University of Virginia Library

V.15.3

THE MORTARS

MAN- OR WATER-POWERED? CONFLICTING VIEWS

The crushing devices designated by the term pilae, i.e.,
"pestles," in the house lying west of the Mill (fig. 438),
raise the same problems posed by the milling apparatus.
Were they operated by hand or water? Keller, in this case
too, took the first position. He drew attention to two old
hand-operated mortars which he discovered in the remote
village of Beltis on the lake of Wallenstadt in Switzerland
(fig. 449 A.1, A.2).[503] One was three feet high, cut out of a
solid trunk of oak, with the interior hollowed out conically.
The pestle, likewise, was made of a single piece of oak,
except for its handle, and was studded with nails at its
base. This, Keller thought, must have been the contrivance
that the drafter of the Plan of St. Gall had in mind when
he drew his peculiar L- or key-shaped pilae (fig. 438).

[ILLUSTRATION]

451. HOKUSAI. JAPANESE TRIP-HAMMER (19th cent.)

[after Singer, Holmgard, Hall, II, 1956, 107, fig. 71]

If his expression of grim determination is an indication, the man acting as
counterweight to the hammer could scarcely have worked harder using a mortar
and pestle for his task.

That instruments of the Beltis type were used during the
Middle Ages is beyond question, and easy proof of this
may be found inter alia in a delightful marginal drawing
of the Luttrell Psalter (fig. 449C), which shows a bearded
cook pounding a huge mortar with a pestle almost twice
his own height.[504] The mortar, apparently made of iron or
bronze, reaches to slightly above the knee of the pounding
cook, and by that criterion should have been meant to have
a height and width of roughly two feet. The largest implement
of that type I have ever examined is a mortar carved
of a single block of stone, that stands now in the medieval
granary of the Abbey of Le Thoronet in Provence, only a
few yards away from the millstone discussed in an earlier
part of this chapter. This mortar (fig. 449B) has a round
base, 2 feet in diameter, is 3½ feet high, and 4 feet wide at
the top. Its pounding cavity tapers from the rectangular
opening at the top to a conical form at the bottom. The
pestle—which does not look to me to be the original—is
a roughly hewn trunk of a young tree, about 9 inches thick

and nearly 5 feet high. In testing it on the spot it seemed to
me that it could be worked with some effort by a single
man, and with ease by two men lifting it in conjunction.

Yet I would be inclined to think that in the Middle Ages
mortars and pestles of this order of magnitude were water
driven, rather than hand-operated mechanisms. This was
also the view of Rudolf Meringer who has made a special
study of this type of instrument. In an article on the implements
of the pinsere series and their names, published in
1909, Meringer[505] drew attention to the fact that the pilae
of the Plan of St. Gall (fig. 438) were not only considerably
larger than those with which they had been compared by
Keller (fig. 449A) but also of vastly different shape. He
claimed that, rather, they bore striking resemblance to a
type of crushing device which in German is called Anke,
and illustrated his views by a startling juxtaposition of the
pilae of St. Gall and a drawing of a modern water-driven
iron hammer (fig. 453).[506] The earliest pictorial representation
of a water-driven recumbent western tilt-hammer
appears to be a woodcut in Spechthart's Flores Musicae,
published in 1488 (fig. 455).[507] In an earlier period this contrivance
was operated by hand or foot, as it was still in very
recent times in Galicia (fig. 450), Poland, China, and
Japan in very much the manner in which this is depicted
in a whimsical drawing by the Japanese painter Hokusai
(fig. 451). Man-powered tilt-hammers of this type, as was
subsequently shown, were used in China in remote periods,
and their design and mode of operation is well attested by
two small models in green glazed pottery from the Han
period (206 B.C. to A.D. 220) which are now in the Nelson
Art Gallery (fig. 452A-C), Kansas City, as well as a Han
moulded brick found at P'en-shan Hsien, in the Szechuan
Provincial Museum, Chengtu (fig. 452D).[508] Meringer
was convinced that the pilae of the Plan of St. Gall
did not belong to the foot-operated type, but that they were
water driven, and he attempted a reconstruction (fig. 454),
in which the pestle beams were alternately lifted and
released for fall by the cogs of a cylindrical drum mounted
directly upon the axle of a water wheel, as in the modern
iron hammer (fig. 453). Hydraulic trip-hammers of this
or a similar design are attested for China through unequivocal
literary descriptions as early as the reign of Emperor
Wang Mang (A.D. 9-23) and through less reliable sources
perhaps even as early as the third century B.C.[509] Meringer
could not prove that the camming action employed in this
device was known in Carolingian times,[510] and his interpretation
of the pilae of St. Gall as hydraulic cam-operated
pounding mechanisms did not come to the attention of
Marc Bloch who, in his classical and widely read study on
the advent and spread of the water mill, referred to the
pilae of St. Gall as "a crushing instrument which, on the
plan, was certainly not shown as being water driven;"[511]
a view which was reiterated in 1954 by Bertrand Gille,[512]
and subsequently adopted, although perhaps not with the
same degree of conviction, by Lynn White in 1962.[513]
Finally, in 1965, it looked as though Meringer's interpretation
had received a final blow, when Joseph Needham,
in his monumental Science and Civilization in China, after
a thorough account of the Chinese history of the hydraulic
trip-hammer[514] advanced the theory that this mechanism
was introduced in Europe "about the time of Marco Polo,"
in connection with the fulling trade when much other
Chinese textile machinery appears to have made its way to
Europe. Needham proclaimed that all water powered European
stamp mills prior to that period were machines in
which pestle beams moved in vertical action in the manner
illustrated by a drawing made by an anonymous Hussite
engineer around 1430 (fig. 456).[515]

