Moreover, at the level of the first story three openings were made, which in time of war were furnished with screens, and which afforded front and side views. Munitions of war were hoisted to the higher stories by means of pulleys suspended in the round-arched openings, K (_vide_ plan of the first story). The other gates were constructed on the same model, the outworks alone being different, according to the disposition of the ground. [Illustration: FIG. 19] Fig. 20 gives a general view of the great _tête de pont_ on the south, the _place d'armes_ and the battlemented wall ascending to the square tower on the south angle of the cité, and the _castellum_. The square towers were not covered by roofs but by platforms, so as to allow catapults or _onagri_ to be placed upon them.[8] [Illustration: FIG. 20.] With this design quadrangular towers of the kind described were raised at the salient angles of the defences, which were weak points, but which, on the other hand, facilitated the discharge of missiles over a more extensive field. In case a front was attacked, propulsive machines were set up behind the curtains on earthworks or wooden platforms. The city thus strongly fortified was in a position to resist and defy the attacks of the barbarians, who, at that period of their history, were unable to undertake the siege of a stronghold well planned and defended. FOOTNOTES: [Footnote 4: A pace was equivalent to three feet.] [Footnote 5: The Gallic foot was the _pied du roi_ (thirteen inches).] [Footnote 6: The dark line indicates the habitations preserved, the red line the tenements rebuilt on the sites left unoccupied after the clearing necessary for the fortifications and their approaches.] [Footnote 7: These new roads are indicated by red lines.] [Footnote 8: The catapults could discharge bolts six feet long and very heavy. The _onagri_ hurled stones of sixty pounds weight to a maximum distance of two hundred and fifty paces.] CHAPTER VIII. _THIRD SIEGE._