig. 1). It is found in a manuscript on preparing a calendar, which is anonymous, and unknown date [Risala fi istihraç at-tavarih, KOERI, MS 180/12, folio 82r.]. The fourth specimen is a circular form without moving part to determine the time of sâlat el-‘îd (Prayer of the eid) corresponding to the year 1251 H. (1835/36 CE). It was found from the digital catalogue in a manuscript about a legend entitled Menakıb-ı Şeyh Ebü’l Vefa which was prepared in 1293 H. [(1876 CE); Suna ve İnan Kıraç Foundation Manuscript Collectşon, MS SR000315, fols. 53v-54r]. The paper instrument is not attached to it. Besides, the different dates between paper instrument and manuscript made us think whether this calendar is a part of the manuscript. Unfortunately, now, the paper instrument is not in this manuscript. It could have been put in a different manuscript, or it could have been lost.

    Figure 1: Image of volvelle to convert the Arabic, Persian and Coptic calendars. (Risala fi istihraç at-tavarih, Kandilli Observatory and Earthquake Research Institute, MS 180/12, folio 82r).

    Another example is especially interesting because it reminds of gunner’s rule, which Bombardiers (Humbaracı) used to measure artillery piece elevation. It was called by the following terms: mizan-ı humbara, alet-i irtifa, humbara terazisi, kantar terazi or just terazi . However, this paper instrument is found in a corpus of treatises on lunar mansions, calendar conversion tables, perpetual calendar and ahkâm text which was prepared by Ahmed Lütfullah el-Mevlevi who was a müneccimbaşı (chief astronomer) between 1660 and 1668 (Süleymaniye Library, MS 1027/1, fol. 63v). The paper instrument is not attached to this corpus, and the precise date of the paper instrument is unknown. Besides, its structure and small size do not allow one to use it for military purposes. Thus it might have been designed for educational purposes.

    The last surviving example is a celestial map entitled Miratü’s-semâ (the mirror of the sky) (Fig. 2, KOERI, No. 223). On the celestial map, there is a note that Tahsin prepared the visibility of celestial sphere for the most of Ottoman lands. We know that Hoca Tahsin Efendi (Hasan Tahsin, d.1881), one of the most prominent scholars of the Ottoman Empire of the 19th century, prepared a celestial map since Bursalı Mehmed Tahir (d.1925) mentioned him in his book entitled Osmanlı Müellifleri[1]. The note on the celestial map also matches up with the passage on Hoca Tahsin Efendi in the Bursalı Mehmed Tahir’s book. Thus, the name of Tahsin may point out Hoca Tahsin Efendi.

    Figure 2: Miratü’s-semâ (the mirror of the sky), (Kandilli Observatory and Earthquake Research Institute, No. 223).

    On the other hand, during this research, we encountered circular diagrams related to calendars onAhmed b. Süleyman et-Tancî’s portolan (1416), Mürsiyeli İbrahim’s portolan (1461) and el-Hacc Ebu’l Hasan’s portolan (1552?), and some manuscripts especially discussing on perpetual calendars. I did not count them in the scope of the project because these examples are controversial in terms of whether the contents of a circular drawing related to calendar systems will be evaluated in the category of paper instruments. However, I think over these diagrams because of their similar context with volvelles related to calenders. Besides, few examples mounted on wood such as Hoca Tahsin’s portable sundial made in Paris in 1867 are not included in the project. 

    The method and results of the project will be shared with full detail in a subsequent issue of the Bulletin. I hope this project would shed light on paper instruments in the history of Ottoman astronomy.

    [1] Bursalı Mehmed Tahir Efendi, Osmanlı Müellifleri, edited by A. Fikri Yavuz, İsmail Özen, Meral yayınevi (İstanbul, 1972), Vol. I, pp. 346–347.

  • Martín Altman, clockmaker and engineer to the Habsburgs, by Víctor Pérez Álvarez

    Born in Silesia in 1530, son of a clockmaker, Martin Altman left his father’s home aged 16 to fight in the Schmalkaldik wars of Emperor Charles V against the Lutherans. After living in different cities for short periods he ended up in Augsburg, a hive of artisanal activity and one of the most important clockmaking centres in Europe. We don’t know whether he moved to Augsburg by chance or driven by his interest in learning horology in the best possible place, but that move determined his future. After the 1555 Imperial Diet (the legislative body of the Holy Roman Empire) he was appointed by the Emperor Charles V and moved to Brussels to join his court, where he spent a few years. During that period he visited England briefly, probably with King Philip II of Spain, then married to Queen Mary Tudor. After the queen’s death in November 1558, Philip II moved back to Spain with his court (including Martin Altman), settling in Toledo.

    A clock that may be attributable to Martin Altman. H. M. VEHMEYER: Clocks, their origin and development. 1320-1880. Vol. I, Gent, Snoeck, 2004, p. 782. Photo credit: Henk Stam

    As Michael Palin would say: ‘Nobody expects the Spanish Inquisition!’ Neither did Altman, who was suddenly arrested and charged with Lutheranism only one year after arriving in Spain. He was released without charge on that occasion, but was arrested again a few years later and his hand was injured in a torture session. Altman survived, but this was a turning point in his life. He started to suffer economic difficulties and needed to borrow money to pay his living costs on several occasions. In addition to this, the king owed him a huge amount of money. By the end of the 1580s, Altman’s situation was unsustainable and in 1591 he decided to sell his workshop in Madrid and, following an offer from the Venetian ambassador, travelled to Italy.

