of the laws of motion to the design of machines." The other mathematical marvel that is noted in Leonardo's designs of the crossbows is the proportional techniques that he utilized in every aspect of the designs. Mechanically, the Rapid Fire Crossbow's tiller was split into two stacked wooden pieces held together at the front by a hinge and held in place at the back by a spring-loaded latch. Sandwiched inside the tiller, a pair of interconnected folding levers attach the lower half of the tiller to a sliding plank sitting on the top half of the tiller between the two metal prods, similar in mechanical concept to the Gastraphetes, that contained the rolling nut and spring-loaded sear at the back of the plank. Meanwhile, the bottom half of the tiller contained the trigger. Upon pressing a switch on the side of the tiller to release the latch, the user can then fold the bottom half of the tiller down. At the same time, the interconnected levers then push the sliding plank forward until the drawstring is caught by the rolling nut, which is held secure by the sear's spring tension. Upon pushing the bottom half of the tiller back into place, the latch locks the upper and lower halves of the tiller back together. After a bolt is loaded on the crossbow and aimed, the trigger is then pulled to compress the sear's spring and enable the rolling nut to release the drawstring to propel the bolt. Such a design removed the need for external spanning tools that an arbalist had to carry and simplified the arming process of the crossbow. With regards to the Giant Crossbow, the original idea of Leonardo, as described in the drawings of the Codex Atlanticus (1488–1489), was to build a large crossbow in order to increase the range and power of its ammunition. The Giant Crossbow was used to fire rocks and bombs; it was mostly intended to be an intimidation-based weapon for deterring foes from attacking. The Giant Crossbow was made up of thin wood, on 6 wheels, 27 yards across, and made up of 39 separate parts. While some believe that Leonardo designed the Giant Crossbow for his own amusement, the context around this design suggests the Giant Crossbow truly was intended to be a dangerous weapon that would greatly appeal to his employer, Ludovico Sforza. Inspiration for such a weapon most