------------ EH.NET BOOK REVIEW --------------
Classic Reviews in Economic History
Abbott Payson Usher, _A History of Mechanical Invention_. New York:
McGraw-Hill, 1929. xi + 401 pp. (Revised edition, Cambridge, MA:
Harvard University Press, 1954, 450 pp.)
Review Essay by George Grantham, Department of Economics, McGill University.
How Economic Change Happens: Usher's _History of Mechanical Invention_
Among the seminal works in economic history fewer are more perplexing
than Abbot Payson Usher's _History of Mechanical Invention_. The
bland title offers no suggestion of a great ambition, which is
nothing less than to establish logical foundations for an empirically
based explanation of economic change, the prose is stern and
unrelenting, and like a car that runs out of gas just before reaching
its destination, the book simply comes to a stop with no conclusion,.
Few historians consult the work today. Once ransacked for information
on the early history of clocks, windmills, textile machinery, steam
engines and machine tools, its encyclopedic function has been
superseded by more accessible and up-to-date compilations. So why
should we be tempted to study it now? What gain repays the effort
required to master the technical minutia of several branches of
mechanics and the erudite byways of classical and medieval
scholarship? The main reason is that, along with Kuznets' studies in
historical income statistics, _The History of Mechanical Invention_
is a founding text of a science dedicated to explaining economic
change, what Usher called the "mutual transformations taking place
between human societies and their environment."
We begin with the pesky problem of how to tell that story. At the
time Usher was composing the first edition of _Mechanical Invention_
(1929), the narrative of general economic history was dominated by
the "stages" approach, according to which the development of
individual economies is displayed in a chronological sequence of
conceptually distinct types. Conceiving economies as identifiable
types goes back to generalizations proposed by the ancient Greeks to
interpret the customs of the strange peoples they encountered in Asia
and the European hinterland. In the eighteenth century the notion
received a fillip from speculations attributing the evident
segregation of human societies by type to adaptation to different
geographical conditions. Adam Smith's four-fold classification of
societies into hunting and gathering, pastoral, agricultural and
commercial economies is an unexceptional instance of this reasoning.
As individual types were considered to reflect static environmental
constraints, the typology contained no chronological implications, so
that although Montesquieu, Smith and Turgot certainly believed that
commercialized societies represented an "advanced" state of
civilization, they held no strong view that it represented the latest
phase of an historical sequence. Indeed, the conviction that men are
physically and psychologically similar and the great prestige of
Roman civilization stood in the way of a progressive narrative of
social states. Reason is timeless.
In the hands of early nineteenth-century philosophers exalted by the
Romantic concept of becoming, that static conception of social types
acquired a temporal dimension. To position societies on the thin line
of Time's Arrow, however, implied that they are discrete entities
historically expressing ontogenetic development that is independent
of the particular environment. But exactly what force causes such
entities to cohere and persist, and drives their historical
development? The cause could not be definitely stated, any more than
one could then explain ontogenetic development of living
organisms.[1] Whatever it was -- life-force, God's will, the national
Geist, it was ineffable. It could be felt, appreciated and asserted,
but not explained. All that could be declared with any degree of
confidence was that each society develops through a sequence of
stages marked by increasing complexity of organizational forms,
methods of production, degrees of regional and occupational
specialization, and movement from small to large units of social and
economic organization.
In the different versions supplied by successive generations of
German historical economists and American Institutionalists the
stages approach provided a serviceable framework for characterizing
the range of societies revealed by geographical discovery and the
general trend of European development since the early Middle Ages. It
was a capacious tent within which several generations of economists
and historians were able to get on with the business of investigating
the evolution of the myriad institutions and activities that
constitute an economy without having to worry much about what it all
meant.[2] Yet despite conjectures that recall elements of the New
Institutional Economics, the stages "theory" offered little in the
way of a systematic interpretation of how particular societies
interact dynamically with their environment. It did not explain _how_
things change.
Much the same can be said of the empiricist tradition exemplified by
Clapham's _Economic History of Modern Britain_ (1926). Making
abundant use of contemporary statistical sources, Clapham aimed at
correcting catastrophic accounts of Britain's industrial revolution
concocted from impressionistic sources by asking the quantitative
questions, how much, how often, and for how long. The overall
impression left by this monumental exercise in error correction was
that one can draw few generalizations beyond the fact of the
geographic diversity of England's nineteenth-century economic
experience. To the question, what happened in history, Clapham
answered, many things to many people in many places. A thoughtful
reviewer characterized the work as a tour book laced with numbers.[3]
As Usher observed in a second review, that criticism was unfair.
Clapham had an implicit model of England's industrial transformation,
but left it to the reader to parse it out for himself.[4] Yet,
although honest enough, this leave-it-to-Beaver approach to
historical synthesis was hardly the stuff of a science capable of
building on past achievements. As Darwin had observed sixty years
earlier, a fact is not neutral; it is either for or against an
argument. Clapham refused to argue.
Neither Clapham's sprawling narrative nor the ethereal holism of the
stages approach adequately addressed the main question of how things
change. Kuznets eventually resolved the problem posed by Clapham by
reducing quantitative indicators of output to a scalar measure of
economic activity that tracks the flows connecting income with
aggregate saving and expenditure. That synthesis rests on
well-understood accounting principles permitting one to speak
intelligibly of an economy in time. It utilizes a measure that can be
statistically decomposed to its proximate causes and even unto the
causes of those causes. By contrast, synthesis offered by the stages
vision of economic change achieved only an aesthetic coherence, where
the significance of particular facts depended on their relation to an
a priori compositional scheme. As Usher noted, the rhetorical
persuasiveness is generally secured by "discreet omissions." The
notion that "history," economic or otherwise can be described as the
movement of a holistic entity implies the existence of an immanent
principle determining the whole course of events, which makes it
little more than a thinly disguised Natural Theology, where, as the
Austrian novelist Robert Musil once said of allegory, "everything
takes on more meaning than it honestly ought to have."[5]
Particular Systems of Events
Usher's answer to holistic history was to restrict analysis of
historical causation to sequences of events for which temporal
connections can be empirically demonstrated.
We ought not to say that the present is derived from the past
and the future from the present. The proposition must be
formulated in much more specific terms: every event has _its_
past. The principle of historical continuity does not warrant
any presumption about the relations among events occurring at
the same time. This assumption is very frequently made, but it
will be readily seen that it is not warranted (1954, p. 19).