EVIDENCE FOR WATER-POWERED TRIP-HAMMERS

The Plan of St. Gall contradicts these views. The pilae
of its Mortar House can under no circumstances be interpreted
as vertical pestles. Their design—a hammer attached
at right angles to a pestle beam connecting at the opposite
end with a body of cylindrical shape—leaves no doubt
that they were recumbent hammers activated by the cams
of a revolving drum. Their dimensions as well as their
location, next to a water-driven grain mill, suggests that
they were water powered. The pestle beam alone is 10 feet
long (4 standard modules), the hammer has a length of 6
feet (2½ standard modules) and the drum has a diameter
of 6¾ feet. The over-all length comes close to 17½ feet. This
is a very heavy piece of equipment that could not possibly
be operated by hand or foot. The Plan may somewhat
exaggerate the dimensions of the drum,[516] but it leaves no

[ILLUSTRATION]

452.A MODEL. FARMYARD DETAIL WITH FOOT-OPERATED TRIP-HAMMER. HAN DYNASTY, 206 B.C.-220 A.D.

IRRIDESCENT GREEN GLAZED POTTERY, 8¾ × 6 × 2½ INCHES

question about the presence of a drum, which makes sense
only within the context of a water-powered apparatus.
Marc Bloch's argument that water is not shown on the
Plan, does not militate against this conclusion. We have
shown in our chapter on omissions and oversights how
waterways, although nowhere in evidence on the Plan,
could be a determining factor in siting of facilities dependent
on this power source, and were therefore clearly a
possibility taken into account by the designing architect.[517]

The crushing mechanisms of the Mortar House of the
Plan of St. Gall are, as far as I can see, the earliest historical
evidence of the use of hydraulic trip-hammers in Western
Europe. Their appearance on the Plan makes it clear that
water-driven trip-hammers were, at the time when the
original scheme was drawn, i.e., in 816-817, considered
standard equipment of a paradigmatic Carolingian monastery.
There is no reason to presume that the inventor of the
scheme was also the inventor of the mechanism. The
system as such may, even in Europe, have been of considerably
greater age. It may have been diffused in Frankish
times from China, as the stirrup certainly was, as the two
forms of modern horse-harnesses probably were, and as
the mechanical crank may have been.[518]

