concerning their limbs and the suspensions belonging to the single timbers at intervals on both ram-bearing tortoises and towers and double ladders, and furthermore the useful gangways made by means of them to the wall, having clarified in detail for the appropriate successive work for each in the present treatise, we have set it forth. If we wish to break through and tear apart walls or gates more quickly with rams, we shall make tall, four-wheeled, ram-bearing tortoises, having from above chains or strong ropes of great thickness that carry and hold up the ram; for being carried from a high point, the ram takes a greater distance behind for its movement, and being brought forward from afar and swung, it is more empowered and, striking the wall, delivers a violent and powerful blow. Let the tortoise be tall in appearance and not so large, so that it may be easily moved for its motion, having a height double its width, and a length equal to or a little less than its height, so that it may be sharp-roofed and elongated, so that the weights falling upon it, being cast sideways, may slide off below. And it is constructed as follows. Two and two beams are placed, being 24 feet each in length, standing apart from each other 226 not less than 12 feet; and to them are fitted timbers 12 digits in thickness, not less than a foot in width, 24 feet in height, being eight in number, four and four standing up from each of the side parts; and converging from above at the peak they meet each other, enclosing a timber, which is the ridge of the tortoise, longer than the length of the beams, and projecting in front for reasons we shall state as we proceed. And on whichever part we want the tortoise to incline, let other beams be nailed to these at the middle of the uprights, and from the inner part let props be placed underneath, supporting and strengthening the middle beams and the ridge; and on the outer surface let the uprights be covered with planks four digits in thickness. And thus the structure is completed. And from the base of the inner beams, let the outer ones be propped up with upright timbers, being uninclined and perpendicular; and let the space between around the lower beams, that is, the interval, have four wheels that hold up and carry the whole framework of the tortoise. And so that the lower beams may not open up, it should have collars, not made with an external cut 227, but holding firm by the nailing on of plates, as if of certain cut-off fist-like shapes, and carved hemispheres similar to those placed on the pivots of doors, which will be the bases of the sharp-roofed tortoise. And