Program—And then it drops: On Suspended Sensing
Think — Essays | May 2013

And then it drops: On Suspended Sensing
By Natasha Ginwala

In 132 AD, long before seismic events were codified within the discipline of seismology, a sensitive instrument was invented in the Chinese Eastern Han dynasty (AD 25–220) to read the directionality of earthquakes. Its inventor, Zhang Heng, was a renowned polymath: distinguished cartographer, mathematician, painter, and writer-poet, educated in the moral and political philosophy of Confucianism, who held a number of official positions within the Han dynasty court. His ingenious seismoscope[ref] Zhang Heng’s seismoscope has raised curiosity across the world for centuries, with attempts at recreation undertaken across China, Japan, and North America.[/ref]—commonly referred to as the “Dragon Jar”—found mention in the Book of Later Han as a tool integral for Emperor Shun’s rein. Without surviving material remains, it is a device that now mainly exists as an ‘unproven document’ within a biography. Its ‘real’ effect in the contemporary world is hence that of an imaginative proposal which once influenced the administrative life of an empire. And, considering that natural disasters can never truly be calibrated or masterminded, it is somehow fitting that a tool invented towards a greater understanding of earth’s inner layers has also gone missing in the sediment of history, performing as a phantom within contemporaneity’s exercises in permanent re-construction.

Zhang Heng’s earthquake instrument stands as an anticipatory vessel. The eight toads at its base reach backwards with their mouths gaping open, waiting. Corresponding dragonheads, oriented to the eight cardinal points, emerge from the girth of the bronze vessel, each bearing in its jaws a single bronze sphere. The water-filled jar would act as an amplifier of subtle vibrations in the ground’s surface, upsetting an inverted pendulum and producing a lateral displacement that triggered the release of one of the bronze balls. As the ball drops, and as it reaches one of these toads, a ringing tone is emitted. The toad is a bell that becomes an alarm; in this, the instrument stands doubled as both seismoscope and seismophone. The earthquake instrument anticipates not only a seismic signal, registering disaster for a nearby human settlement, but also a kind of geo-cosmological feedback.

Reconstruction of Zhang Hengs seismoscope by Wang Zhen-duo, 1963.

The image above is among the many retrospective speculative diagrams and study models of the so-called Dragon Jar. Yet, it is also one of the most credible propositions to date, developed in 1963 by the Chinese scholar Wang Zhen-duo. Significantly, it reveals the inner-workings of the instrument that captured the attention of so many for so long. This diagrammatic study renders a multi-temporal depiction condensing ‘before’ and ‘after’, with the translucent pendulum marked as a phantom. The loosed bronze ball is falling, as it is also suspended; neither positioned as a before nor an after but between the two.

The information received by the Dragon Jar was available in interpretation as heavenly guidance for state affairs. Its name, “Heonfeng didong yi,” translates literally as, “Instrument measuring seasonal winds and movements of the earth.” This refers to the Eastern Han dynasty’s understanding of winds as both oracles and the cause of earthquakes. The instrument bears this cosmological narrative in its morphology, with the dragons symbolic of sky and the toads symbolic of earth. In real terms, the accuracy of Heng’s earthquake instrument translated to political advancement within the court hierarchy, along with a substantial rise in his riches and influence. In the last years of service under the emperor, Heng was promoted as a closer advisor and governor chiefly in charge of administering river channels. As a tool, the Dragon Jar was thus an instrument of power calibrated to enhance the Emperor’s rein through a specially permitted (over)hearing of earth-messages.

The instrument may accordingly be viewed as enmeshed within cosmological and political configurations. Here, its registration of directionality can be seen to produce positionality; the index of a geographical and political centre. It calls to mind the maps of the Qing dynasty, over one and a half thousand years later, in which the emperor’s travel route is marked as a perfect horizontal line and all geography is brought to wrap around this course (two wonderful examples of these are exhibited within the Taiwan Palace Museum). The question arises, then, for whom the bell rang; of who was permitted to overhear its message of the earth’s movement, and of the speculative cryptography of its decoding.

The Dragon Jar once recorded an earthquake that was not reported in the court until several days later. It was initially thought the Dragon Jar had caused a ‘false alarm’. Could it still be trusted? Several days later, news arrived reporting an earthquake in the Longxi county of Northwest China—between the Tibetan plateau and borders of Mongolia. During this interim phase of ‘not-knowing’, a course of action remained unclear, emanating as a structural gap in time. Following the Long Xi earthquake, the emperor ordered his official historian to register every recording of Heng’s seismoscope as the final witness. The transferral of the metal ball from the jaws of the dragon into the gut of the frog became the ultimate verification that an earthquake had indeed ‘taken place.’

