the equal distance of a second of a degree from each other, just as one sees the surface of large maps traced by meridians, nearly thirty of those lines would then have been covered in by the east and west span of the crystal roof.  Mr Dent’s clock might have been set to the precise time of the Greek Slave, and it would yet have been nearly two seconds wrong by the time of the Liverpool Model.  The pendulum swinging so steadily within its case had a longer and more stately stride than most of its congeners.  It took a second and a half of time to complete its step from side to side.  But notwithstanding this, if a string had been suddenly stretched across in space above the east end of the building, and left there in free suspension, independent of all connection with the terrestrial surface, it would have taken longer for the huge structure to be trailed beneath it by the earth’s rotation—­swift as that rotation is—­than it did for the sober and leisurely mass of metal to finish its beat from side to side.

Our immediate business, however, at this present time is not with the geographical relations of Mr Paxton’s building, but rather with that sober and leisurely-moving mass—­the pendulum.  Even in the seventeenth century, old Graunt was shocked when some irreverent babbler spoke of one of its honourable race by the rude epithet of ‘a swing-swang;’ and he penned an indignant protest on the subject to the Royal Society.  Since that time the pendulum has done much more to merit the reverence of the world.  Plain and simple as its outward bearing is, it really holds a high and dignified position in the annals of science.

Instead, however, of touching upon its pedigree and achievements, we proceed at once to speak of certain interesting peculiarities that enter as an element into all considerations in which it has concern.  In the first place, what is that characteristic motion which it so constantly assumes—­that restless swinging from side to side?  Is it a property inherent in its own nature, or is it a power communicated to it from without?  There is a train of wheelwork enclosed with it in the case.  Is that the source of its vibratile mobility?  Assuredly not.  For if we arrest its motion with our hand at the instant that its form hangs perpendicularly suspended, that motion is not renewed although the wheels remain in unaltered relation.  Those mechanical contrivances clearly do not comprise the secret of its swinging.  We must look elsewhere if we would ascertain the fundamental cause.

Has the reader ever looked at the plain white building, with successive rows of little windows, which so often spans the breadth of our smaller streams?  If he has, the thought has at once arisen that within those walls huge wheels and heavy-revolving stones remorselessly tear and crush to powder heaps upon heaps of yellow grain, with a power that is equal to the combined effort of a whole troop of horses concentred in the task.  But we question very much whether