Imagine yourself a squaddie in the Roman Army of occupation of Scotland around 170 AD, stationed at Trimontium, adjacent to the River Tweed. You have been ordered out of the fort to collect firewood: a crucial resource in a Border’s winter for the five hundred or so auxiliaries from central or eastern Europe or Asia Minor. Your horse-drawn two-wheeled cart (carrus) with a safe working load of half a tonne is very overloaded. As you turn into the gate, the cart jumps out of the groove worn in the stones at the entrance, there is a very loud crack and one of the wheels buckles. The cart collapses, spreading the logs onto the frozen ground. The load is more valuable than the cart, so the broken wheels are removed and (because the carpenter is away) are thrown into a pit, covered with soil to hide them, and forgotten. That is, until about 1910 when they were excavated, still in an extraordinary state of preservation, by an Edinburgh solicitor still in an extraordinary state of preservation. [1]
The hub (or nave) of the wheel had been turned on a lathe and was made of elm. The spokes, of willow, were also turned on a lathe. Most interesting is the felloe: the wooden ring onto which the iron tyre was fitted. Usually fabricated out of six separate segments carved to the exact curve of the wheel, this was made of one piece of wood, bent into a perfect circle and held into position by the tyre. The felloe came from a relatively slow-growing tree, and it had failed at the junction with one of the spokes (see below).
There is only one tree in Britain that could be bent into a complete circle without fracturing: Ash.
The structure of Ash is peculiar in that it has vasicentric axial parenchyma: energy-absorbing cells laid down around the edges of the vessels. The faster it grows, the stronger it is. This felloe was made from a 3.1m length of slow-growing coppice Ash, and that might explain its failure.
The use of a tough but turnable timber, Elm, for the hub, along with easily-procurable, flexible willow for the spokes (strong in compression, light of weight) and flexible, strong Ash for the felloe are notable. However, the expertise shown in the choice of the three timbers for this wheel should not come as a surprise to us, given the environmental knowledge displayed by early authors writing at about the same time as the wheel was made, some of whom are the subject of this essay. Timber has been a primary raw material for thousands of years, and has been written about since at least archaic Greek times. In a wide-ranging and authoritative paper Makkonen (1967) mentions over one hundred Greek and Latin references to different tree genera and species in literature covering a thousand years. [2]
The motivation for writing these didactic homilies on nature may not be obvious given the limited distribution each had. However, the fact remains that they represent collective knowledge based on practical observation and experience, and that they were sufficiently relevant to have survived for a couple of thousand years. The beauty is that we now understand the structure of timber, at microscopic level, which supports these earlier observations. An example is the structure of Ash, previously mentioned and illustrated above.
From the hundreds of references to the use of trees among authors such as Cato, Columella, Varo, Virgil and Pliny, writing around the first century AD, I offer a mere handful.
Perhaps the most exciting come from the second book of Georgics of Virgil, lines 439-453:
Line 440. The reference to pine at high elevation in the Caucasus exposed to the East wind (that is, on the East-facing slopes of this mountain chain) is puzzling. Certainly, pines (and other conifer, namely cypress and cedar) grow at high altitude in those mountains, and would probably make exceptional masts, but those exposed to East winds are on the slopes adjacent to the Caspian sea, a distance by road of over 2,500 miles to Italy. An impossible distance to transport timber for ship or housebuilding two thousand years ago. This would suggest that the reference to high Caucasus is a metaphor for the idea that the strongest trees come from the highest altitude. The peaks of the Caucasus are the highest in Europe, unscalable at the time Virgil was writing and thus the place of gods and myth.
Line 444. The evidence presented above shows that lathe-turned wood of an appropriate type (elm, lime, olive etc) was commonplace. Depictions of solid wheeled wagons in carvings on early graves and the like have been found in Northern Italy from centuries before the Empire. Recently, a neolithic solid-wood wheel of Ash has been excavated in Slovenia. It is also relevant to note that wheels with spokes were made as far back as the 6th century BC in Northern Italy. [3]
Lines 447, 448. The use of Myrtle (Myrtus) and Dogwood (Cornus) for the hafts of spears may come as a surprise to British readers, for at least two reasons. First because the majority of hafts that have survived since the Roman Empire have been of Ash or Hazel , and second because Myrtle in Britain is a low-growing shrub. [4] However, the genus contains around fiftyspecies scattered throughout the world. Of these, two are natural around the Mediterranean that, if coppiced, could have produced good hafts given the toughness of the timber.
Yew (Taxus) has been the preferred timber for archery bows for at least six thousand years, usually made with dense heartwood subject to compression in the belly, and more flexible sapwood in tension on the outside. The species has a trans-European distribution which includes the hills north of Galilee (Iturea). The Imperial Roman Army of Virgil’s time (1st century AD) employed auxiliaries as specialist archers.
449-450. Lime (Tilia) is recommended elsewhere (Bk1, line 173) for carving into yokes for beasts of burden, because of its light weight, softness and ease of carving, and was the preferred wood of the master English carver Grinling Gibbons in the 17th century. In contrast, Box (Buxus) is very slow grown and dense, and was engraved with exquisite precision by the bird artist Thomas Bewick in 18th century Britain.
