Having lost the favour of the Danish court in the latter years of the sixteenth century, Tycho Brahe published his Astronomiae instauratae mechanica<\/i> in 1598 as part of a strategy to procure royal patronage elsewhere. Addressed to his eventual patron, Holy Roman Emperor Rudolph II, the work lavishly described and illustrated the innovative astronomical instruments that Tycho had designed and constructed on the island of Hven, the site of his astronomical programme under the patronage of the Danish court. Though primarily focused on his instruments, the work also included an appendix on 'architectonic structures suitable for astronomical observations', which offered descriptions and illustrations of his two observatory buildings, as well as a map of Hven based on his own observational data. As such, the Mechanica<\/i> offered not simply an overview of Tycho's instruments, but rather a presentation of his whole astronomical programme for which he was seeking financial support. This engraved image depicts Tycho's famous mural quadrant, with which he measured stellar altitudes. The arc itself is divided using transversal points ' diagonal lines drawn between consecutive pairs of divisions to artificially extend the distance between points, allowing greater subdivision of the measuring scale. Though this technique was not invented by Tycho, he is particularly credited for its novel application to astronomical instruments, which thus improved the resolving power of his tools. As a result, Tycho was able to claim precision of up to five seconds using this quadrant. Similarly, this instrument made use of Tycho's innovative sighting devices, which consisted of a series of parallel slits through which celestial phenomena could be aligned, removing potential parallax errors inherent in traditional pinhole sights. Besides presenting the mural quadrant itself, this image also offers an idealised representation of life within Tycho's island observatory. The assistants in the foreground offer a sense of the mural quadrant in use, as well as the collaborative nature of Tycho's observational programme. Alongside the assistants, Tycho Brahe himself is also depicted within the arc of the quadrant, seated at a table in his noble attire. Gesturing both to the aperture in the wall through which observations are made and to the open text on the table before him, Tycho emphasises the important role of both theory and observation to his astronomy. In the background, through the architectural frames, one is presented with a view of the different levels of Tycho's observatory building and the respective activities undertaken therein. The lowest level, in the basement, contains Tycho's alchemical laboratory. Though Tycho is renowned for his celestial observations, this image highlights the importance also of alchemical studies, which he describes as his 'terrestrial astronomy'. Above the laboratory is the library, where his various assistants are seen at work. The great brass globe upon which Tycho recorded stellar positions based on his own observational data is prominently positioned in the centre. Above this, on the top level, are his observational decks, where several of his astronomical instruments can be seen. This image thus gives an indication of the scope of instrumentation available to Tycho; from the mural quadrant in the foreground, to the numerous instruments depicted in the background. The small mechanical globe in a niche above Tycho's head also serves to reinforce the multiple functions of astronomical instruments in this period; they could be simultaneously precision observational tools, demonstration models, and elaborate ornaments. The inscription (RS) at the top of the image reads as follows: Figure of Tycho Brahe, son of Otto, the builder of this building and astronomical instruments. In the year 1587, at the age of 40 years.<\/p>" }, { "label": "Date of Creation", "value": "1602" }, { "label": "Title", "value": "Mural quadrant" }, { "label": "Material", "value": "paper" }, { "label": "Classmark", "value": "M.8.33" }, { "label": "Note(s)", "value": "
An English translation and commentary may be found in Hadravová, Hadrava and Shackelford (1996), pp. 30-5. The following is a summary of Brahe's description based on this translation.Mural or Tychonian quadrant: description and use.This quadrant (BDEC) we made from solid brass, five inches wide and two inches thick, with a radius of nearly 5 cubits [almost 2 metres]. It is so large that each minute can be divided into six portions using transversal points, allowing ten or even five seconds to be easily read [1].The quadrant is firmly fastened to a wall (MPQ) pointing due south, such that the position of the instrument corresponds to the quadrant of the celestial meridian. On a perpendicular wall pointing east'west (LMNB) is a square hole that can be opened or closed using a shutter. In this hole is a gilded brass cylinder; when the sky is clear it is possible to sight along both sides of this cylinder using pinnules near D and E ['pinnule' here refers to the Tychonic sights comprised of a series of parallel slits, rather than to each individual sight]. Indeed, this quadrant has two pinnules, so that the one best-suited to the altitude to be measured may be used. Each pinnule has a square plane one hand broad corresponding exactly to the diameter of the brass cylinder, so that one is able to sight through the parallel slits on all four sides of the pinnule in order to determine altitude and meridian transit at the same time. If, however, only altitude is required, the observer (shown near F) uses the upper and lower slits to sight along the sides of the cylinder, reporting the measured altitude to a collaborator sitting at G, who then records the observation. In order to ensure that the time of observation corresponds exactly