Wednesday, August 28, 2013

A leech’s work for August

Even today, the work of physicians and other medical practitioners varies somewhat from month to month. In the United States, many foodborne infections peak during the summer months:

Many foodborne infections are most common during the summer, as shown by the examples of Salmonella, Campylobacter, and Vibrio in the figures above. The graphs are from CDC. Foodborne Diseases Active Surveillance Network (FoodNet): FoodNet Surveillance Report for 2010 (Final Report). Atlanta, Georgia: U.S. Department of Health and Human Services, CDC. 2011. Accessed at  on August 27, 2013.

 Many airborne allergens are also seasonal. For example, in central Texas cedar pollen is found primarily during the winter months:

Weekly totals of the daily cedar pollen counts (in grams per cubic meter) from channel KVUE in Austin, Texas. The television station takes daily pollen counts outside its studios. The data shown in this graph illustrate the period from August 5, 2012 (the start of epidemiological week 32 of2012) until August 3, 2013 (the end of epidemiological week 31 of 2013). The peak occurred during week 4 of 2013, which was from Sunday, January 20, until Saturday, January 26, 2013; this week is labeled as 13-04 on the graph above. The cedar pollen data were obtained from on August 8, 2013 and the daily counts were used to generate weekly totals, with the epidemiological weeks numbered as described at

 While modern medical practitioners can expect some variation from month to month in terms of which conditions are more common, access to medications does not generally vary much from season to season. Influenza vaccines may only be available before and during the influenza season, but otherwise most medicines can be obtained at any time of the year. However, in Anglo-Saxon times most medications were based on plants, and not all plants were available throughout the year. Different plants could be harvested during the different months of the year. Some plants could be dried for use over an extended period of time, though fresh and dried herbs may differ in effectiveness.

In the old Anglo-Saxon calendar, the lunar month roughly corresponding to August was known as Weodmonath, or the month of tares (weeds), because it is a peak time for weeds and other plants. August was apparently a peak time for harvesting medicinal herbs as well, based on evidence from the harvesting suggestions contained in the Old English Herbarium. This Old English medical text mostly consists of a translation of the Herbarium of Pseudo-Apuleius, a Latin text originally written as early as the fourth century. The Old English Herbarium survives in four Anglo-Saxon manuscripts. August was the most commonly mentioned month recommended for harvesting the medicinal herbs included in the text, being listed as the optimal month for six herbs: wood betony (Stachys officinalis), cinquefoil (Potentilla reptans), sweet flag (Acorus calamus), wall germander (Teucrium chamaedris), aster (Aster amellus), and melilot (Melilotus officinalis). I generated this list of August herbs by searching the online text of the Cockayne translation of the Old English Herbarium as well as printed versions of two more modern translations by Anne Van Arsdall (Medieval Herbal Remedies: The Old English Herbarium and Anglo-Saxon Medicine) and Stephen Pollington (Leechcraft: Early English Charms, Plant Lore, and Healing). The modern English and scientific plant names listed above are from The Old English Illustrated Pharmacopoeia by M. A. d’Aronco and M. L. Cameron. Future blog postings will explore these August herbs in more detail.

Even today August is considered a good month for collecting herbs in temperate zones. Near the beginning of the month I received a gardening newsletter by email, reminding me that this would be an optimal time to harvest many culinary and medicinal herbs for peak potency. So when you snip your herbs this month, you are taking part in a tradition going back hundreds of years. August would have been a busy month for Anglo-Saxon leeches (healers) as they collected medicinal herbs to last over the coming months.

Tuesday, August 27, 2013

The Anglo-Saxon calendar

Herbs and other plants are the major theme for this blog, which means that we must also consider the seasons and the calendar. Some plants only grow well at certain times of the year, so gardeners and farmers develop planting schedules that show the best calendar dates for planting seeds or transplants. In my part of Texas I think that timing is the factor most responsible for tomato production in my garden. If I plant at the right time, I have a good chance of getting plenty of tomatoes for sauce and fresh eating. If I plant too early in the spring, the tender young tomato plants may suffer freeze damage and die. If I plant too late in the spring, by the time the tomatoes start to produce flowers it may be too hot for them to set fruit. Planting schedules are widely available from county extension offices to show optimal planting dates for local regions.

Abundant tomato harvest from USDA zone 8, Texas, June 14, 2013. The young tomato plants were planted in early March and protected from early frosts. Picture by Wyrt Wizard.

In the agricultural society of Anglo-Saxon England, farmers would need some means of keeping track of times for activities such as planting and harvesting. The Venerable Bede provided the best overview of the Anglo-Saxon calendar in his work De temporum ratione (725 AD), which Faith Wallis translated into modern English  (On the reckoning of time, 1999). Bede listed the names of the Anglo-Saxon months along with their approximate Julian-calendar equivalents. His explanation of the month names also yields insight into pagan Anglo-Saxon practices. There are two months called Giuli (December and January) and two months called Litha (June and July); the solstices occur during these double months. The double months may have been been further described with Ærra and Æftera to indicate the earlier and second months by that name.