A SURVIVING MEDIEVAL HYDRAULIC TRIP-HAMMER

I feel strengthened in this conjecture by the circumstantial
historical evidence surrounding a water-powered
medieval trip-hammer that came to my attention, in the
summer of 1970, while travelling in the mountains of the
province of León in Spain. This mechanism, not only
intact but able to be operated, is housed in a smithy located
in the valley of Compludo, on the grounds of a former
monastery of that name. San Fructuosus, a Visigoth of
royal blood and the founder of Spanish monachism, established
Compludo as the first of a vast web of monasteries.
The trip-hammer owes its anachronistic survival to the

[ILLUSTRATION]

452.B

The processing of grain for domestic use
in China during the centuries just before
and after the birth of Christ in the West
reveals wholly familiar technologies and
associations. The model of the farmyard
(fig. 452. A) contains, in addition to the
trip-hammer, a small mill and what
appears to be a parching kiln built into an
enclosure wall—an association also
reflected in the Plan of St. Gall, some 6
centuries later.

The trip-hammer in the model (figs.
452.A-B) was the simplest of mechanisms;
in it is applied the principle of fulcrum
and lever actuated by direct force.

452.C

WILLIAM ROCKHILL NELSON GALLERY OF ART, ATKINS MUSEUM OF FINE ARTS, KANSAS CITY, MISSOURI

IRRIDESCENT GREEN GLAZED POTTERY, 10¾ × 3½ × 3½ INCHES

complete and utter isolation of the site, which even today,
is accessible by only a stony mountain road whose narrow
and precipitous course offers to the unexpecting modern
visitors moments of breathtaking suspense.[519] The instrument
is described by Florentino-Augustin Diez Gonzáles,[520]
in a study of the political and social life of the Spain of San
Fructuosus, which also includes a sketch of this unusual
mechanism.[521] It conforms in all respects to the trip-hammer
shown in Spechtshart's woodcut of 1488 (fig. 455)
and the modern specimen discussed by Meringer (fig. 453),
except that it is considerably larger.

The water that sets the Compludo hammer into motion
is channeled from the confluence of two narrow mountain
streams, the Miera and the Miruello, into a collecting
basin (banzao) from where it falls upon the heavy wooden
studs of a waterwheel. This wheel, 8 feet in diameter, is
driven by a shaft (árbol) made of chestnut, 16 feet long
and 2½ feet thick. Rotating horizontally this timber,
hardened by age like stone, activates with its wooden cogs

[ILLUSTRATION]

452.D CHENGTU, SZECHUAN, PROVINCIAL MUSEUM

RUBBING, CLAY TOMB TILE, (46 × 28cm) DETAIL, EASTERN HAN PERIOD, 23-220 A.D.

[after Liu Chih-yuan]

Two men are shown pounding rice with trip-hammers, a scene of daily life of the lower social strata of Chinese society that artists of the
Eastern Han loved to portray.

The tile was excavated in 1956 at T'ai-p'ing-hsiang, P'enghsien, Szechuan Province. It was published in Ssu-ch'uan Han-tai hua-hsiang
pei-t'o p'ien (Portfolio of Han Dynasty Impressed Clay Tiles from Szechuan), Ssu-ch'uan sheng po-wu-kuan (Szechuan Provincial
Museum) by Shang-hai jen-min mei-shu ch'u-pan she (Shanghai People's Art Press), 1961, pl. 3, from which this detail is taken.

[ILLUSTRATION]

453. MODERN TILT-HAMMER (SCHWANZHAMMER)

PLAN AND SIDE ELEVATION

[redrawn after Meringer, 1907, 285, fig. 10]

The cam block driving the hammer can be linked to a drive system
as sophisticated as one powered by steam, or as simple as one driven
by an animal on a treadmill.

a sturdy lever (palanca), 13 feet long, at whose extremity the
smashing hammer (mazo) rises and falls. The rhythm or
beat of the stamp can be controlled from within the forge
by a second mechanism that augments or decreases the flow
of the water turning the wheel, as the varying nature of the
work requires (sketched roughly in Gonzáles's drawing).
The ore is smelted in the furnace by a fire fanned to intense
heat by means of air drafted into it by hydraulic action
(shown in the background of Gonzáles's sketch) and under
the beat of the hammer, converted into malleable iron.[522]
To watch this primordial mechanism in operation was
truly an awe-inspiring experience.