sometimes the roof of the tortoise is made more obtuse and lower, when on the middle posts standing upright on the beams there are added from above the so-called "synkyptai" and they enclose the highest ridge of the gable, when the ram is evidently very long and the tortoise is standing far from the wall. For if the ram should happen to be shorter in length and the tortoise be nearer the wall, it will not be able to withstand the weights being hurled down and falling upon it because of the lowness of its roof, but suffering a breach or a fracture at the meeting-points of its joints, it will become dangerous to itself and to the ram-fighters. And the ridge, which is held from above by the aforesaid adjacent upright single timbers, must project in front towards the face of the wall, so that on it there may be a protective covering and it may receive the things sent against the ram; for if the very large stones carried down from the wall and the transverse timbers coming down equally, with equal weight and equal balance, should strike the uncovered ram as it is being brought against the wall, either the ram itself, having been turned aside, will be torn apart, or it will throw off and kill those moving it. Such then is the front tortoise 228 which also has the supports of the ram at an interval. And the second is lower in height and smaller; and two others behind are still smaller; for they happen to be necessary for the safety of the passage. But it is necessary for them to be more numerous and small, as we have said before, because of
περὶ κῶλα αὐτῶν καὶ τὰς ἐπὶ τῶν μονοξύλων κατὰ διάστασιν ἀνηκούσας ἀρτήσεις ἐπί τε κριοφόρων χελωνῶν πύργων τε καὶ τῶν διπλῶν κλιμάκων καὶ ἔτι τὰς δι' αὐτῶν πρὸς τὸ τεῖχος γινομένας εὐεργεῖς διαβάθρας, πρὸς τὴν ἁρμόζουσαν ἐφεξῆς ἑκάστῳ ἐργασίαν ἐπὶ τῆς προκειμένης πραγματείας λεπτομερῶς διασαφήσαντες ἐξεθέμεθα. Ἐὰν τάχιον μετὰ κριῶν θελήσωμεν τείχη ἢ πόρτας ῥηγνύειν καὶ διασπᾶν, κριοφόρους ποιήσομεν χελώνας τετρατρόχους ὑψηλάς, ἄνωθεν ἁλύσεις ἢ σχοινία εὔτονα κατὰ πάχος ἐχούσας τὰ τὸν κριὸν βαστάζοντα καὶ ἀνέχοντα· ἀφ' ὑφηλοῦ γὰρ βασταζόμενος ὁ κριὸς πλέον ὄπισθεν διάστημα πρὸς τὴν κίνησιν λαμβάνει, καὶ ἐκ μακροῦ ἐπιφερόμενος καὶ ἐνσειόμενος πλέον ἐνδυναμοῦται καὶ προσκρούων τῷ τείχει βιαίαν καὶ ἰσχυρὰν ἀποτελεῖ τὴν πληγήν. Ἔστω δὲ τῷ εἴδει ὑψηλὴ ἡ χελώνη καὶ μὴ τοσοῦτον μεγάλη, ἵνα πρὸς τὴν κίνησιν εὐπαράγωγος ᾗ, διπλάσιον τὸ ὕψος τοῦ πλάτους ἔχουσα, τὸ δὲ μῆκος τοῦ ὕψους ἴσον ἢ μικρῷ ἔλασσον, ἵνα ὀξύρρυτος καὶ ἐπιμήκης εἴη, ὡς ἂν τὰ ἐν αὐτῇ ἐπιπίπτοντα βάρη πλαγιαζόμενα παρεκτρέχῃ κάτωθεν. Κατασκευάζεται δὲ οὕτως. Ζυγὰ δύο καὶ δύο τίθενται μήκους ὄντα ἀνὰ ποδῶν ˉκˉδ, διεστῶτα ἀπ' ἀλλήλων 226 ποδῶν οὐκ ἔλασσον ˉιˉβ· καὶ πρὸς αὐτὰ ἐμβάλλονται ξύλα δακτύλων κατὰ πάχος ˉιˉβ, πλάτους ποδὸς οὐκ ἔλαττον, ˉκˉδ ποδῶν πρὸς ὕψος, ἀριθμῷ ὄντα ὀκτώ, τέσσαρα καὶ τέσσαρα ἀφ' ἑκατέρων τῶν πλαγίων μερῶν ἐφιστάμενα· συννευόντα δὲ ἄνωθεν κατὰ κορυφὴν συμβάλλει ἀλλήλοις, περιλαμβάνοντα ξύλον, ὅ ἐστι ῥάχις τῆς χελώνης μακρότερον τοῦ περὶ τὰ ζυγὰ μήκους, καὶ παρεξέχον ἔμπροσθεν δι' ἃς προϊόντες λέξομεν αἰτίας. Καθ' ὃ δὲ μέρος τὴν χελώνην προσνεύειν βουλόμεθα, κατὰ μέσους τοὺς ὀρθοστάτας τούτοις ἄλλα ζυγὰ προσηλούσθω, καὶ ἐκ τοῦ ἔσωθεν μέρους ὑποβεβλήσθωσαν παραστάται ἀντέχοντες καὶ στηρίζοντες τὰ μέσα ζυγὰ καὶ τὴν ῥάχιν· τῇ δ' ἔξωθεν ἐπιφανείᾳ σανίσι κατὰ πάχος τετραδακτύλοις οἱ ὀρθοστάται σκεπέσθωσαν. Καὶ οὕτως συντελεῖται τὸ σχῆμα. Ἀπὸ δὲ τοῦ ἐδάφους τῶν ἔσω ζυγῶν ὑποστυλούσθω τὰ ἔξω ξύλοις ὀρθοῖς, ἀκλινέσι κατὰ κάθετον οὖσι· τὸ δὲ μεταξὺ κένωμα τὸ περὶ τὰ κάτω ζυγά, τουτέστι τὸ διάστημα, τροχοὺς τέσσαρας ἐχέτω τοὺς ἀνέχοντας καὶ βαστάζοντας τὸ ὅλον περὶ τὴν χελώνην σύμπηγμα. Ἵνα δὲ μὴ ἀνοίγηται τὰ κάτω ζυγά, περιστομίδας προσλάβοι οὐκ ἔξω τομῆς 227 γινομένης, ἀλλὰ χελωνίων προσηλώσει κρατούσας, ὡσανεὶ γρονθαρίων τινῶν περικεκομμένων, καὶ ἡμισφαιρίων ἐγγεγλυμμένων παρομοίων τοῖς ἐπὶ τῶν στροφίγγων τῶν θυρῶν τιθεμένοις, αἳ βάσεις ἔσονται τῆς ὀξυρρύτου χελώνης. Γίνεται δὲ ὁτὲ ἀμβλυτέρα καὶ ταπεινοτέρα ἡ τῆς χελώνης στέγη, ὅταν ἐπὶ τῶν μεσοστατῶν τῶν ἐπὶ τὰ ζυγὰ ὀρθίων ἑστώτων ἄνωθεν προστεθῶσιν οἱ λεγόμενοι συγκύπται καὶ τὴν ἀνωτάτην τοῦ ἀετώματος περιλάβωσι ῥάχιν, μακροτάτου δηλονότι τοῦ κριοῦ ὄντος καὶ τῆς χελώνης πόρρω τοῦ τείχους ἀφεστώσης. Εἰ γὰρ ἐλάσσων ὁ κριὸς κατὰ μῆκος τύχῃ καὶ ἡ χελώνη τοῦ τείχους ἔγγιον εἴη, οὐ δυνήσεται ἀντέχειν πρὸς τὰ ἐπικρημνιζόμενα καὶ πρὸς αὐτὴν ἐπιπίπτοντα βάρη διὰ τὸ τῆς στέγης ταπείνωμα, ἀλλὰ ῥῆξιν ἢ θραῦσιν ἐπὶ ταῖς ἁρμονιῶν λαβοῦσα συμβολαῖς ἐπισφαλὴς ἑαυτῇ τε καὶ τοῖς κριομαχοῦσι γενήσεται. Τὴν δὲ ὑπὸ τῶν προειρημένων παρορθίων μονοξύλων ἐπιλαμβανομένην ἄνωθεν ῥάχιν χρὴ παρεξέχειν ἔμπροσθεν κατὰ πρόσωπον τοῦ τείχους, ἵνα ἐπ' αὐτὴν προστέγασμα ᾗ καὶ τὰ ἐπὶ τῷ κριῷ πεμπόμενα προσδέχηται· εἰ γὰρ οἱ ἀπὸ τοῦ τείχους καταφερόμενοι μέγιστοι λίθοι καὶ τὰ πλάγια ξύλα τὰ ἐξ ἴσου ἰσοβαρῶς καὶ ἰσοζύγως κατερχόμενα ἀστέγαστον τύπτωσι τὸν κριὸν τῷ τείχει ἐπιφερόμενον, εἴτ' αὐτὸς ὁ κριὸς περινεύσας διασπασθήσεται, ἢ τοὺς κινοῦντας ἀπορρίψει καὶ διαφθερεῖ. Τοιαύτη μέν ἐστιν ἡ ἔμπροσθεν χελώνη 228 ἡ καὶ τὰς βασταγὰς τοῦ κριοῦ κατὰ διάστασιν ἔχουσα. Ἡ δὲ δευτέρα ταπεινοτέρα πρὸς ὕψος καὶ ἐλάσσων· καὶ ἄλλαι δύο κατόπισθεν ἔτι ἐλάσσονες· πρὸς ἀσφάλειαν γὰρ παρόδου ἀναγκαῖαι τυγχάνουσι. Πλείονας δὲ δεῖ αὐτὰς εἶναι καὶ μικράς, ὡς προείπομεν, διὰ