The accuracy of scientific observation and calculations always depends on the scientist's timekeeping methods.科学观测及计算的精度总是取决于科学家的计时方法。
The steelyard clepsydra, a special type of clepsydra, had been the chief timekeeping instrument during the Sui-Tang period and the earlier stage of the Northern Song dynasty.摘要秤漏是一种特殊类型的漏刻，在隋唐及北宋前期曾是司天机构的主要计时仪器。