MONASTIC ECONOMY AND WATER POWER
UNDER ST. FRUCTUOSUS

The date of the hammer is unknown.[523] Local tradition
ascribes it to "Romanesque period" (edad romanica).

González believes that mechanisms of this type might well
have been an integral part of the monastic economy of the
time of San Fructuosus (d. 665).[524] This view is not so

[ILLUSTRATION]

455. SPECHTSHART. FLORES MUSICAE

STRASSBOURG, 1488, fol. 7v

[courtesy of the University Library, Freiburg i. Br., Germany]

The woodcut shows an iron forge with a water-powered tilt-hammer
activated by a cylindrical cam block mounted on the axle of a waterwheel.
Two blacksmiths forge iron on an anvil with the hammer's
aid; behind them Pythagoras weighs hammers. In the background,
Tubal chisels musical notes into a column, representing Pythagorean
philosophical preoccupation with order, number, and harmony of the
spheres of the Ptolemaic universe (cf. I, 231, fig. 187).

shocking as it might appear to be at first exposure. The
seventh century, as has been shown in the preceding
chapter, was the great century of systematic application of
water power to milling in the economy of coenobitic
monachism.[525] The development was spurred by the need to
provide great quantities of flour for the sustenance of large
numbers of men whose religious activities required that they
be freed from certain common forms of labor, in order to
devote themselves to the more serious task of serving God
in prayer and chant. It is not an unreasonable conjecture
that the same need may also have fostered the invention or
adoption of the cam which made it possible to harness water
for tasks requiring the crushing blow of a rising and falling
mechanical hammer. It is quite possible that this idea (or
its adoption) was first conceived in connection with iron
works where the brutal blow of a hydraulic stamp offered
advantages highly superior to those that could be derived
from its use in the lighter task of crushing grain or of
fulling cloth. The banks of the rivers in the mountains of
Eastern Leon, where San Fructuosus founded his first
monasteries, carry iron deposits important enough to be
mentioned by Pliny the Elder and other Roman writers;[526]
numerous localities in this area, now in ruins or deserted,
carry even today the name herrería (iron forge).[527]

The Fructuosan monastic economy formed an ideal
ambiance for the invention of such a power mechanism. It
created a sudden and vast demand for agricultural tools by
converting virtually overnight deserted valleys into densely
populated rural communities, formed not only by the
multitude of monks that settled in the monastery itself, but
in addition by a veritable army of secular followers who
were allowed to establish themselves as tenants in the vast
stretches of land which the monastery owned in the valleys
and mountains around it. Among them were members of
the former household of San Fructuosus (whose paternal
inheritance was enormous), magnates from the royal court
with their entire families, soldiers from the Visigothic
army who fell under the spell of the saint, and in a mystical
commotion that had no precedent, followed him in such
numbers that their chieftains found themselves compelled
to legislate against such wholesale desertion of the army
and flight into the country.[528] A blacksmith capable of
converting ore into iron with the aid of water power and
shaping it into usable tools could meet the demands created
by such a sudden population increase in the country, and the

[ILLUSTRATION]

VALLEY OF COMPLUDO, LEÓN, SPAIN. MEDIEVAL IRON FORGE & WATER-POWERED TRIP-HAMMER,
WITH FORGE BLOWER ASSOCIATED WITH FLUME. Date of the initial installation unknown,
concept possibly dating from Visigothic period. See caption above.

457.A

PERSPECTIVE VIEW

In 1975 we paid another visit to the Compludo
forge and discovered that the trip-hammer we
first inspected in 1970 was being rebuilt, and the
waterwheel replaced by a slightly sturdier one.
The hammer had been moved to the outside yard
to serve as a template for its replacement. The
sturdy cammed trunk, strongest member of the
mechanism and subject to great torsional strain,
was considered in good enough condition to serve
another span in the life of the hammer. It had
earlier been reinforced lengthwise by iron bars
banded to it with iron hoops.

The carpenter directing the work was convinced
that in continuous use, wheel and hammer would
need replacement every 40 years, the main trunk
every century. He shared local belief that the
mechanism is medieval and would tend to retain
its original design for a virtually indefinite span
of time, even though its components were
periodically renewed.