Anglo-Saxon month name, as transcribed by Wallis (as listed by Bosworth and Toller in parentheses
Approximate Julian month
Meaning of Old English month name (according to Bede’s account)
Giuli (Geóla; Æftera Geóla)
Reference to the winter solstice, when the sun turns back and begins to increase
Solmonath (Solmónaþ)
Month of cakes, which were offered to the gods
Hrethmonath (Hréðmónaþ)
In honor of goddess Hretha, to whom sacrifices were offered this month
In honor of goddess Eostre, for whom feasts were celebrated
Thrimilchi (þrimilce)
Three milkings, because the fertile area allowed cattle to be milked three times a day this month
Litha (Líða; Ærra Líða)
A reference to the gentle breezes suitable for sailing
Litha (Líða; Æftera Líða)
(see above)
Weodmonath (Weódmónaþ)
Month of tares, because weeds were plentiful at this time
Halegmonath (Háligmónaþ)
Month of sacred rites
Winterfilleth (Winterfylleþ)
Winter-full, because the winter season began at the full moon this month when the year was divided into only two seasons (summer and winter)
Blodmonath (Blótmónaþ)
Month of immolations, when cattle were consecrated to the gods and then slaughtered
Giuli (Geóla; Ærra Geóla)
(see above)
Anglo-Saxon months are believed to have started on the evening when the first crescent moon was sighted, which generally occurs one or two days after the astronomical new moon but can take three days in some cases.

August 6, 2013
August 7, 2013
August 8, 2013
August 9, 2013. These pictures from the United States Naval Observatory (USNO) show simulated moon images at 20:00 UT on the August 2013 astronomical new moon date (August 6; top picture) plus the next three nights. The new crescent moon could not be seen until August 9, 2013 (bottom picture).

If we want to reconstruct the Anglo-Saxon calendar for modern or historical times, we need to know the dates of first crescent moon sightings. Tables of astronomical new moon dates and times are widely available for the present day and even for ancient times as far back as 2000 BC, but it is more complicated to estimate the date of first crescent visibility. The time between astronomical new moon and first crescent visibility depends on many factors, including the observer’s location on Earth. For the new moon of 6 August 2013, an observer in most of the United States could first spot the new crescent on 8 August while an observer in the United Kingdom could not be expected to catch a glimpse of the crescent moon until 9 August.

August 6, 2013
August 7, 2013
August 8, 2013.
These illustrations of the visibility of the new crescent moon following the new moon of 6 August 2013 were obtained through the Websurf portal of Her Majesty's Nautical Almanac Office (HMNAO), at the next new moon page. The red colored area shows where the crescent moon was expected to be easily visible without optical aids. On 6 August 2013 (top picture) the crescent moon would not have been visible anywhere on Earth. On 7 August 2013 (middle picture) the crescent moon was expected to be easily visible only in southern parts of South America. On 8 August 2013 (bottom picture) the crescent moon was expected to be easily visible across much of the planet including most of the United States, but on this date the crescent moon was not yet visible from the United Kingdom.
© Crown Copyright  2013. Contains material generated by Her Majesty's Nautical Almanac Office (HMNAO) and reproduced by permission of the United Kingdom Hydrographic Office (UKHO) and Her Majesty's Stationery Office (HMSO)

The Websurf portal of Her Majesty's Nautical Almanac Office (HMNAO) has a calculator which will estimate the date and approximate time of first crescent visibility for any given location on Earth. For more ancient historical times I could not find a comparable calculator to provide tables of first crescent sightings, but the Sky View Café will display simulated lunar images for times going back before Christ and for any specified location on Earth, allowing the user to scan the daily images by month and visually estimate when the crescent first became visible. With these tools, it is possible to estimate the starting dates of the Anglo-Saxon months for historical, present, and future times.

Bede indicates that the months were lunar and the years were solar. Intercalary months were inserted into the summers of some years to keep the lunar months reasonably in sync with the solar year, in the same way that we add an extra day (leap day) to some years. Unfortunately, Bede did not indicate how it was known when to insert an intercalary month, or a third Litha month. The timing of intercalary months may have been determined by observation of astronomical events or by following a set cycle such as an eight-year or 19-year cycle during which years with intercalary months (embolismic years, or “swollen” years; symbolized by E) would occur at specific times relative to ordinary (O) years: for example, OOEOOEOE in an eight-year cycle. Lance Latham suggests that an eight-year cycle would be simple to follow and accurate over long periods of time. Wooden rune staves, which would not be expected to survive intact into the present day, could have been used to keep track of the years. (Latham’s work was posted at  as of July 9, 2012, but Latham died in 2008 and his SUNY-Albany site is no longer active. I have posted his paper here.)  Swain Wodening reconstructs the Anglo-Saxon calendar in modern times by following a 19-year Metonic cycle: OOE OOEOOEOE OOEOOEOE.

