Interesting quotes on the cross: article from on cruxifiction:
"During this early period, a wooden beam, known as a furca or patibulum was placed on the slave's neck and bound to his arms. The slave was then required to march through the neighborhood proclaiming his offense. This march was intended as an expiation and humiliation. Later, the slave was also stripped and scourged, increasing both the punishment and the humiliation. Still later, instead of walking with his arms tied to the wooden beam, the slave was tied to a vertical stake................A soldier at the head of the procession carried the titulus, an inscription written on wood, which stated the defendant's name and the crime for which he had been condemned. Later, this titulus was fastened to the victim's cross. When the procession arrived at the execution site, a vertical stake was fixed into the ground. Sometimes the victim was attached to the cross only with ropes. In such a case, the patibulum or crossbeam, to which the victim's arms were already bound, was simply affixed to the vertical beam; the victim's feet were then bound to the stake with a few turns of the rope.......If the victim was attached by nails, he was laid on the ground, with his shoulders on the crossbeam. His arms were held out and nailed to the two ends of the crossbeam, which was then raised and fixed on top of the vertical beam." Biblical Archaeology Review, January-February 1985
"The very form of the cross, too, has five extremities, two in length, two in breadth, and one in the middle, on which [last] the person rests who is fixed by the nails" (Irenaeus c. 130-202), Adversus Haereses II, xxiv, 4
Seneca the Younger (c. 3 BC - 65 AD) was a Ancient Rome Stoicism philosopher statesman; he was tutor and advisor to Nero and lived at the same time as Jesus. In describing this form of torture, he said: "I see crosses there, not just of one kind but made in many different ways: some have their victims with head down to the ground; some Impalement their private parts; others stretch out their arms on the gibbet."