These drawings were made with aid of measurements
taken in 1975. They do not show the
apparatus governing the flow of water to the
wheel and thus the speed of the hammer's
action. For rough sketches of that mechanism
and the means by which air is drafted into the
forge furnace, a function also associated with the
flow of water to the wheel race, we still depend
exclusively on the drawing published by
Gonzáles (1966, 46) and reproduced by Horn
(1975, 245).

457.B

457.C

457.D

presence of ore in these places would give an added stimulus
to the adoption of devices facilitating their production.

The Romans, it is generally conceded, did not make any
use of water-powered trip-hammers transmitting the
rotational movement of the wheel and its axle into the
vertical beat of a recumbent hammer by means of cogs.
China, unquestionably is the prime inventor. But the Plan
of St. Gall attests that at the beginning of the ninth century
such mechanisms were, even in the West, well known and
widely employed. This seems to vitiate the theory of its
westward diffusion by Marco Polo and suggests that the
knowledge of this invention came to Europe in the wake of
contact established with the Far East, in the fourth and
fifth centuries A.D. by the invasion of the Huns and other
Asiatic tribes, with whom the Visigoths were in close, and
often mortal, association over long periods of time.

FROM CHINA TO EUROPE DURING THE
MIGRATION PERIOD?

The display of water-powered trip-hammers on the Plan
of St. Gall gives added credence to such literary sources
as had been adduced by Bloch, Gille and Carus-Wilson[530]
in favor of the contention that hydraulic trip-hammers were
operated in eleventh- and twelfth-century Europe; as well
as the claim advanced by Uccelli and White[531] that the fulling
mills of Prato made use of hydraulic trip-hammers from
the beginning of this industry in A.D. 983.[532] An even
earlier reference (datable 883-904) to molinis vel pilis is to
be found in the Formulae Sangallenses miscellaneae.[533]

EUROPEAN SOURCES BEFORE MARCO POLO

A literary account of poetic beauty of water-driven
trip-hammers, written decades before Marco Polo's visit
to China (A.D. 1280), is to be found in a remarkable thirteenth-century
description of the waterworks of the monastery
of Clairvaux. There, after telling how the river Aube
had been deflected from its natural course, the writer
traces the water's path as it travels from workshop to
workshop, "launching itself at once upon the wheels of the
mill, and lashed into foam by their motion, it grinds the
meal under the weight of the millstones, and separates the
fine from the coarse by a sieve of fine tissue." Then, after
a brief excursion into the brewery, "where it fills the
boiler and is heated for brewing. . . not hesitating nor
refusing any who requires its aid," it follows the call of the
fullers, at whose workshop, close by the mill, "you may
see it causing to rise and fall alternately the heavy pestles,
that is to say, hammers or wooden foot-shaped blocks—for
that name seems to agree better with the treading-work, as
it were of the fullers—and so relieves them of the heaviest
part of their labor" (sed graves illos, sive pistillos, sive malleos
dicere mavis, vel certe pedes ligneos—nam hoc nomen saltuoso
fullonum negotio magis videtur congruere—alternatim elevans
atque deponens, gravi labore fullones absolvit. . .)[534]

TRIP-HAMMERS WITH VERTICAL PESTLES

There existed in the Middle Ages, as already mentioned,
yet another pounding mechanism making use of camming
action that cannot be overlooked in this context. It worked
with vertical pestles rather than with recumbent hammers.
Illustrations of these are found in the Mittelalterliche
Hausbuch of about 1480,[535] in several manuscripts of
Leonardo da Vinci[536] and in the manuscript attributed
to an anonymous Hussite engineer of around 1430 (fig.
456). Needham considers these vertical stamping mechanisms
"as characteristically European as the recumbent
tilt-hammer was Chinese."[537] This may be true, but there
is no historical assurance whatsoever that in Europe the
invention of the former preceded the adoption of the
latter[538] and any attempt to interpret the pilae of the Plan
of St. Gall, or the pistillos, sive malleos, vel certe pedes
ligneos of the thirteenth-century description of the water-powered
trip hammers of the Abbey of Clairvaux in the
light of this vertically operated pounding mechanism
would be straining the available historical evidence beyond
the limits of propriety. Amongst the vertical medieval
crushing devices listed by Needham, or anyone else
as far as I can see, there is not a single one with pestles
the shape of which could in any manner be compared
with that of a hammer (malleus) or a foot-shaped member
(vel certe pedes ligneos). A hammer, whether struck horizontally
or vertically, hits its object on impact, in a position
which places its longitudinal axis parallel to the surface
that receives its blow. It can accomplish this only with the

