The Tools of the Trade: An Astronomer's Notebook

Over the past couple of years, I have been studying medieval and Renaissance astronomy and other sciences. My objective is to use period texts and period tools to increase my understanding of the early Renaissance way of relating to the world. My “viewpoint character” is Palmerin da Castello, a scholar at the University of Bologna in the late fifteenth century. Bologna at that time had a professor of astrology, and Palmerin is studying under him. Grendler (2002) describes the education at Renaissance universities in Italy, and even lists the texts that would have been taught, including Euclid's Elements, the Almagest of Ptolemy, and Sacrobosco's De sphaera. I have been reading those that are available in English translation, and working to understand both the science and the accompanying worldview.

Period texts are one way of relating to the world; period and reproduction items are another. The notebook is one common tool of the scholar. Rather than a showpiece, or art calligraphy, this notebook is a working item. In some ways, the materials and methods of production are more important to me than the final result. Everything is as correct to the period as I could make it, from the quill pen and ink to the paper and parchment, and the choice of contents and writing style. There are plenty of mistakes and messy writing, but that is true of scholar's working notebooks from the dawn of writing until the modern day. I will continue to use this functional tool to record astronomical and astrological data and observations.

The outside of the book showing the parchment binding and the toggle.

The book open to tables for August and September.

The Book

This project was inspired by two fifteenth century notebooks of the Schoenberg Center for Electronic Text and Image at the University of Pennsylvania. The first is a fifteenth century northern Italian herbal (Unknown, 1400s, MS LJS419 Schoenberg Center for Electronic Text and Image), and the second is an Austrian alchemist's notebook by Georg Hayniger from 1467 (MS LJS382 Schoenberg Center for Electronic Text and Image). The latter especially shaped my vision for this project as something that was used and can continue to be used. The Italian herbal is by no means a showpiece, but was somewhat more formal. This book was probably worked on over a period of years to decades, and by more than one contributor.

The book was assembled using a limp vellum binding, very characteristic of notebooks and ledgers of the medieval period, and particularly of northern Italy (Szirmai, 1999). This binding was used for the Italian herbal mentioned above. When planning my project, I looked at examples illustrated in Szirmai (1999), and the Spanish bindings pictured online in great detail by Robertson (2004). My objective was to make a book that was characteristic of the period, without being an exact copy. The originals I looked at were frequently assembled with alum-tawed thongs. Alum-tawing was a method of treating animal hides by soaking them in alum and salt. It produced soft and flexible thongs, and was often used for bookbindings because its white, porous surface took dye well. Alum-tawing does not produce true leather, and the product is not stable in wet conditions, but this wasn't a drawback for book production. Alum-tawed thongs are nearly unobtainable today, so I used waxed linen for the sewing-in of the quires and as tackets on the parchment binding. The sewing pattern follows the archival stitch described by Szirmai (1999). The size of this book was determined by the paper, parchment, and intended contents, but fits into the width and height ranges and proportions of surviving volumes. Parchment toggles were often used on bindings of this type. The cord is a fingerloop braid in linen.

The Paper & Parchment

Authenticity of materials was very important to me, but I was interested in materials that would have been affordable by a scholar, not the high-quality materials available to the wealthy. What would have been ordinary paper in the fifteenth century is now hard to find and expensive. The paper in this notebook was produced by the Saint-Armand paper mill in Canada. I purchased samples of two papers. One was 100% linen rag but machine made; the other was handmade with four deckle edges, but made of a mixture of cotton and linen (still 100% rag). I recently had the opportunity to handle a seventeenth century piece of paper, and the handmade paper was much closer in feel and appearance to that nearly-period example, even though it wasn't 100% linen as I had wished. The notebook probably would have been purchased from a stationer, but would have been a lower-end item. I chose to represent that by leaving the deckle edges where possible, because it would have been extra work for the stationer to remove them.

The parchment cover of the book has been recycled from a nineteenth century English legal document (photographed and recorded). Scraping off parchment for reused (called a palimpsest) was an extremely common medieval practice. There are medieval books with parchment covers where the original parchment document is still legible. I liked the effect, so I was careful to scrape off the printed writing with pumice, but left some of the hand-inked lines and writing.

