This paper investigates postmortem timestamp reconstruction in environmental monitoring networks. In the absence of a timesynchronization protocol, these networks use multiple pairs of (local, global) timestamps to retroactively estimate the motes’ clock drift and offset and thus reconstruct the measurement time series. We present Sundial, a novel offline algorithm for reconstructing global tim...

The ancient art of sundial designing and making has produced an astonishing variety of designs, many of them ingenious and works of art. The history and a fair sample of various designs can be found in [Ro] or [Pe,Sch,SP]. The principles of working are in many cases forgotten and understood only by a very tedious reverse-engineering, often made much more difficult by wellmeant but incompetent r...

Robert Hooke is commonly thought of as the inventor of ‘Hooke’s joint’ or the ‘universal joint’. However, it is shown that this flexible coupling (based on a four-armed cross pivoted between semicircular yokes attached to two shafts) was in fact known long before Hooke’s time but was always assumed to give an output exactly matching that of the input shaft. Hooke carefully measured the relative...