A faulty interpretation of "testu"
While Oelmann agreed with Rahn's interpretation of the
St. Gall house as a structure of basilican type, he took
exception to the latter's explanation of the testu[do] square
as a lantern surmounting a smoke hole in the roof above the
fireplace. Such a device, he claims, is attested to neither by
classical nor by medieval house construction. He suggests,
instead, that what the drafter of the Plan of St. Gall had
in mind is more likely to have been a huge freestanding
chimney stack on pillars or arches, which rose from the
ground to the ridge of the roof, protruding through the
latter, and ejected its smoke into the open air (fig. 274).[31]
But here again the reader is not furnished with any corroborating
historical evidence. That Rahn's testudines have no
equivalents in classical Greek and Roman architecture may
well be the case, but the assertion that they are not attested
to in the Middle Ages is easily contested.
[32]
And as far as
Oelmann's own suggestion is concerned, it must be pointed
out that all the presumptive medieval parallels that he
adduces turn out upon inspection to pertain not to houses
but to kitchens.
[33]
The reader will recall that the squares on
the Plan of St. Gall which are alternately designated as
locus foci and as
testu[
do] are by no means confined to the
houses for distinguished persons. They are an integral part
of even the humblest among the stables. It is difficult to
imagine that an extremely tall and costly masonry stack
such as Oelmann had in mind should have adorned the
houses of swineherds, shepherds, and goatherds at a period
when such devices were a novel rarity even in the dwellings
of the nobles. Most perplexing of all, however, is
Oelmann's identification of the term
testu[
do] with "chimney
stack"—an equation that finds no support on any
grounds—since it is neither possible to demonstrate that
the term was ever used in this sense in classical or medieval
Latin, nor reasonable to presume that it might ever have
been used in this manner. Its basic meanings (protective
shield, covering lid, tortoise, turtle shell
[34]
) are in outright
conflict with the idea of a hollow flue or duct which underlies
the concept of a smokestack.