with the meridian transit, a third collaborator at H watches the clocks I and K and, upon a signal from the observer at F, the time is recorded by the person sitting at G. The clocks are constructed such that they provide not only single minutes but also seconds with the greatest accuracy; although this is difficult to achieve, it can be attained through great care. It is necessary to have at least two clocks so that if error creeps in, it can be noted and corrected; we have four such clocks.The picture within the circumference of the quadrant is added for the sake of ornament and though not really relevant, will be explained briefly. Below T is a portrait of myself, seated at a table in a long cloak, pointing with one hand towards the cylinder and with the other to the objects on the table, as if indicating to my collaborators what is to be observed and for what purpose. Tobias Gemperlin painted this portrait with such great skill that it could scarcely be a better likeness. Above my head near X is a gilded brass globe, with internal wheels that allow it to revolve and imitate diurnal motion, and also show the course of the Sun and Moon. The phases of the Moon are demonstrated, while the motion of the Sun indicates the hours of the day, the times of sunrise and sunset, and the meridian transits. I invented this ingenious mechanism [automaton] and constructed it at my own expense. In 1590 I humbly presented it to His Majesty Christian [IV], then King Elect, when he visited me at Uraniborg on the island of Hven at the age of 14; this globe is still in his possession. In return, His Majesty presented me with a golden chain adorned with his own portrait. Above this globe, part of my library is represented at V. Two portraits hang in round frames at Y and Z: one represents the late King Frederick II and the other his queen, Sophia, both of whom always graciously supported me and my work. The other paintings in the inner space are: some of my instruments (1-4); below this my study, with tables at 5 and 8 at which my assistants (who numbered six or eight, sometimes ten or twelve, in addition to boys and young students) could sit when making calculations. Behind the pillar in the middle of the study is a large brass globe, six feet in diameter (between 6 and 7). Below, in the underground basement is my chemical laboratory (9-11), which had sixteen alchemical furnaces. I have always been interested in this study, no less than astronomy. My faithful hound (12) is lying at my feet. These painting were composed by three artists each distinguished in their particular field: my portrait was painted by the aforementioned artist from Augsburg; the building and its contents by my architect, Johannes Stenwinckel of Emden; the landscape, mountains and sunset by the royal Kronborg artist, Johannes of Antwerp. Above the composition at RS is an inscription.The quadrant is used for determining the maximum altitudes of the stars [sublimitatibus: sublimitas is here used for the greatest altitude above the horizon reached by a celestial body passing through the meridian]. This may be done to within one-sixth of a minute, by sighting through the upper and lower slits of one of the pinnules along the corresponding sides of the cylinder and reading off the position of the pinnule on the outer rim of the quadrant. The moment of meridian transit can also be found using the double sights and the accurate clocks, as I have described. Astronomers are familiar with the method of using the course of the Sun to find the position of a star from a given altitude, as well as the moment of meridian transit. I used this quadrant to determine the course of the Sun from its altitude in the meridian, allowing the rectangular shadow of the cylinder to fall on the interior space of one of the pinnules, into which the shadow fitted exactly. I have great faith in this quadrant, yet consulted other large quadrants in order to verify my results. [1] Hadravová, Hadrava and Shackelford note that a radius of five cubits (194 cm) would only allow for degree of a length of 34 mm, and for minutes of 0.6 mm. They suggest, therefore, according to Tycho's terms for angular units, that a degree could be divided into tens of minutes (6 mm each), which could be subdivided by transversal points into single minutes.<\/p>
Links to other items:<\/p>
Astronomers, representations of: CUL M.7.36 (Frontispiece weighing up cosmological systems)<\/a><\/p> Astronomers, representations of: CUL L*.9.44(C) (Frontispiece with geographers and astronomers)<\/a><\/p> Astronomers, representations of: CUL M.10.47 (Portrait of Galileo Galilei engraved by Jacob van der Heyden)<\/a><\/p> Astronomers, representations of: Wren T.18.31 (Frontispiece to Hevelius' Selenographia<\/em>)<\/a><\/p> Astronomers, representations of: CUL M.8.10 (Frontispiece to the Rudolphine Tables<\/em>)<\/a><\/p> Astronomers, representations of: CUL L*.9.44(C) (Capital letter with astronomer and armillary sphere)<\/a><\/p> Astronomers, representations of: CUL M.10.47 (Aristotle, Ptolemy and Copernicus with tellurium and armillary sphere)<\/a><\/p> Astronomers, representations of: CUL Syn.8.64.51 (Heliocentric cosmos with Copernicus, Galileo and Kepler)<\/a><\/p> Astronomers, representations of: CUL Inc.5.B.3.96c[1702] (Personification of Astronomy)<\/a><\/p> Astronomers, representations of: CUL Norton.b.14 (Personification of Astronomy, with large armillary sphere)<\/a><\/p> Astronomers, representations of: CUL Syn.6.51.5 (Personification of Astronomy)<\/a><\/p> Astronomers, representations of: CUL Norton.c.32 (Personification of Astronomy)<\/a><\/p> Astronomers, representations of: CUL T*.4.18(D) (Frontispiece of Galileo's Dialogo<\/em>)<\/a><\/p> Further image from this work: CUL M.8.33 (Quadrant)<\/a><\/p> Further image from this work: CUL M.8.33 (Astronomical sextant)<\/a><\/p>