Usher termed the sequences for which historical continuity can in principle be verified
"particular sequences of events." Such sequences are distinct from
series of events resulting from similar responses to similar
situations, such as the predictable responses of economic agents to
changes in the environment, because a narrative adds nothing to our
understanding of them. As Paul Veyne observes,
If the revolutions of people were as entirely reducible to
general explanations as physical phenomena are, we would lose
interest in their history; all that would matter to us would be
the laws governing human evolution; satisfied with knowing
through them what man is, we would omit historical anecdotes, or
else we would be interested in them only for sentimental
reasons, comparable with those that make us cultivate, alongside
great history, that of our village or of the streets of our
town.[6]
Objects of historical thinking acquire meaning from their place in a
plot that explains them. Usher held that innovation was the critical
element of such plots, because it adds something that could not be
predicted from initial conditions and therefore has to be explained
by links to events preceding it in time.
A particular system of events must therefore be shown to be a
truly genetic sequence. It must rest upon one or more acts of
innovation that have been preserved by tradition and developed
by further innovations (1954, p. 48).
Invention, then, makes up an intrinsically historical element in a
series of events. It cannot be predicted with certainty ex ante, but
it can be explained ex post as a narrative of verified acts. The
_History of Mechanical Invention_ proposed just such a narrative.
How does one identify a particular sequence? What principles make
them distinct objects of empirical investigation? Several
alternatives suggest themselves. One might distinguish events by
their goal or purpose. Usher doubted that this principle could be
applied to technological sequences because there are too many ways to
skin a cat. The boomerang, bow and arrow, and blow-gun all kill game
at a distance, but because they do not belong to the same
technological system of events, none could plausibly have evolved out
of any of the others. The presence of a common scientific principle
suggests a better defining principle, but general principles may be
too broad to define relevant boundaries identifying the particular
sequence. Steam engines and steam turbines both exploit the expansion
of steam to transform heat into mechanical energy, but they employ
radically different mechanical means of doing it. Reciprocating
piston engines descend from a pneumatic technology that originated in
the hand pump; the genealogy of the turbine starts with the
horizontal water wheel. The same is true of the transmission of
motion by gear trains. While the devices invoked common mechanical
principles in watches, clocks, and heavy equipment, the particular
problems facing inventors differed so much from one application to
another that the historian needs carefully to specify the context to
explain the path of invention in each class of application. The
boundaries of particular systems of technological events are thus
narrower than their underlying scientific principles might suggest.
Usher believed that the determination of those boundaries is
ultimately an empirical question, as the boundaries have clearly
widened over time as a consequence of advances in pure and applied
science.
Systems of events consume time. Economists are not much concerned
about the logical status of time except insofar as it serves as the
metronome for growth theory. Not everything happens at the same time,
however, and particular systems of events unfold at different speeds.
One does not see that bicameralism, coitus interruptus, the
mechanics of central taxation, the detail of rising lightly on
one's toes when uttering a subtle or strong sentence (as M.
Birotteau did), and other events of the nineteenth century must
evolve with the same rhythm.[7]
Usher held that intelligible history is necessarily pluralistic.
Particular sequences, which we currently call paths of temporal
dependence, demand separate treatment to track down cause and effect.
A subtler problem concerns the historian's temporal perspective.
Usher insisted that particular events should not be conceived as
constituting the "end" of a sequence.
The temporal sequence of relations is ... incomplete unless we
think of it as a past-present-future system of relations.
Furthermore, the definition of the "present" may be taken either
from the point of view of the observer or the historian, or
from the point of view of any particular event. In fact, the
necessity of reading time series forward really commits us to
adopting a point of view in which the present is defined in
terms of the events being analyzed. It is determined by our
interests rather than by our personal position in time. We may,
thus, have knowledge of the future of a particular event, and we
may and should consider its future as well as its past (1954, p.47).
Historical sequences do not have terminal points. To understand the
significance of Watt's engine is to place it in a series of events
that extend backward to sixteenth-century investigations into the
vacuum pump and forward towards the Corliss engine.
The Emergence of Novelty
The heart of the matter is how new things happen. By what
intellectual and social processes do new methods of production, new
products, and new patterns of behavior become objects of choice in
the stream of economic and social life?
Historians traditionally answered this question in two ways. The
first was that inventions are inspired intuition given to
exceptionally gifted persons. This approach stressed the
discontinuity of inventions and the importance of a small number of
inventors in creating the modern world. Usher deemed it
"transcendental," because in taking invention to be what amounts to a
miracle, it puts the event logically outside time, so that it can
have no mere historical explanation. The second approach took the
opposite tack of holding that inventions occur continuously in small
steps induced by the stress of necessity, somewhat like Darwinian
evolution.[8] Usher termed this approach "mechanistic," because it
relegated the inventor to the status of "an instrument or an
expression of cosmic forces."[9] Neither the transcendental nor the
mechanistic account of invention, then, was historical in the sense
that explanation necessarily takes the form of a narrative. To the
transcendentalist, inventions just happen (and we should all be
grateful they do); to the mechanist, they occur automatically in the
fullness of time. Neither explains _how_ inventions happen.
Invention is an event in the mind, so an empirically grounded model
of invention should be based on its cognitive properties. The
properties that Usher found most useful in this respect are drawn
from the findings of Gestalt psychology, which in the 1920s was a
thriving field of experimental research. Gestalt psychology proceeds
from the observation that the mind commonly perceives things as
wholes rather than as a chaotic flux of sensory stimuli. That
perception or gestalt, however, is not an ex post "interpretation" of
the stimuli; it is _how_ they are literally "seen," what Wittgenstein
called a "particular organization" of sensory (visual)
experience.[10] The physiological basis of this well-documented
phenomenon stems from evolutionary adaptations in neural circuitry
that enhanced the capacity of early hominids to quickly extract
signals from a perceptually noisy environment. As those adaptations
took place prior to acquisition of language, gestalt perception does
not obey the cognitive constraints of propositional logic embedded in
language, but conforms to the spatial logic of pictorial composition,
in where things take meaning from their "fit."[11] Because of this a
given stimulus can generate more than one true perception. For
example, in the classic "figure-ground" form, we may see a black
goblet against a white ground, or alternatively two white heads
staring at each other across a black field, but never both at the
same time. As the philosopher Russell Hansen put it, "There is more
to seeing than meets the eyeball."[12]
Usher contended that invention is seeing a "particular organization"
of data present in the inventor's mind. The gestalt paradigm opens
the door to an historical treatment of invention, because what we see
is influenced by our past experience, which is to say, our history.