The Ink

Black gallotannate inks are characteristic of medieval manuscripts. Most are made with oak galls, but other tannin sources can be used. All require an iron source of some kind, and gum arabic was commonly used to improve the writing properties of the ink. I read a wide variety of medieval and Renaissance (and a few later) recipes for black ink: from the Tollemache Housebook (Griffiths, 2001); Theophilus' On Diverse Arts (1979 edition); and collected online by Eusman and Lindquist). Theophilus recommends hawthorn bark, but the rest use oak galls as the tannin source. Green vitriol (ferrous sulfate) was the most common iron source.

Like most medieval recipes for anything, these seem to be as much taste, personal preference, and tradition as true quantitative directions. Most recipes seem to be 2:1 or 3:2 oak galls:vitriol by weight, but the ratio was as high as 5:1. I used a 3:1 ratio of Mediterranean oak galls to green vitriol. Although it probably won't matter in my lifetime, using a higher proportion of ferrous sulfate may increase the corrosive properties of the ink. For most of the recipes, the galls are broken up (but not too fine) and mixed with the vitriol, followed some period of soaking or simmering. Recipes varied from 10 days of soaking with no simmering, to several hours of simmering with no soaking. I chose the latter approach (instant gratification, or more nearly so). I started with enough distilled water to cover the galls and vitriol, and continued to add more as the ink simmered away. It turned black very quickly, but I continued to simmer it for about an hour to extract more of the gallotannic acid from the galls. After I decided that was long enough, I strained the galls and sludge from the bottom. I put more water in with the sludge and left it to sit, making a second batch of ink. In proper medieval fashion, I dissolved in powdered gum arabic until I liked the consistency and flow of the ink.

The Pens

I used only quill pens to write in this book. I used information on how to cut quills from Johnston (1977) and from a web page by Li. I used both purchased (craft store) and “wild-caught” feathers found lying on the ground. It took some practice to get good quills, especially for fine writing as in the tables. I also learned that it is much harder to cut a quill that works well on rough handmade paper than one that works well on smooth modern office paper. The inconsistencies in width throughout the book and the split lines seen occasionally are both due to variations in the quill. The splits seem to be a matter of experience, but the nib widths varied someone in medieval documents, especially ones of this type intended to be used over long time periods.

The Contents

This is a notebook to be used by a practicing astrology student, so it contains information of various useful types. The main component is a calendar with much useful information.

The Hand

The writing is patterned after a fifteenth century Italian herbal (Figure 1). This book, as well as the alchemist's notebook in Figure 2, inspired the “look” that I wanted – a working record, not a showpiece, messy, inconsistent, and full of errors. The herbal is from the appropriate time and place, so I used the letter-shapes from that document. My objective was to spend enough time writing this hand that it felt natural, even with a quill pen, but I didn't quite achieve that “zen”. In particular, I occasionally made mistakes with the letter “l” that were not characteristic of the overall variability within this herbal.

The herbal didn't have any examples of numbers, so I took the shapes for those and for astronomical symbols from Richard Trewythian's ephemeris for 1450 (Page, 2002)). The date is correct, but the ephemeris is English rather than Italian. I would like to find a northern Italian equivalent, but haven't located one. It took me some time to get used to the shape of the 5, and there are examples throughout where I gave it a tail like a modern 4. I very much like the 3, 4 and 7, though.


The calendar is loosely patterned after that of Nicholas of Lynn, an English example from the preceding century. The information therein is commonly found in medieval calendars, but that was the best-explained example I have located (see also Evans, 1998). The Latin names of the months come from this calendar.

Metonic Cycle

The column with the Roman numerals shows the date of the new moon for each year in the 19-year Metonic cycle (Evans, 1998). Nicholas of Lynn's calendar also included this information. This cycle spans 1995-2013. In the first year of the cycle, new moons fall on the days indicated by i; in the second year by ii; and in the twelfth year by xii (and so on). The dates are calculated by identifying the date of the first new moon in each year (note that in the first year of the cycle it is on January 1), and then adding alternate 30-day and 29-day lunar months, then superimposing this on the calendar months. (Which is what I did, starting only from almanac data for January of each year.)

