• Poleni’s geometrical instruments to trace transcendental curves, by Pietro Milici, University of Insubria (Italy)

    Figure 1. Poleni’s machines for the tractrix (left) and the logarithmic curve (right) in the Letter to Hermann.

    During the 17th century, mathematicians radically modified their idea of a curve, transitioning from the trace of a geometrical mechanism to the solution of an equation. With that in mind, Descartes and Leibniz introduced theoretical machines (i.e., sketches to be considered mentally but not practically realized) to legitimate the geometrical status of algebraic and transcendental curves obtained as solutions of analytical equations. In the first half of the 18th century, a few scholars converted some theoretical machines for transcendental curves into material instruments. We focus on the geometric instruments designed by Giovanni Poleni (1683-1761), a polymath and Professor at the University of Padua in Italy. These instruments had been described with an engineer’s precision both in textual and graphical representations (as visible in Figure 1) in a letter to Jacob Hermann who was Poleni’s predecessor in the chair of Mathematics. The letter was included in Poleni’s Epistolarum Mathematicarum Fasciculus of 1729.

    In 1739, Poleni inaugurated a unanimously praised laboratory of experimental physics (“Teatro di Filosofia Sperimentale“) that grew also with his successors. Such a Paduan museum still exists and is dedicated to its founder (today it’s named “Giovanni Poleni museum”). Between the machines present in the collection, Poleni listed the ones for the tractrix and the logarithmic curve: also the modern catalogue (Gian Antonio Salandin & Maria Pancino, Il “teatro” di filosofia sperimentale di Giovanni Poleni, LINT, 1987) confirms that there is a sample of a geometrical machine for our transcendental curves. Thanks to an SIS grant, I got the opportunity to observe, manipulate and film such a machine (see Figure 2).

    Figure 2. The machine of the Giovanni Poleni Museum classified as the one for the tractrix and the logarithmic curve.

    Indeed, differences between the artefact in the collection and the designs of the Letter are visible at the first glance. Furthermore, reading the description in Poleni’s index, the machine also differs in materials. In any case, also because of missing pieces, we have no idea of the purposes of such an artefact.

    To our knowledge, no copy of Poleni’s geometrical machines is available: therefore, together with Frédérique Plantevin (University of Brest, France), we decided to reconstruct the machines meticulously described in the Letter to Hermann. After a 3D digital modelling of the machine, we contacted the artisan Uri Tuchman to realize a working model in the materials described by Poleni. We are still working to complete an informative video and a paper on these topics.

  • The use of astronomical instruments in Colonial Chile, by Virginia Iommi Echeverría, Instituto de Historia, Pontificia Universidad Católica de Valparaíso (Chile)

    The use of astronomical instruments in Chile during the colonial period (1540-1810) remains an obscure subject. Despite a few references in contemporary sources to glasses and armillary spheres, very little is known about the instruments themselves and how they were used. Although the introduction of the printing press in Chile has been dated to near the end of the eighteenth century, the existence of numerous libraries and an active book market by then show the importance of considering bookish astronomy as a fundamental part in this historical task, for not only did books provide theoretical insights into the discipline but also astronomical tables, models and visual instructions for the fabricating instruments. The purpose of this project was to examine these paper instruments as surviving testimonies of astronomical study and practice.

    Figure 1: The second volume of Tabulae Primi Mobilis by Andrea Argoli (1570-1657)

    Thanks to an SIS grant, I was able to examine astronomical books printed between the sixteenth and eighteenth centuries preserved at Biblioteca Nacional de Chile in Santiago. One of the founding collections of this library was the books owned by the Jesuits at the moment of their expulsion from the territories of the Spanish crown in 1767, when their possessions were requisitioned and inventoried in detail. The catalogues of belongings found in churches, houses, missions, and colleges show that the members of the order owned several books on astronomy and mathematics. The largest book collection in eighteenth-century Chile was located at the Colegio de San Miguel in Santiago, where more than 6,000 volumes were preserved. By comparing the titles mentioned in the inventories with the present holdings at the Biblioteca Nacional, it was possible to conclude that most of their astronomical books are now lost. One of the few exceptions is the copy of the second volume of Tabulae Primi Mobilis by Andrea Argoli (1570-1657), which is clearly identified as a possession of the Colegio de San Miguel with a handwritten inscription in the frontispiece (see figure 1).

    Figure 2: Giovanni Paolo Galluci’s Theatro del mundo y del tiempo

    In the inventory, it is described as “Argoli Tabula” (Archivo Nacional de Chile, Fondo Jesuitas, 1767 Vol. 7, fol. 311r). Although not mentioned in the catalogue, a copy of Giovanni Paolo Galluci’s Theatro del mundo y del tiempo contains signs of use that may be helpful for studying astronomical practice in the period (see figure 2). The copy in Biblioteca Nacional belonged to the Jesuit house of San Juan and has numerous handwritten annotations and marks. This research has confirmed that despite the scarcity of sources and objects preserved, a study of astronomical activity in Colonial Chile should give books a central role in the reconstruction of observation, computation and instrument fabrication.

  • 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.

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