Darwin confessed that he saw the "plainly scoured rocks, the perched
boulders, the lateral and terminal moraines" on his geological
rambles through the mountains of North Wales, but he did not see what
Agassiz had seen in Switzerland: that the eskers and eccentric
boulders were the product of glacial transportation. [13] What we
know limits what we are able to "see" at any point in time. That
constraint imparts directionality to discovery because in time we
come to know more things. But that directionality raises a further
question. What happens when we see something no one has ever seen
before, which by definition we do not know? In the figure-ground
experiment, could we recognize the goblet rather than the faces if we
had never before seen a goblet?[14] The inventor "sees" something no
one has ever seen before; it has no referent. What exactly does the
inventor recognize? What forces the data in his mind into a
"particular organization" that makes sense?
Usher proposed that the inventor "sees" a solution to the specific
problem occupying his mind at the instant of insight. The problem
serves as a focal point for organizing bits of information into a
pattern that potentially resolves it. Drawing on a graphical device
used by gestalt theorists to illustrate the "law of closure," Usher
compared the moment of insight to mentally arranging a set of broken
arcs into a circle, thereby satisfying the desire for completion
stimulated by the problem. The event is emotional, which accounts for
the common denial by cranks that their finding doesn't work. Looked
at in this way, invention is necessarily contextual, because in order
to be solved the problem has to be specific enough to support a
solution. When Watt was struck by the lightening bolt on Glasgow
green, he was not pondering the general problem of conservation of
heat; he was deliberating the concrete problem of its conservation in
a specific Newcomen engine.[15] That specificity puts dates on the
causal history of invention. Watt could not have posed his specific
problem the way he did before 1760 because an adequate quantitative
concept of heat had not yet been achieved. The balance cranes
invented by Brunelleschi to hoist materials for the dome of Florence
cathedral and that so impressed the young Leonardo solved the
specific problem of how to safely lift stone, brick and bronze
objects to the unprecedented height of 300 feet without knocking down
the walls of the building it rested on. The use of pullies and
counterweights goes back to antiquity; but their combination was
something new made possible by a more complete mathematical analysis
of the lever.[16]
In the instant of insight the elements of a potential solution to a
problem come into a new relation. Extrapolating from K�hler's
experiments on cognition in higher primates, Usher posited that the
elements must be actively present in the inventor's mind for insight
to occur. In the experiments, K�hler placed fruit just beyond a caged
ape's reach, placing a baton near the animal with which it could
capture the prized object. In repeated trials he found that the ape
solved her problem only when fruit and baton simultaneously lay
within her visual field; otherwise she remained baffled and
frustrated.[17] The experiment suggests that achieving a satisfactory
solution depends on serendipitous concatenation of its elements. That
condition imparts significant unpredictability to the achievement of
an invention, as nature rarely arranges the elements to in a form
revealing a satisfactory pattern.[18] There was a large measure of
luck in Edison's nervous fiddling with compressed lampblack while
reflecting on his frustrated efforts to find a satisfactory filament
for a light bulb.
Except in the rare instances in which inventors have left an
autobiographical account of their work, the historian can rarely
observe the actual moment of insight. What can be obtained from the
documentation are the problems that were posed and the presence or
absence of elements needed for their solution. This is usually enough
to construct an explanatory narrative. Usher noted that "even at a
level of incomplete verification, the historian can proceed to
develop the techniques of analysis that will reveal the grosser
features of the processes by which man makes himself." The invention
of printing provides a good, though complex example. The elements
needed to resolve the general problem of "mechanical writing"
included a suitable support (paper), suitable ink (oil-based), a
press (the woolen cloth calender) and moveable type. All of these
elements were available by the early fifteenth century, and were
being combined to make inexpensive wooden block prints by the 1430s
and 1440s. The general impediment to the using of this technique to
print books commercially was its inferior cost-effectiveness as
compared with that of books currently being produced in specialized
workshops by hand. The specific obstacle arose from the need to
produce type in large numbers, which meant casting metal pieces in
molds capable of holding matrices of variable size, and finding
suitable materials for the matrix and metal punches. To judge from an
incomplete documentation, the synthesis of the various elements that
solved this problem was a drawn-out affair lasting from the early
1440s to the 1470s, of which the decisive invention was the
adjustable type mold. The invention of printing was not the product
of a single mind or even a single firm, but can be seen as a
collective effort stretching over a whole generation. Its timing
seems to be dictated not so much by an overwhelming demand for
printed material, which until the price of books fell was satisfied
by the output of workshops, but by the convergence of independent
strands of technological know-how that suggested the possibility of
substituting machinery for men in making letters.
The gestalt experiments indicate that the process of invention is
strictly sequential, in that a problem must be adequately posed and
the materials for its solution assembled before insight can occur.
Usher identified a fourth stage in the process. Just as a new
scientific finding has to be integrated into the existing stock of
knowledge, so technological insight has to be translated into a
working model and scaled up (or down) to the size needed to perform
the desired task. Not every insight is workable. It took Watt nearly
a decade to transform his insight into a commercially viable steam
engine, and had it not been for the skills of Matthew Boulton's
machinists and Wilkinson's boring machine, the effort probably would
have failed. Usher termed that stage "critical revision." Like the
other stages, it consists of many acts of problem-solving.
Because of the necessary sequencing of its events, invention uses up
calendar time. At each stage problems arise that require to be solved
by insight, making the system inherently indeterminate. At best, the
historian can evaluate rough probabilities from objective constraints
imposed by the definition of the problem and the availability of
appropriate materials for its solution at a given point of time.
Usher stressed that because it is drawn out invention is by nature a
social process; nothing logically requires successive stages to be
achieved by a single individual or within a single epoch. The idea of
applying the principle of the Archimedean screw to propulsion of
vessels through water was first raised by a scientist in 1729, but it
took four decades of intense and expensive effort finally to bring
the screw propeller to fruition in the 1840s.[19] Usher regarded such
delays as the consequence of temporally definable "resistances." In
general, the resistances are not social or economic, but reflect
difficulties with respect to adequate formulation of the problem, the
absence of one or more of the essential elements to its solution,
failure to achieve the insight, and difficulties of its
implementation. All of these elements are in some measure subject to
verification, and thus narrated. Each makes invention time-consuming
and time-dependent.