451 Alder (Alnus) is a species that grows best next to, or in water. The timber is soft and easily worked, and when saturated can last for centuries. For those reasons, it was hollowed out and carved to form water-pipes each of which has one end tapered to fit into its neighbour.
Thus, within these fifteen lines of ancient text, the uses of at least nine species of tree are mentioned, most of which are familiar and seem appropriate to their use to modern Europeans. Virgil has examples of other uses of timber that are subtly modern. Encouraging the growing of food rather than its collection “by shaking an oak in the woods” [Bk 1 line 160], he describes how best to create the plough-share beam which holds a specific bend so that the share bites into the soil: “Continuo in silvis magna vi flexa domatur in burim, et curvi formam accipit ulmus aratri ”[Bk1, lines 169, 170]. The lines are translated (by C. Day Lewis) as: “Early in woods the elm, by main force mastered, is bent into a share-beam and takes the shape of the curving plough”. The essence here is to take a pliable one year-old elm sucker, bend and restrain it until it takes up the appropriate hockey-stick shape and then leave it to grow perhaps for another ten years, keeping it restrained until it is of a size to harvest. The internal vessels now following the bend in the stem, the curvature is as strong and stable as is possible. This process of shaping the growth of live wood was, of course, accepted practice in Britain creating “knees” in oak for the building of wooden ships and houses.
Other authors’ instructions are even more detailed. Cato (soldier, orator and the first of a group of Roman writers on husbandry) laid down precise instructions for the building of a press (for olives or wine is not clear). They include the specification of the main beam, of oak, “2 feet by 1 foot by 37ft long”[5]. Weighing one and a half tonnes in its green state, the felling of a tree of this size and its conversion and transport to an ordinary domestic setting show a sophisticated people used to accurate standardized measurement, and an organization that can manipulate heavy, awkward loads. It also says something about the quality of the forest from which the tree was to be selected.
These treatises by Virgil, Cato et al were designed to be used: in Virgil’s own words on growing fruit: “So come, you countrymen, learn the correct training of each in its kind, domesticate wild fruits by your cultivation, and let not earth be lazy! It’s good to plant with vines Ismarus, and to clothe in olives Mount Taburnus.” (Bk II 35-38) Do they have relevance now? Yes, in general if they teach us how to observe and how to think. And in other, less-expected ways.
For example, in the 1970’s in Britain we attempted to understand the origins of the disease which destroyed our elm, Dutch Elm Disease. English Elm (Ulmus procera) produces masses of seed, but none of it is fertile. Given that the pollen record shows a sudden devastating decline of Elm in the neolithic, we might wonder how the species re-populated Britain. One suggestion was that, like other species, it was introduced by the Romans. How could that be examined other than by excavation? Study of these books (with their emphasis on viticulture) revealed that Elm was planted among the vines to provide structural support in a living framework, whose leaves could be harvested as fodder and whose branches pruned and trained to interlink into a living hedge. [6] Since there is little doubt that Roman occupiers of Britain produced their own wine, it is feasible that they brought Elm with them.
It is deeply regrettable that two of the most important tree species, Elm and Ash, described in these two thousand-year-old writings have, or will soon become, extinct in Europe. The reasons lie in the movement of plants across continental boundaries – here our desire to import Rock elm from North America, and Ash from South East Asia. Both carried pathogens with no competitors in Europe. Now, with air travel and the use of containers on fast ships, travel times are not sufficiently long to kill exotic pathogens in transit, in contrast with the major plant collecting periods of the past when sailing ships were used. It is ironic if all that remains of these wonderful, utilitarian trees are words from the ancient past. We now know how to prevent this movement of pest and disease, but we seem powerless to do so in the face of trade and vested interests. Decisions that directly affect the natural environment are increasingly made by business people whose contact with nature is limited to spread-sheet and profit-and-loss account. Maybe, using the words of these tough old soldiers and scribes from the past to remind us of the inherent value of our natural resources, we can effect a change.
Jim Pratt, Scottish Borders, February 2023.
Jim Pratt, MBE, retired as Head, Forest Pathology at Forest Research, Edinburgh, in 2002 after 40 years varied service in Forestry in Britain.
[1] Curle, J. 1911. A Roman Frontier post and its People. Vols 1 and 2. James Maclehose, Glasgow. 431pp
[2] Makkonen, O. 1967. Ancient Forestry: An historical study Part 1. Facts and information on trees, vol. 82 no. 3 article id 7176. https://doi.org/10.14214/aff.7176
[3] Crouwel, J.H.2012. Chariots and other wheeled vehicles in Italy before the Roman Empire. Oxbow Books, Oxford. 234pp.
[4] Bishop, M.C. and Coulston, J.C.N. 2006. Roman military equipment: from the Punic wars to the fall of Rome . Oxbow Books, Oxford. 321pp.
[5] M.Catonis (Cato) De Re Agri Cultura. xviii 4-9.
[6] Virgil Georgics II 358-3267.
The Pen and the Plough 
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