Domenical Letters

Domenical letters are a seven-day cycle, a-g and starting over. In a multiyear calendar such as this, if you know the date of the first Sunday, every Sunday in the year will have that same domenical letter. These are also called Sunday letters. Nicholas of Lynn also included these; in conjunction with the Metonic cycle information, they can be used to calculate the date of Easter.

Location of the Sun

“locus solis”, the true and accurate location of the sun within the zodiac, is based on 2006 data from the NASA Jet Propulsion Lab HORIZONS System. The sun moves at different speeds through the zodiac at different seasons, so simple arithmetic is not enough to calculate the location, and tables were commonly used. Nicholas of Lynn shows one appropriate to his time. The

Length of the Day

“quant diei”, the final column, is the length of the day on each date, calibrated for the latitude of the Shire of Nithgaard (State College, PA). This was calculated using Ptolemaic methods as explained by Evans (1998). Among other things, this information is useful for converting between local seasonal hours (12 per day and 12 per night) to local equal hours (24 per day). Correct timetelling is necessary for constructing horoscopes. There is space after this column for notes, information on eclipses, or marginalia.

Other Information

There is plenty of space left in the notebook for more information, as it becomes needed. There is now a table of latitudes of the Baronies of AEthelmearc. I will probably include a table with more horoscopic information, and more things as they occur to me.


I found it very satisfying to use a notebook made entirely from the appropriate materials with a quill pen and oak gall ink to record astronomical information calculated using Ptolemaic trigonometric methods. (And I love watching the ink darken over time!) This may be as close as I can come to the experience of being a medieval scholar, and I tried to shut off my modern brain and think from a fifteenth-century perspective while I worked on this project. Of course I didn't entirely succeed, but the effort was rewarding and educational. I also would like to encourage more people to produce things that are to be used, not solely art pieces. While I would never, ever disparage the efforts of our scribes, or the amazing results they produce, I think we may have lost sight of the everyday uses of writing, the sloppy notebooks and lists, that medieval scholars would have used every day.


Eusman, Elmer. The ink corrosion website. (Accessed Dec. 2006.)

Evans, James. 1998. History and Practice of Ancient Astronomy. Oxford University Press.

Grendler, Paul F. 2002. The Universities of the Italian Renaissance. Johns Hopkins University Press.

Griffiths, Jeremy. 2001. The Tollemache Book of Secrets: A descriptive index and complete facsimile with an introduction and transcription together with Catherine Tollemache's Receipts of pastry, confectionary, etc. The Roxburghe Club, London.

Hayniger, Georg. 1467 Autograph Alchemical Compendium of Recipes and Drawings. MS LJS382. Schoenberg Center for Electronic Text and Image. (Accessed March 2007.)

Johnston, Edward. 1977. Writing, Illuminating and Lettering. Pitman Publishing.

Li, Liralen. Cutting quill pens from feathers. (Accessed Dec. 2006.)

Lindquist, Evan. How to make permanent gallotannate ink. (Accessed Dec. 2006.)

Nicholas of Lynn. 1980. The Kalendarium of Nicholas of Lynn. (ed. S. Eisner). University of Georgia Press.

Page, Sophie. 2002. Astrology in Medieval Manuscripts. University of Toronto Press.

Robertson, Holly. 2004. Spanish Archival Bindings 1300 – 1800. (Accessed March 2007.)

Szirmai, J. A. 1999. The Archaeology of Medieval Bookbinding. Ashgate Publishing.

Theophilus. 1979. On Diverse Arts. (eds. Hawthorne, J.G. and Smith, C.S.). Dover Publications.

Thorndike, Lynn. 1949. The Sphere of Sacrobosco and its Commentators.University of Chicago Press.

Unknown. 1400s. Herbal containing 192 drawings of plants. MS LJS419. Schoenberg Center for Electronic Text and Image. (Accessed March 2007.)