Usher's approach also supplied the means to explain the history of
the economy. As noted above, optimizing adjustments by agents to
preferences and material constraints do not represent fundamental
change, because change comes ultimately from the introduction of
novelty into a social system. Usher situated that introduction in
man's capacity for problem-solving, thereby linking narrowly economic
history to the broader evolutionary history of mankind. That history
is not ruled by a timeless algorithm, but like the history of
biological evolution rests on specific events that can in principle
be identified.
[T]he act of insight does not rise above the contingency of our
knowledge upon specific contexts. Because these activities are
conditioned, analysis is possible; but because they are
conditioned they must be conceived as contingent upon the
relevant contexts. Acts of insight seek particular modes of
action or thought as a means of achieving specific ends. They
do not seek absolutes or eternal verities.
Problem-solving covers most spheres of life. Usher was particularly
interested in the technological sphere; but the general approach
applies to the more complex area of social problem-solving, of which
the construction of economic and social policy are the most important
examples. That history, however, is intrinsically more complicated
and harder to pin down than the history of invention. Like most
pragmatists of his day, Usher believed that the problems posed in
this sphere were largely created by the technological changes that he
regarded as having an autonomous history. They were not less
important, for all that, just more difficult
The Proof of the Pudding
A model is only as good as its implementation. Usher implemented his
model of invention through a chronological account of mechanical
invention in Europe from classical antiquity to the mid-twentieth
century. The selection of the mechanical band of the technological
spectrum was strategic, in that the decisive technological
breakthroughs driving falling transport costs and productivity growth
from the seventeenth through the mid-twentieth century were mainly
due to mechanization of operations previously carried out by hand and
the invention of new ways of generating power. It was strategic for
another reason: machines combine different techniques for
transmitting and controlling motion. A study focusing on the history
of specific syntheses held out the possibility of identifying the
circumstances that led to the combining of "the simple but relatively
inefficient mechanisms of early periods into the complex and more
effective mechanisms of today" (1929, p. 67). A final practical
reason was the comparative abundance of documentation.
The substantive chapters begin with a discussion of the difference
between scientific and technological knowledge. Until the seventeenth
century, science was, as it remains, an interpretation of the
physical world.[20] But outside celestial mechanics, where the
Ptolemaic system was used to calculate celestial positions, that
interpretation was either too broad to identify technological
opportunities, or too flawed to be of practical use. Drawing on
Pierre Duhem, Usher argued that the chief impediment to scientific
treatment of mechanics arose from the belief that the principles of
force and motion are self-evident. "Attention was thus drawn towards
logical demonstrations and mathematical theorems that involved pure
reasoning rather than towards experimental study of the phenomena."
Invention of devices for transmitting rotary motion and lifting heavy
objects thus rested on knowledge of the strength of materials
apprehended through practical experience, just as in ceramics and
metallurgy. It was only from the middle of the fifteenth century that
computational methods began to be applied to these problems, and it
was only from the middle of the seventeenth that they acquired the
power accurately to predict moments of force. From that point on,
progress in mathematical analysis of mechanical problems was rapid.
By the eighteenth century mathematicians and engineers were applying
Newton's third law of motion and Hooke's law of elasticity to
calculate the strength of materials, and using the embryonic science
of fluid mechanics to compute the pressure of water on water wheel
paddles and turbine blades.[21] Fulton's work on the application of
steam power to water craft is an outstanding example of this
work.[22] The contribution to invention was situated mainly in the
stage of critical revision.
The next chapter inventories the state of mechanical technology in
classical antiquity. Although classical scholarship has revised
Usher's understanding of draft animal harness, the diffusion of water
power, and the extent of geographical and occupational
specialization, his assessment of the possibilities for invention
remains sound.[23] At the end of the fourth century BC, classical
civilization knew the five basic machines: lever, pulley, wedge,
winch, and screw, and by the Christian era understood how gear trains
translate and transmit rotary motion. As noted above, scientific
analysis of these devices was not much help in designing new devices,
which meant that the opportunities to combine the elemental machines
into more complex devices depended on opportunities that manifested
in the more immediate perceptual field. The classical presses are a
good example: the beam press utilized pulleys to raise the weighted
beam, while the screw press combined beam and screw. These simple
combinations were closely tied to an immediate economic context
setting the problem to be solved. Thus, displacement of hand mill by
the rotary quern and the beam by the screw press to in the second
century BC responded to the immediate problem of efficiently meeting
the demand for large amounts of processed foods created by the growth
of cities and trade. One can see the same dynamic at work in the
invention of equipment for transporting and shaping exceedingly heavy
ornamental stones.[24]
The transition to greater input of conceptual knowledge in the
inventive process explains the tectonic shift in the complexity of
mechanical inventions between 1500 and 1700. Early machines
synthesized information obtained by visual and tactile perception
(and in the case of foods, by taste and smell). Such perceptual
insights are typically apprehended at low levels of generality and
have been achieved many times in many places. Parallel development of
lithic technology in the prehistoric world is explained by the
repeated discovery that siliceous stones flake predictably enough to
shape into useful forms.[25] The same was true of crafts based on
manipulation of physical materials. Getting beyond that immediate
level of insight, however, usually required the input of more
generalized knowledge. As machines grow more complex, the physical
and conceptual elements involved in achieving solutions to particular
problems multiply, but as general concepts in mechanics are not
immediately perceived by the senses, they are less likely to be
conceived, and thus culturally idiosyncratic.[26] At this point it
makes sense to compare concepts specific to civilizations as an
explanation of the divergence in technological development. Usher
regarded formulation of generalized scientific concepts as part of a
"round-about" process of invention, in which the problems addressed
are not immediately directed towards achieving a practical result.
Huygens analysis of the pendulum as a means of timing the escapement
mechanism in clocks is a good example.
Chapters 7 and 8 document the medieval history of two distinct
branches of mechanical invention dominated by the perceptual element.