Although it is certainly plausible that Anglo-Saxons followed eight-year or 19-year cycles, it is also possible that they used rules based on astronomical observations to determine when intercalary months should be inserted. John Robert Stone suggests three possible rules based on examining the timing of the first sightings of the new crescent moon around the winter solstice and/or the summer solstice.

Rule #1: The next month is intercalary if the first crescent of the after Litha is observed on or before July 4, the eleventh evening after Midsummer Eve (June 23).

Rule #2: The next month is intercalary if the first crescent of the after Litha is observed before Midsummer.

Rule #3: The next summer will contain a third Litha if the first crescent of the after Giuli is observed within the eves of Christmastide (December 24 to January 4).

Stone based his rules around specific Julian or Gregorian calendar dates but suggested that these rules could be modified if desired to make reference to the astronomical phenomena (the solstices) rather than the Julian or Gregorian calendar dates occurring around the time of the solstices. Stone reported that Rule #2 did not regulate the years as strictly as Rule #1, but I did not find this to be the case over a thirteen year period I examined. Stone’s rules are simple to follow and work reasonably well, though I did find some instances in which Rule #1 and Rule #3 gave conflicting results. Rules #1 and #3 also occasionally resulted in the winter solstice occurring in Blodmonath rather than Giuli. I experimented with two-step rules and soon realized that Stone’s Rule #2 was sufficient to coordinate the lunar and solar aspects of the year over a thirteen-year period I examined. I tried both Stone’s original version of Rule #2 as well as a modified version with the astronomical summer solstice date rather than a Julian or Gregorian calendar date as the reference point:
Modified Rule #2: The next month is intercalary if the first crescent of the second Litha is observed on or before the 4th day from summer solstice (generally June 25, if solstice is June 21).

Solstice dates are courtesy of Fred Espenak, With either version of Rule #2, the resulting calendar kept winter solstice within Giuli and summer solstice within Litha, for every year 2013 through 2025. Results are similar but not identical using the two versions of Rule #2. The first two years of the calculation are shown below, and the calendar for 2013 through 2025 (using the 4th day from the actual solstice dates as the reference point) can be downloaded.

New moon (USNO)
Starting date of month – estimate of 1st crescent sighting, time of best visibility, Canterbury (HMNAO)
Month calculated using modification of Stone’s Rule #2 based on 4th day from actual summer solstice dates
1/11/2013 19:44
1/12/2013 16:50
(Æftera) Giuli
2/10/2013 7:20
2/11/2013 17:57
3/11/2013 19:51
3/12/2013 18:27
4/10/2013 9:35
4/11/2013 19:26
5/10/2013 0:28
5/11/2013 20:15
6/8/2013 15:56
6/10/2013 20:39
(Ærra) Litha
7/8/2013 7:14
7/10/2013 20:26
(Æftera) Litha
8/6/2013 21:51
8/9/2013 19:43
9/5/2013 11:36
9/7/2013 18:40
10/5/2013 0:34
10/6/2013 17:37
11/3/2013 12:50
11/5/2013 17:05
12/3/2013 0:22
12/4/2013 16:42
(Ærra) Giuli

1/1/2014 11:14
1/2/2014 16:50
(Æftera) Giuli
1/30/2014 21:38
1/31/2014 17:19
3/1/2014 8:00
3/2/2014 18:29
3/30/2014 18:45
3/31/2014 18:59
4/29/2014 6:14
4/30/2014 19:56
5/28/2014 18:40
5/30/2014 20:34
(Ærra) Litha
6/27/2014 8:08
6/29/2014 20:37
(Æftera) Litha
7/26/2014 22:42
7/29/2014 20:05
8/25/2014 14:13
8/27/2014 19:04
9/24/2014 6:14
9/26/2014 18:09
10/23/2014 21:57
10/25/2014 17:10
11/22/2014 12:32
11/23/2014 16:29
(Ærra) Giuli
12/22/2014 1:36
12/23/2014 16:49
(Æftera) Giuli

The cycle of ordinary and embolismic years happens to be identical to that calculated by Wodening based on the 19-year metonic cycle, at least within the period examined (2013-2025). We don’t know if the early Anglo-Saxons applied a rule like this to keep track of ordinary and embolismic (thrilithi, or three Lithas) years, but it is simple, based on observations of nature, and requires no advanced calculations. It is also interesting to note that the time point for observation is close in time to the Christian commemorations of the Nativity of John the Baptist (June 24) and the Feast of St. Peter and St. Paul (June 29). The Nativity of John the Baptist was set relative to the dates of Christmas and the Annunciation. The Old English poem Menologium notes that the feast of St. Peter and St. Paul was celebrated five nights after Midsummer:

But the apostles
Peter and Paul,
Much celebrated,
Faithful to the Lord,
Five nights
after midsummer,
Suffered at Rome
Grievous torment from the people,
Glorious martyrdom

We can imagine that if the pre-Christian Anglo-Saxons used a calendar observation date shortly after the summer solstice, they may have celebrated the day in some way.