‘Par à travers’: A rare combination of two rival prepositions within the group of analytic spatial prepositions containing French ‘travers’

The prepositions par and à travers (meaning both 'way through/across') belong, in French, to the limited group of the main markers of spatial dynamic relations with a medial polarity; they are directional and often describe a situation where some trajectory moves along a path. A great number of French spatial prepositions, especially static ones, have been the subject of thorough semantic descriptions. By contrast, studies dealing in detail with intrinsically dynamic prepositions remain quite rare (Stosic 2002). Moreover, the literature dealing with par and à travers is purely synchronic and restricted to a small group of uses (mainly spatial or perceptual).
Though they are often considered synonyms, the expressions at hand possess very specific usage patterns that exhibit subtle semantic differences. For example: both par and à travers can introduce the medial ground of a movement. But à travers, unlike par, does not take in consideration the relation of that entity with other elements of the environment and does not presuppose that the motion verb involves some kind of alteration of that relation (Aurnague & Stosic 2002).
As I showed in a previous work (Hoelbeek 2007), à travers became significantly more frequent from the 18th Century on, apparently at the expense of au travers (de); but à travers (partly) replaced the preposition par as well. Indeed, the use of the descendants of Latin per decreased gradually, a development for which the increasing use of the expressions with travers seems to account ('se promener par la campagne' vs 'se promener à travers la campagne').
The fact that these two prepositions (which may commute with each other in some contexts, but are characterised by different usage patterns in other contexts) are combined in one unique prepositional expression is most extraordinary. The tokens I found when consulting the digital database Frantext are relatively few, and confined to specific periods: the combination was only used in the 16th Century (two different authors), in the 19th Century (one author only), and in the 20th Century (two different authors). For the combination par au travers de, formed with a prepositional expression close to à travers, namely au travers (de), I found only one token dating from the 16th Century.
The aim of my paper is to analyse the semantic structure of this exceptional combination from a diachronic point of view, by taking into account - among others - the descriptions of Stosic (2002, 2005, 2007), who paid particular attention to the differences between the two prepositions from a synchronic viewpoint. This will allow me to determine whether the merged preposition produced a new, original meaning, or simply an addition of two distinct meanings. Furthermore, I will examine those hypotheses that may account for the reappearance of the combination in the 19th and 20th Century.