The first harnessed the power of water and wind to mechanize the
operations of grinding, crushing, stamping, sawing and fulling; the
other captured the potential energy of gravitational force to drive
and time clockwork. Both developments worked out mechanical
principles mostly implicit in machines present in classical
antiquity. The development of water mills and wind mills is the best
documented, the critical element being the gear train translating
vertical rotation of the wheel to the horizontal plane of the
millstones. Gearing had been used in devices employed to measure
distance and angles, but its extension to heavy-duty work was
something new. One can imagine, but never demonstrate, that the idea
of the water mill was taken from the gear train utilized in the
cyclometer. Following an argument advanced by Lefebvre des No�ttes,
and since shown to be erroneous, Usher supposed that the diffusion of
water power was retarded by the deadening effect of slavery on
incentives to save labor. Archaeological evidence has since
demonstrated widespread diffusion of water-powered grain mills by the
second century AD, which speaks volumes to the value accorded to
economizing labor in the most burdensome tasks.[27] It also speaks to
the wide distribution of requisite carpentering skills. The smaller
horizontal and generally larger vertical mills diffused
simultaneously, their geographical distribution depending on the
nature of the stream and the economic advantage of high volume
milling. The increased incidence of vertical wheels after 1000 AD is
best explained not by technological innovation, but by opportunities
for scaling up milling operations created by the growing
commercialization of corn farming.[28]
Growing commercialization in the twelfth and thirteenth centuries
provided incentives to apply water power to other industrial
activities. The most important uses required translating the rotary
motion of the water wheel into reciprocal motion used to drive
bellows, stamping devices, and saws. Although Usher considered the
crank and cam to be medieval inventions, Ausonius's fourth-century
description of a water-powered device for sawing marble blocks in the
Rhineland indicates its presence in Antiquity. As in other areas, the
surviving documentation suffers from severe selection bias against
evidence for its early use. Gear trains were adapted to other power
sources where running water was unavailable or inconvenient. Of these
the most complicated mechanism was the gearing for the windmill,
which pivoted with the sail as it turned towards the wind. The most
revealing aspect of the windmill, however, illustrates how purely
perceptual knowledge produced inventions that achieved high levels of
technical efficiency. When Euler, MacLaurin and Coriolis undertook
mathematical and experimental studies of the optimal angle and shape
of windmill sails in the eighteenth and early nineteenth century,
they found that Dutch craftsmen had solved the problem as a practical
matter by the seventeenth century.[29] As in the case of the
watermill, the path of invention seems to have mainly reflected the
accretion of experience under conditions of expanding demand for the
apparatus.
Clockwork presents a different chronology. Timing devices controlled
by the flow of water through a self-regulating float valve were more
accurate than clocks whose timing was controlled by an escapement
mechanism and remained in use down to the eighteenth century because
they were cheaper to build and repair than the by then more accurate
mechanical clocks.[30] While the invention of the escapement
mechanism is obscure, its presence in clockwork is securely dated to
the third quarter of the thirteenth century. Subsequent development
of what was originally a massive mechanism exploited momentum of
weighted bars or wheels to time the escapement and damp the recoil.
Usher's discussion of these points is highly technical and directed
at questions of dating. In the broader history of mechanical
invention the importance of clockwork resulted from its complexity,
and demands for greater accuracy giving rise to a sequence of
problems that were gradually resolved by scientists and craftsmen of
the highest order. An important by-product of the construction of the
early tower clocks was the transfer of knowledge of how to cut and
design gears from the millwrights to blacksmiths. In the seventeenth
and eighteenth centuries the demand for greater accuracy created
opportunities to develop gear-cutting machines that gave solutions on
a small scale and for work in softer metals to problems that were to
emerge on a larger scale and in iron and steel.
The next chapter considers the place of Leonardo da Vinci in the
development of mechanical invention. Leonardo's role is both symbolic
and real. As a symbol he marks the shift towards scientific analysis
of mechanical problems (as an adult he taught himself geometry), and
the use of scale models to test the apparatus (a procedure pioneered
by Massacio to study pictorial composition). Of the 18,000 sheets he
bequeathed to his pupil Francesco Melzi, only 6,000 have survived,
and as they are not dated, it is impossible to determine the
representativeness of the sample and the sequence of his thought. He
invented a centrifugal pump, anti-friction roller bearings, a
screw-cutting machine, and a punch to make sequins for ladies'
dresses. He conceived a machine to make needles, and in 1514 was
given a room in the Vatican to construct a machine for grinding
parabolic mirrors to capture solar energy for boiling dyestuffs. He
expected to get rich from his inventions, and was alert to potential
opportunities to substitute machines for labor. He was not confident
in his Latin, and of Greek he had none. He sensed that mechanisms
were subject to common principles, but did not have the training to
bring the abstract concepts of force and movement into focus. His
workshop method of jotting down rough notes and cases was not suited
to sustained trains of abstract thought. But his capacity to imagine
three-dimensional mechanical connections, which his artistic training
permitted him visually to describe, was unequalled. His papers
circulated widely after his death, and provided ideas and inspiration
to inventors for nearly a century. Usher viewed Leonardo as embodying
the shift from perceptual to conceptual invention in the practical
sphere of mechanics.
Save for relatively isolated cases, mechanical innovation was
empirical, realistic, and practical. Achievements of great
consequence had been realized, but by a process in which the
immediate end was ever in the foreground. It is only with
Leonardo that the process of invention is lifted decisively into
the field of the imagination; it becomes a pursuit of the remote
ends that are suggested by the discoveries of physical science
and the consciously felt principles of mechanics (1954, p. 237).
The remainder of the book, with the exception of the chapter on
printing discussed above, traces out that subsequent history through
a chronology of the development of textile machinery, clocks and
watches, steam power, machine tools, and the development and
exploitation of the turbine. As these developments are well-known
there is no need here to review them here. In his account of
particular inventions, often in eye-glazing and occasionally
impenetrable detail, Usher was primarily concerned with showing the
cumulative nature of mechanical achievement, much of it by unknown or
relatively little known inventors. The development of textile
machinery provided a well-documented case in point. While the
increasing complexity of the material makes it difficult to reduce to
an intelligible story following the lines set out in his model of
invention, his broad conclusion was that the acceleration of
invention in textile machinery was conditioned more by the nature of
the mechanical difficulties to be overcome than economic factors. By
the early eighteenth century the technical capacity and craft skills
needed to overcome those difficulties were well in hand, as any visit
to a well-appointed museum of technology will demonstrate. From that
point on, progress depended on the way specific problems came to be
posed, or not posed, and how the stage was set for insight. By the
mid-eighteenth century, the increasing indirectness of invention and
its rising cost made securing and protecting intellectual property
rights increasingly important.
