Created 7/10/1997
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David Landes on the Chinese State and Technology

From David S. Landes, Revolution in Time (Cambridge: Harvard University Press, 1983).

In the year 1086 of our era, the boy emperor of China, or more probably his ministers, ordered an examination of the astronomical devices inherited from previous reigns and the construction of an astronomical clock that should surpass anytht had been built before. He chose for this task a certain Su Sung, an experienced diplomat and administrator with scientific interests. Su Sung gathered a team of officials, technicians, and craftsmen, naming as designer and superintendent of construction a certain Han Kung-lien, then "a minor official in the Ministry of Personnel." (In china there was no horological profession, and talent was to be found in unexpected places.) Two years later a working wooden model was finished; two years more, and the metal parts of the great clock were cast in bronze; four more years (1094) and the "explanatory monograph" was ready for presentation to the emperor, and presumably the clock with it.

Su Sung's clock... was one of the marvels of the age. It was designed to reproduce the movements of the "three luminaries"--sun, moon, and (selected) stars--which were crucial to Chinese calendrical calculation and astrological divination. It did this by means of an observational armillary sphere--that is, an assemblage of rings representing the paths of these bodies as they presented themselves to an observer on earth--and a demonstrational celestial globe, each rotating on a polar axis and appropriately inclined to the horizon.... The whole mechanism, which must have weighed tons and occupied a tower about forty feet high, was powered by a water wheel designed to turn intermittently at a stable rate....

...Why did science originate in Europe and not in China, which seemed so much readier for it? The question is the more pertinent because horology is only one of several areas in which the technology of medieval China was ahead of that of Europe: it was China, after all, that gave us paper, gunpowder, movable type, porcelain, and other important and ingenious topics. Recall in this regard the wonderment of Marco Polo, who was no country bumpkin but a citizen of Europe's greatest trading city....

... On balance... there seems every reason to believe that the Su Sung clock could perform well on a day-to-day basis--certainly far better than the early mechanical clocks that made their appearance in Europe almost two hundred years later. How it did over longer periods, we do not know.... The model of the Su Sung clock nonw standing in the Time Museum in Rockford has not kept a stable rate, partly for mechanical reasons, partly perhaps as a result of temperature problems.

It is probably this difference between short run and long that accounts for the contradictory reports that have come down to us. The Chinese boasted of their peak performances, yet also commemorated their failures. The records seem to show that none of their great clocks kept good time over a long period; indeed, none of them lasted. The annalists report these disappointments in matter-of-fact declarative prose--reflecting perhaps the Chinese temperament and good annalistic manners, but also the functional reality.

Given the calendrical-astrological objectives of these clockwork astraria, an accurate rate was desirable but not necessary... What does it matter if the timing of the winter solstice is off by an hour, several hours, or even a day? A great deal in principle; indeed, the very legitimacy of the emperor rested on the harmony of his decisions and actions with the patterns of the cosmos. In practice, though, there was room for error, so long as it was not patent. If the astronomers found an anomaly, the armillary sphere could be adjusted and the calendar corrected. The important thing was the appearance of knowledge, duly certified to the ruler by the court astronomers and proclaimed by him to the people.

The criterion, in other words, was political rather than scientific. The astronomers understood that only too well: we are told that in the tenth century the representatives of the two imperial observatories, which were supposed to arrive at results independently and check them against each other, used to compare and reconcile their data in advance. They did not even bother to use their instruments to make observations, but rather copied out the positions from the tables of ephemerides. "Everyone knew about it, yet no one thought it strange."

One hundred years later this collusion was still taking place. When the new astronomer-imperial learned of , he had some of the astronomers exposed and punished, but to no avail: "The deceptions continued as before."

Su Sung himself ran into this problem in the course of his diplomatic career. He was charged with an embassy to the Liao kingdom in the north.... His task was to bring a gift to the Liao emperor, whose birhday chanced to fall on the winter solstice. But the Chinese calendar had the winter solstice a day early, so that when Su Sung brought his gift to the Liao court, the officials were at first unwilling to accpet it. This is the story as the Chinese memorialist Yeh Meng-te (c. 1130) tells it:

As the barbarians had no restrictions on astronomical and calendrical study, their experts in these subjects were generally better, and in fact their calendar was correct.... Of course Su Sung was unable to accept it, but he calmly engaged in wide-ranging discussion on calendrical science, quoting many authorities, which puzzled the barbarians who all listened with surprise and appreciation. Finally he said that after all the discrepancy was a small matter, for a difference of only a quarter of an hour would make a difference of one day if the solstice occurred around midnight.... The barbarians had no answer to this, so he was allowed to carry out his mission. But when he returned home he reported to the Emperor Shen Tsung, who was very pleased at his success and at once asked which of the calendars was right. Su Sung told him the truth, with the result that the officials of the astronomical bureau were all punished and fined.

Consider now the implications of the Yeh Meng-te account. "The barbarians," he writes, "had no restrictions on astronomical and calendrical study"; hence, "their experts in these subjects were generally better" than the Chinese--this, mind you, without the help of wonder clocks. In China the calendar was a perquisite of sovereignty, like the right to mint coins. Knowledge of the right time and season was power, for it was this knowledge that governed both the acts of everyday life and decisions of state. Each emperor inaugurated his reign with the promulgation of this calendar, often different from the one that had preceded it. His court astronomers were the only persons who were permitted in principle to use timekeeping and astronomical instruments or to engage in astronomical study. His time was China's time.

In effect, this was a reserved and secret domain. There was no marketplace of ideas, no diffusion or exchange of knowledge, no continuing and growing pool of skills or information--hence a very uneven transmission of knowledge from one generation to the next.... Under the circumstances we can understand the repeated lapse of knowledge over long periods, so that each great clockmaker had to search in old records for the forgotten secrets of earlier reigns.... These were not stupid people--they just did not make astronomical clocks very often....

One last comment about the annalis's account of Su Sung's mission; he writes that Su Sung... "clamly engaged in wide-ranging discussions on calendrical science, quoting many authorities, which puzzled the barbarians..."... Now it is hard to say... what exactly puzzled the so-called barbarians, but one thing that may have puzzled them was the recourse to authority rather than to evidence. Reference to authority may have been decisive in the monopolistic astronomy of China; it was no doubt less effective in a competitive, emulatory context; and it must surely have inhibited curiosity, originality, and observation.

It also promoted the corruption of science by factional politics. A memorial by court official Wang Fu written only a generation after Su Sung, at a time when Su Sung's clock was presumably still working, treats the subject of astronomical water clocks without any mention of Su Sung. [Joseph] Needham suggests that partisanship is the explanation: "Su Sung's clockwork was associated with the Confucian Conservatives--Wang Fu was one of the Taoistic Reformers." When these came to power in 1094, a "committee of investigatin" was established to scrutinize the court's astronomical instruments, and the very existence of Su Sung's clock was placed in jeopardy.

Is that the way to run an observatory?

Is that the way to treat a clock?

Also see the abjuration of Galileo.


Created 7/10/1997
Go to Brad DeLong's Home Page

Professor of Economics J. Bradford DeLong, 601 Evans, #3880
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