Like many fictions surrounding the Dragon Jar, this is just another story, and yet it is a relevant basis to consider how to locate the specificity of trust when it comes to seismic events—is it the device, the expert, or the travelling messenger who is ultimately a reliable reporter of an earthquake’s occurrence? The point at which verification is located among these agents produces a political distribution of trust and truth that privileges some ears above others. This begs also what hearing is preferred through present-day configurations of trust in tools of information and of their concurrent systems of governance through remotely accessed knowing.

In parallel with Zhang Heng’s interest in literature grew a passion for astrology. When he became chief of the royal observatory, apart from studying astronomical phenomena, time devices, and calendar systems, he also invented machines such as the armillary sphere—a celestial globe that was also a clepsydra (water clock). It rotated accurately once a day and was inlaid with over a thousand stars that showed the ecliptic and the equator. His book Ling Xian (AD 120) is a treatise on the evolution of the earth and cosmological structures, including theories on planetary movements as well as the lunar eclipse. Heng’s investigations into the cyclicality of time brought about a holistic view on the phenomena of tectonic movement, depicting it as material directionality—a force from within the earth—, represented through a mirrored echo of physical trembling within the instrument of measure. The Dragon Jar is a narrative scenography, with the dragons and the toads as lead protagonists enabling a gestural scripting of the earth’s inner conditions. The violence of ‘nature’ is here not conceived as ‘senseless devastation’ but is, instead, the measurable variability of geological orientations and particle motions resonating through the pendulum of the instrument-body.

In contrast to the present-day Richter Scale, Heng’s device contends that ‘magnitude’ is not something traceable to a visual diagram of frequencies registered as wave-forms—its sensibility lies elsewhere, as a narrative of suspicion in material suspension. Rather than anthropomorphizing the earth, such that its persona is ‘read’ like a heart rate monitor, Heng remained invested in ‘seeing’ tectonic movements through changes in the degree of rhythm, motion, and time. Equally radical were the claims of Althanasius Kircher, who understood that as a living form the subterranean world is a series of discontinuities and molten excesses,“the whole Earth is not solid but everywhere gaping, and hollowed with empty rooms and spaces, and hidden burrows,” he said.[ref]Athanasius Kircher, Mundus Subterraneus (1665).[/ref]

The unit of notation in Heng’s instrument was a bronze sphere, a ball. And perhaps it is not coincidental that among Heng’s contributions to mathematics was a refined numeration of pi. In their situation of suspension, the eight balls are the units upon which the anticipatory weight of the instrument comes to bear. It is the loosened ball that, upon landing in the awaiting belly of a toad, produces the ring, and finally marks the registered direction.

Stepping away from the instrument body, the artist Pratchaya Phintong is interested in the Dragon Jar’s logic of instrumentalization. It is the notational unit of the ball that he hones in on in his work One of them (2012). Working with an artisan in Beijing, Phinthong produced two black, craggy spheres made of Ytrium, a rare earth metal used in present-day electronic seismometers.

At the time that Phinthong produced One of them the leadership of China, which controls 97% of global production in rare earth metals, had announced that it would reduce its international supply by 70%. These metals are crucial to high technology devices for sensing, computing, geo-location, and memory as used in both domestic technology and advanced weaponry. This threatened suspension in the transfer of such earth substances upset political interests and balances with the Obama administration, which registered its protest with the World Trade Organization.

The terms of knowability and predictability hold a spectral place for Heng’s seismoscope. In making One of them, Pinthong produced only two of what could have been anticipated as eight spheres of Yttrium, pointing to the status of only partially knowing. The problem of predictability in seismic knowledge, that is its lack, stands also as an index of these limits of knowing.

In a gesture of knowing through material acting that similarly enunciates its own limits, the English seismologist John Milne reconstructed the external design of Heng’s seismoscope in 1883. While his construction was not fully functional, Milne was the first to identify that the Dragon Jar and other modern seismographs are based on the principle of inertia. As the force of the trembling earth meets the velocity of the metal ball released from the dragon, we begin to understand its inner dimensions of resistance in object-terms—that the earth itself is a field in momentum. The withholding of rare earth minerals becomes another mode of resistance—the ‘unpredictable’ momentum of game changing political mobilization. Ultimately, as a ‘lost’ proposition, the Dragon Jar has remained an extremely useful model in furthering the discipline of seismology itself, less as a field of answerability and more as a question of the earth’s readability through a gestural ‘falling into’.

Natasha Ginwala and Vivian Ziherl

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