These factors are all evident in the development of the steam engine.
Caus's discovery that steam is evaporated water made it possible to
conceive the possibility of extracting power from atmospheric
pressure by condensing steam in a closed vessel. Exploitation of that
insight raised a series of technical problems associated with
positioning and controlling the valves regulating the flow of steam
and water. Watt's invention of the separate condenser was critical
revision of Newcomen's atmospheric engine. Translating that insight
into a commercially viable machine raised new problems the solution
of which largely depended on the skill and experience of Boulton's
craftsmen. The role of conditioning factors is illustrated by the
serendipitous appearance of Wilkinson's boring machine, which
machined a cylinder four feet in diameter to tolerances no thicker
than a dime. The development and diffusion of the steam engine in
turn led to greater use of metal gears connecting increasingly
powerful engines to increasingly heavy machinery, and as the speed
and force of the engines increased, the resulting stress and friction
induced intensive theoretical and practical study of the optimal
shape and position of toothed wheels and pinions. The sequence thus
illustrates Usher's general model of mechanical invention as a
sequence of problems raised and solved. We see in these developments
a comprehensible narrative of how one thing led to another in the
most critical region of the new technology.
The history of tools for shaping metal to high tolerances has a
parallel history. The basic elements of the mandrel lathe, slide rest
and lead screw were present by the end of the sixteenth century. In
the eighteenth century the wooden parts were replaced by metal,
increasing their accuracy and making it possible to machine heavier
pieces of metal. Senot's screw-cutting lathe (1795) displayed at the
Mus�e du Conservatoire des Arts et M�tiers is an outstanding example
of this development, and attests its international scope.[30] Usher
argued that after the substitution of iron for wooden headstocks, the
principal obstacle to the development of heavy-duty machine tools was
the difficulty of obtaining accurate lead screws. Here the problem
was well-specified, but achieving a solution required years of
painstaking work. Maudslay invented a device to correct errors of
one-sixteenth of an inch in a seven-foot screw, tested the result
with a micrometer, and made further corrections until he achieved the
desired result. Such accuracy was essential to achieve mass-produced
metal parts at low cost, though as Usher noted, the applications were
initially confined to narrow fields, most notably in the manufacture
of wooden pulley blocks, and firearms. Of more initial importance was
use of heavy machine tools to shape large pieces of metal to the fine
tolerances demanded by working parts of steam engines and
locomotives. By the middle of the nineteenth century that capacity
was available to be applied to a widening range of mass-consumed
products like agricultural equipment, sewing machines, typewriters
and bicycles. By that date the process by which specific mechanical
problems were posed, the stage set and critical revision of the
resulting insight carried out had become largely autonomous. It is
difficult to imagine what plausible reconfiguration of relative
factor endowments could have significantly affected the ensuing wave
of labor-saving innovation.
The final chapter sketches out the history of the turbine, of which
the applications range from more efficient exploitation of the power
in falling water to the exploitation of the energy in expanding steam
and gasses. Although it runs parallel to the development of the
reciprocal steam engine, the story of the contemporary development of
the turbine is a "particular system of events" that is entirely
distinct from it. As with machine tools, investigation of impulse
motors can be traced back to the early sixteenth century. The
technical problems to be resolved, however, were of the highest order
of difficulty, involving the invention of materials capable of
withstanding extremely high temperature and rotational friction,
finding optimal shapes and positions of the tubes and vans for the
different media that propelled them. All this took time. Mathematical
studies of turbulence relevant to the performance of turbines date to
the eighteenth century; the basic breakthroughs in design by
Fourneyron and Burdin date to the 1820s and 1830s. By the 1840s the
accuracy of machine tools was high enough to produce a tight fit
between the rotor and its casing. Parts rotating at ten to thirty
thousand rpm required grades of steel that became available only
towards the end of the nineteenth century; in the case of gas
turbines, the materials became available only in the 1930s. The
history of turbines, then, encapsulates the general trend in
mechanical invention from problem-solving directed at an immediate
solution with means assembled in the perceptual field to
problem-solving based on scientific analysis and assembly of
materials from a wide range of sources. The point is that all of this
took time, and although the rough outlines of a solution might be
fleetingly glimpsed, the timing of its achievement could not be
predicted. The first patent for a gas turbine was taken out in 1791;
a practical solution to the problem of exploiting the expansive power
of heated gas in jet engines was achieved only in the 1930s.
The development of the turbine leads the discussion to the generation
and transmission of electric power. The potential of large heads of
water and great heads of steam could not be exploited as long as it
had to be employed in situ, because no establishment could take more
than a small proportion of the total power available. The invention
of the dynamo and means of long-distance transmission relieved that
constraint. The early development of that technology was achieved
between 1830 and 1880, by which time the crucial problems had been
resolved. That history, too, represents a particular system of
events. The history of internal combustion engines illustrates the
same pattern. An early recognition of the possibility of using the
explosive power of gas in a piston (Huygens, 1680, Papin, 1690),
followed a century later by patented engines (Street, 1794; Lebon
(1799), lack of success for an extended period of time due to the
inaccuracy of machining, difficulties of controlling the timing of
the ignition and opening and closing of the valves, followed by a
successful inefficient engine leading to closer analysis of the
sources of that inefficiency. The sequence plays itself out as a
narrative. Usher observed that from a broad perspective the history
of the individual sources of power revealed a tendency to develop all
possible forms of application of a general principle. The result was
that by 1950 the world possessed a set of power-generating devices
that spanned the gamut of weight and power capacity.
The _History_ ends with that observation. Over the course of more
than 300 pages of substantive discussion, it gives an overview of the
development of what was the central strand of technological
development through the early twentieth century. It explains within
the limitations of the documentation and the level of detail
appropriate to a general overview how novelty emerged in the sphere
of mechanization and the generation of power. Usher offered no
conclusion to this work. Indeed, in the introduction to the second
edition he noted that he deliberately avoided forcing the narrative
into a preconceived mold. The _History_ was not a test of the theory
of emergent novelty, only an illustration. In his later work Usher
returned to the question of how to combine the insights of economics
with an empirical treatment of time. He argued that "any consistently
empirical interpretation of history must find some adequate
explanation of the processes of change."[32] The great enemy to a
rational understanding of the past in his time, as in ours, was
radical idealism, which seeks to explain events by their presumed
final ends or purpose.
