The neglect of the hours and minutes in their calculation of the length of the year became with them, as with the Egyptians, a source of serious embarrassment, and we are still ignorant as to the means employed to meet the difficulty.  The months had relations to the signs of the zodiac, and the days composing them were made up of twelve double hours each.  The Chaldaens had invented two instruments, both of them of a simple character, to measure time—­the clepsydra and the solar clock, the latter of which in later times became the source of the Greek “polos.”  The sun-dial served to determine a number of simple facts which were indispensable in astronomical calculations, such as the four cardinal points, the meridian of the place, the solstitial and equinoctial epochs, and the elevation of the pole at the position of observation.  The construction of the sundial and clepsydra, if not of the polos also, is doubtless to be referred back to a very ancient date, but none of the texts already brought to light makes mention of the employment of these instruments.*

* Herodotus (ii. 109) formally attributes the invention of the sun-dial and polos to the Babylonians.  The “polos” was a solar clock.  It consisted of a concave hemisphere with a style rising from its centre:  the shadow of the style described every day an arc of a circle parallel to the equator, and the daily parallels were divided into twelve or twenty-four equal parts.  Smith discovered, in the palace of Sennacherib at Koyunjik, a portion of an astrolabe, which is now in the British Museum.

All these discoveries, which constitute in our eyes the scientific patrimony of the Chaldaeans, were regarded by themselves as the least important results of their investigations.  Did they not know, thanks to these investigations, that the stars shone for other purposes than to lighten up the nights—­to rule, in fact, the destinies of men and kings, and, in ruling that of kings, to determine the fortune of empires?  Their earliest astronomers, by their assiduous contemplation of the nightly heavens, had come to the conclusion that the vicissitudes of the heavenly bodies were in fixed relations with mundane phenomena and events.  If Mercury, for instance, displayed an unusual brilliancy at his rising, and his disk appeared as a two-edged sword, riches and abundance, due to the position of the luminous halo which surrounded him, would be scattered over Chaldaea, while discords would cease therein, and justice would triumph over iniquity.  The first observer who was struck by this coincidence noted it down; his successors confirmed his observations, and at length deduced, in the process of the years, from their accumulated knowledge, a general law.  Henceforward, each time that Mercury assumed the same aspect it was of favourable