    Altman was a clockmaker: he made, serviced and traded clocks, watches and other instruments. He was in charge of the clocks and scientific instruments collections of Philip II, and had access to the private rooms of the King. He was also an engineer and presented various different inventions to the king, including a diving suit to recover valuables from shipwrecks and different types of bullets.

    Altman, barely known until recent years, is a good example of a Renaissance clockmaker-engineer who dealt with some of the most influential people of his time.

  • Rethinking the Spherical Astrolabe

    SIS Grant Holder Taha Yasin Arslan (Istanbul Medeniyet University, Turkey), explains how his funding helped him discover more about this unusual instrument from the Islamic world.

    Spherical Astrolabe, by Mūsā, Eastern Islamic, 1480/81, MHS Oxford, inv. no. 49687.

    The spherical astrolabe is one of the most mysterious astronomical instruments in the history of instrumentation. Until a fully functional one surfaced in an auction in 1962 and was acquired by the History of Science Museum, University of Oxford (HSM), the reality of this type of instrument as a practical device was uncertain. Its use was only known through descriptions in historical texts. Although parts of another spherical astrolabe are now known to exist, the HSM version is complete and remains unique.

    About 8 cm in diameter, this instrument was dated 885 Hijra (1480/81 CE) by an instrument maker simply signed as ‘Mūsā’. Spherical astrolabes are universal in nature and can be used at any latitude but the unequal hour markings below the horizon on the mater indicate that this instrument was made to be used around 41-degrees latitude, which usually corresponds with Istanbul. Coincidentally, there is an unsigned treatise on the use of spherical astrolabes that was copied in either Istanbul or Edirne around the 1450s or 1460s that is preserved in the Suleymaniye Library’s Hamidiye Collection (no. 1453). The goal of my research was to provide tangible evidence, if possible, between the Hamidiye text and the HSM instrument. I began my journey by examining the Hamidiye text and took notes about the detailed descriptions of the instrument. I then visited HSM for examination of the instrument. With the help of Dr. Stephen Johnston, head of research, teaching, and collections at HSM, I had the chance to thoroughly examine the spherical astrolabe and to compare my notes on both the written and physical instruments.

    From this research, I can confidently say that the HSM astrolabe was made with only artistic intentions, most likely as a demonstration tool to show what a spherical astrolabe looks like and how it operates. The small size of the instrument, the choice of not-so-bright stars to form a symmetry on the rete, and lack of an alidade that can be used for stars makes the instrument visually appealing but impractical for observations. The instrument that is described in the Hamidiye text, however, is much more accurate and functional for both observations and calculations. It is hard to imagine that the author of this text constructed or commissioned a much less accurate instrument such as the HSM astrolabe. I will conclude my research by examining some small details in the text on the use of the instrument to further define if there are some similarities and/or connections between the text and instrument.

  • Paper Instruments in the History of Ottoman Astronomy

    Gaye Danişan Polat from the Department of the History of Science, Istanbul University provides us with an overview of her research which has been funded by a grant from the SIS. Full details to follow in a subsequent issue of the Bulletin.

    The importance of using paper instruments during the Ottoman period remains unexplained because there are few surving examples to help us understand their role in the history of Ottoman astronomy. To date there are still several important questions that need to be answered: When were paper instruments first used by Ottoman astronomers? Which style of paper instruments were used? Who used them? Were they widely used across the Ottoman world? Were the paper instruments used for education or actual calculations?

    This study aims to clarify the purpose of using paper instruments in the Ottoman world by assessing the following surviving examples in the astronomical literature: the first example is a calendar with the title of Ruzname-i Şeyh Vefa (replicated by Ibrahim Shahidi ibn Khoudaï Dede in 1676, BnF supplément turc 537). It includes a paper instrument with two moving circles (volvelles) representing the positions of the Sun and Moon (folio 6). Composed of a series of concentric circles, this instrument enabled the user to perform calculations relating to the age and phase of the Moon, lunar mansions and eclipses (both solar and lunar). The second example (Fig. 1, below) is also a calendar in the Kandilli Observatory (MS 540, copied A.H.1134/1721-22 A.D) made of cardboard by Derviş Mehmed el-Hasib el-Mevlevi (d.1709) who was a muwaqqit (timekeeper). There is a gurrename on the top right corner, and also circles & semicircles featuring the names of planets, zodiac signs, fixed stars, and information about the climates, zodiac, and winds.

    Fig. 1: Derviş Mehmed el-Hasib el-Mevlevi, Takvim, Kandilli Observatory, MS 540, 1 folio, copied in hijri 1134.
    Fig. 2: serko haritası, from: Navigasyon, compiled by Halil Efendi, Mekteb-i Bahriye-i Hazreti Şahane Tabanesi, 19 Ocak 1857, plate 8.

    The third example (Fig. 2) is an Ottoman book on navigation entitled Navigasyon (1857) which features a serko haritası which is equivalent to a quartier de reduction (sinical quadrant) used among French mariners. We can assume that this printed paper instrument was used for pedagogical purposes since the Navigasyon was written for students at the Naval School (Mekteb-i Bahriye). Finally, there are also a few examples mounted on wood that can be to use as surviving instrument like cylindrical sundial, qıblanuma, quadrant. This project will contribute to our understanding of the use and role of paper instruments within the history of Ottoman astronomy.

    Note: For more detailed information about serko haritası in the Ottoman Empire see: Danışan Polat G., “Osmanlı Denizcileri ve Serko Haritası (Quartier de réduction)”, in: Osmanlı Bilimi Araştırmaları/Studies in Ottoman Science, XVIII/1 (2016), pp. 1-25.

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