Usher's work raises a number of problems that have been imperfectly
addressed. His insights on the nature of mechanical invention are
generally accepted and have been extended by historians of technology
and economic historians, but the model has not been generally applied
to other spheres.[33] A significant obstacle to its implementation is
the extremely high degree of technical detail required to give an
adequate account of any particular technological development. While
detail at that level is common in the fields of political and
institutional history, the desire to read such accounts is an
acquired taste, though perhaps no more so than in the arcane corners
of art history. As a consequence, the deployment of Usher's method by
economic historians has tended to be illustrative rather than
narrative and probative. The rhetorical difficulties turn on the
audience to be addressed, and the level of generality required by the
narrative. On the broader question of the role of time in economic
processes, the picture is equally discouraging. The debate over the
nature and significance of path-dependence touched analytical issues
raised by Usher, but it was deflected by questions relating to
dynamic optimality, which as Usher had anticipated, originate in a
transcendentalist obsession with final ends. As a result, the
question of what happened and how it happened got pushed aside by the
question _why_ it happened. "Why" questions are intrinsically
non-empirical.
Usher's focus on explaining the emergence of novelty as the special
province of economic historians is nevertheless worth preserving.
Bill Parker organized his lectures on economic history around the
framework of challenge and response, which is just a broader way of
identifying the history as a history of problems posed and resolved
(or not). The problems are not just technological. The analysis of
organizational and political responses to economic change can be
carried out on lines similar to those that Usher considered workable
for the study of scientific and mechanical invention. Some responses
are comparatively easy to model using standard tools derived from the
calculus of optimization; others require more contextual detail. A
workable history, however, requires limiting the field to a
"particular system of events" that permits a narrative account. An
outstanding example of this type of economic history is Wright's
account of American slavery.[34] Since the early 1960s the main
thrust of economic history was directed away from Usher's concept of
explanation by narration. The power of Kuznets' categories to
organize numerical data provided nearly two generations of economic
historians with productive work filling in the gaps and running down
the tangled chains of quantifiable explanation. But Kuznets took the
technological revolution as a given; the modern economic epoch was
its consequence. Yet in the end, to quote one of the less illustrious
figures in American history, "stuff happens." Part of the task of
economic history is to find out exactly what that stuff was, and how
it happened. Usher's work is a model of that type of economic
history, and also shows how difficult it is to successfully pull off.
Postscript
I was distractedly browsing through my alumni bulletin this evening
-- checking the latest mortalities and other alumni affairs -- when I
came across the following passage in an article on Leland C. Clark
(Antioch College 1941), who received the Frit J. and Dolores H. Russ
Prize (the nation's stop award for scientific engineering) in 2005
shortly before his death.
Here's the story of his oxygen electrode invention.
Late one night, Clark -- then in his thirties -- was opening a
pack of cigarettes while relaxing with colleagues after
assisting in a by-pass surgery using his prototype heart-lung
machine. Although the surgery had been successful, Clark knew
that such procedures require precise monitoring of oxygen levels
in the blood. But the platinum electrode he had originally
designed wasn't working well; red blood cells were blocking the
oxygen molecules near the electrode.
What happened next was one of many shining moments in Clark's
career. "He was fiddling with his cigarette pack and suddenly
got the idea that oxygen might permeate cellophane." Soon
thereafter, Clark tried moving the two electrodes close
together, protected inside a glass tube by a cellophane
membrane. The innovation allowed oxygen to enter and be
measured with no interference from the red blood cells. To
test the new oxygen sensor he needed to find a way to pull the
oxygen out of a control solution to calibrate the sensor settings.
He added glucose and the enzyme glucose oxydase, as a catalyst,
and the oxygen was quickly removed.
Before long, however, he realized that by equipping his
oxygen sensor with a thin film of the enzyme, he could read the
decrease in the oxygen recorded in the presence of glucose.
Suddenly Clark had a simple device for measuring glucose,
also inventing the first biosensor for that purpose. Today,
electrochemical biosensors have been designed to measure
lactate, cholesterol, lactose, sucrose, ethanol and many
other compounds.[35]
One sees here all of Usher's stages in exceptional relief: the posing
of the problem, the setting of the stage, the insight and critical
revision, followed by extension into new problems and new solutions.
Notes:
1. Perhaps no better example of that vision can be found than in
following passage composed by the aged Friedrich Meinecke in its
wreckage. "Behind the growing pressure of increased masses of
population ... stands the struggle for the way of life of the
individual nations. By way of life we mean here the totality of the
mental and material habits of life, the institutions, customs and way
of thinking. All of these seem to be bound together by an inner tie,
by some guiding principle from within, to form a large, not always
clearly definable but intuitively understandable, unity." _The German
Catastrophe: Reflections and Recollections_. Boston (1950), p. 87.
2. Erik Grimmer-Solem, _The Rise of Historical Economics and Social
Reform in Germany, 1864-1894_, Oxford (2001).
3. T. H. Marshall, _English Historical Review_ 42 (1927), 624.
4. "The Application of the Quantitative Method to Economic History,"
_Journal of Political Economy_ 40 (1932), 186-209.
5. Cited by Veyne, _Writing History: Essay on Epistemology_,
Middletown, CT (1984), 119.
6. Veyne, _Writing History_, 63
7. Veyne, _Writing History_, 26-27. The literary reference is to
Balzac's _Grandeur et d�cadence de C�sar Birotteau_.
8. Mokyr appears to adopt this perspective in his evolutionary
interpretation of technological change. "Like mutations, new ideas,
it is argued, occur blindly. Some cultural, scientific, or
technological ideas catch on because in some way they suit the needs
of society, in much the same way as some mutations are retained by
natural selection for perpetuation. In its simplest form, the
selection process works because the best adapted phenotypes are also
the ones that multiply the fastest." _The Lever of Riches_, New York
(1990), 276. The proposition is defensible with respect to economic
factors conditioning the diffusion of inventions. It does not
explain, as Usher surely would have observed, _how_ inventions
happen. Mokyr's concept of a unit technique or idea subject to
selection bears an obvious resemblance to Leibniz's monad, and the
sufficient reason that generates in the fullness of time the "best of
all possible worlds."
9. Explaining technological change by Malthusian population pressure
is an example of this kind of approach. For a recent example, see
Oded Galor and David Weil, "Population, Technology and Growth,"
_American Economic Review_ 90 (2000), 806-28.