[ILLUSTRATION]

PLAN OF ST. GALL. MORTAR HOUSE. AUTHORS' INTERPRETATION

458.B

458.A

458.D

458.C

PLAN. TRANSVERSE SECTION, LONGITUDINAL SECTION; SOUTH ELEVATION

The Mortars of the Plan are here reconstructed as water-driven mechanisms, with their axle-trees oriented east and west and the presumptive
waterwheels to which these were geared oriented in the same direction, as are the waterwheels of the reconstructed Mill (above, fig. 448. A-E).

[ILLUSTRATION]

PLAN OF ST. GALL. AUTHORS' RECONSTRUCTION

458.E

458.F

WEST ELEVATION, NORTH ELEVATION

If a stream existed on the site and the land gradient permitted the development of waterpower, great efficiency could be achieved by this
alignment of the wheel races. For justification of water-powered mechanisms see above, p. 232, caption to fig. 448. In actual construction, we
believe such details would have been resolved by experienced craftsmen.

aid of a "foot-shaped" head piece lying at right angles to
its longitudinal axis. In the vertical crushing mechanism,
illustrated by the anonymous Hussite engineer (1472-78),
the Hausbuch Master (ca. 1480) and Leonardo da Vinci
(turn of the fifteenth to the sixteenth century), the pestles
are pointed, i.e., pencil-shaped, and could not by any
stretch of the imagination be interpreted as "hammer-" or
"foot-shaped" instruments. There is no doubt in my mind
that the pilae shown on the Plan of St. Gall must be interpreted
as recumbent hammers. They have the shape of
hammers, and the presence of a drum at the end, which
lies opposite the head of the hammer, as well as their
dimensions, allows for no other interpretation.[539]

RECONSTRUCTION OF PILAE ON THE
PLAN OF ST. GALL

Using as a model the trip-hammers of the iron forge of
Spechtshart's Flores Musicae (fig. 455), the trip-hammer of
the monastic smithy of Compludo (fig. 457), and the modern
example described by Meringer (fig. 453), we have reconstructed
the mortars of the Plan of St. Gall as water-driven
crushing hammers whose movement is controlled by the
cogs of a cylindrical drum mounted directly upon the axis
of a waterwheel (fig. 458).

DIETARY IMPORTANCE OF CRUSHED GRAIN IN
WESTERN EUROPE

The amount of crushed grain used daily in a medieval
monastery must have been considerable. A mixture of
barley and oats, made into a kind of porridge or "pap" by
the crushing action of the mortar was a chief item in the
diet of the people of Western Europe prior to the introduction
of the potato. The German word for this dish is mus,
and in the monastery of St. Gall the use of this term, as

[ILLUSTRATION]

459.A PLAN OF ST. GALL. DRYING KILN. AUTHORS' RECONSTRUCTION [1:192]

The shelter for the Drying Kiln is identical with those for the Mills and
Mortars of the Plan. This house could have been the simplest kind of structure,
perhaps even open-sided. Although the Drying Kiln would not develop
temperature so high as those needed for baking, some fire hazard would have
existed in a closed building; the Plan does not show either smoke exit or stack
port for this facility. We reiterate that these service structures of the Plan are
highly abstract; their purpose and siting were of foremost importance to the
Plan's makers; their constructional details, secondary.

Keller has pointed out,[540] was so prevalent that the monk
Kero renders the Latin word cibus, i.e., "food," with the
German word mus, and caenare, i.e., "to take one's supper,"
with the term abendmussen, i.e., "to sup on pap."

Crushed grain was also one of the primary ingredients in
the making of beer.[541]