10. Ludwig Wittgenstein, _Philosophical Investigations_, Oxford (1972), 196.
11. See Norbert Russell Hanson, _Perception and Discovery_, Cambridge
(1958), and more generally Wittgenstein, _Philosophical
Investigations_.
12. Hanson, _Patterns of Discovery_, 7. A celebrated instance of dual
perception was the inability of researchers to identify the cause of
the potato blight, in which the fungus _Phytophthorus infenstans_ was
alternatively believed to be a cause and consequence of the disease.
13. _The Autobiography of Charles Darwin_z edited by Francis Darwin,
New York: Dover Publications (1958)z 26.
14. Locke reports a conjecture made to him by a French correspondent
who suggested a man cured of blindness might not be able to
distinguish between a box and a sphere. That conjecture has been
experimentally confirmed.
15. "I was thinking of the engine at the time, ... when the idea came
into my mind that as steam was an elastic body it would rush into a
vacuum and might there be condensed without cooling the cylinder"
(cited in Usher (1954; 71)).
16. Salvatore di Pasquale, "Leonardo, Brunelleschi, and the Machinery
of the Construction Site," in Montreal Museum of Fine Arts, _Leonardo
da Vinci: Engineer and Architect_, Montreal (1987), 163-81.
17. In another set of experiments with chickens food was placed
outside a rectangular enclosure having an opening on one side. The
hens "solved" the problem of obtaining the food only when the food
and the doorway were in their line of sight.
18. The one major exception may be the "invention" of agriculture in
the Near East, which most likely occurred through an improbable
sequence of climatic changes that induced incipient domestication in
a handful of small grains and pulses harvested in naturally occurring
stands. The term invention is inappropriate in this context. See
David Rindos, _The Origins of Agriculture: An Evolutionary
Perspective_, Orlando FL: Academic Press (1984), and Donald O. Henry,
_From Foraging to Agriculture: The Levant at the End of the Ice Age_,
Philadelphia: University of Pennsylvania Press (1985).
19. The chief obstacles were intellectual, one being disbelief that a
device as small as a propeller could drive a large ship, and the
other concerning the optimal shape of the device in the context of
extremely complex issues with respect to fluid mechanics. The history
is reviewed by Maurice Daumas, ed., _A History of Technology and
Invention, Vol. 2_, New York (1972).
20. Prior to the seventeenth century it also interpreted the
non-physical world, as the medieval enquiry into the physics of the
Eucharist amply demonstrates. On this and other topics relevant to
the present discussion, see Edith D. Sylla, _The Oxford Calculators
and the Mathematics of Motion, 1320-1350_, New York (1991).
21. Maurice Daumas, ed., _A History of Technology and Invention,
Volume III_, New York (1979), 25-27, 81-89.
22. Fulton made countless experiments calculating the resistance to
paddlewheels of varying design and to the form of the hull in
relation to the weight and velocity of the engine. His work was based
on Colonel Mark Beaufoy's experiments testing Euler's theorems on the
resistance of fluids. This was critical revision. H. W. Dickson,
_Robert Fulton: Engineer and Artist_, London (1913).
23. See my manuscript, "Prehistoric Origins of European Economic Integration."
24. J.B. Ward-Perkins, "Quarries and Stone-working in the early
Middle Ages: The Heritage of the Ancient World," _Artigiano e tecnica
nella societ� dell'alto medioevo_, Spoleto (1971), 525-44; Valery A.
Maxfeld, _Stone Quarrying in the Eastern Desert with Particular
Reference to Mons Claudianus and Mons Porphyrites_, in David
Mattingly and John Salmon, eds., _Economies Beyond Agriculture in the
Classical World_, London (1991), 143-70.
25. Brian Cotterell and Johan Kamminga, _Mechanics of Pre-industrial
Technology_, Cambridge (1991), 127-30.
26. Within restricted ranges of perception many mechanical concepts
are indistinguishable. Where friction is present, the Aristotelian
theory that constant force is needed to keep an object in uniform
motion is observationally equivalent to Newton's principle of inertia.
27. The archaeological evidence, which was not available to Usher, is
abundant. For a compilation of European finds, see Orjan Wikander,
"Archaeological Evidence for Early Watermills: An Interim Report,"
_History of Technology_ (1985), 151-79, and Richard Holt, _The Mills
of Medieval England_, Oxford (1988). North African evidence is
surveyed by David Mattingly and R. Bruce Hitchner, "Roman Africa: An
Archaeological Review," _Journal of Roman Studies_ (1985), 165-213.
28. A similar transformation around the same time can be seen in the
substitution in northern France of naked wheat (triticum aestivum)
for spelt (triticum spelta), which being a bearded cereal costly to
transport and difficult to mill was less suited to commerce. The
displacement and the appearance of the vertical mill went hand in
hand. See Jean-Pierre Devroey, "Entre Loire et Rhin: Les fluctuations
du terroir de l'agriculture au moyen �ge," in J.-P. Devroey and J.-J.
van Mol, _L'�peautre (triticum spelta): Histoire et ethnologie_,
Bruxelles (1989), 89-105.
29. Daumas, _History of Technology and Invention, Volume III_, 20-22.
30. Galileo used water clocks in his experiments on falling objects.
31. Maudslay's all-metal bar lathe is dated to the same year.
32. Usher, "The Significance of Modern Empiricism for History and
Economics," _Journal of Economic History_ (1949), 149.
33. I made a preliminary stab in "The Shifting Locus of Agricultural
Innovation in Nineteenth-century Europe: The Case of the Agricultural
Experiment Stations," in Gary Saxonhouse and Gavin Wright, eds.,
_Technique, Spirit and Form in the Making of the Modern Economies:
Essays in Honor of William N. Parker_, _Research in Economic History,
Supplement 3_, Greenwich, CT (1984), 91 214.
34. Gavin Wright, _Slavery and American Economic Development_, Baton
Rouge (2006).
35. "Leland C. Clark Leaves a Medical Legacy," _Antiochian_ (Autumn 2006), 31.
George Grantham teaches economics and economic history at McGill
University. He is the author of several works on the productivity of
French agriculture in the nineteenth century, the macroeconomics of
pre-modern agricultural societies, and the economic history of
prehistoric Europe. He is presently applying Usher's concept of a
"particular system of events" to reconstruct the pre-modern history
of European agricultural productivity.
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