The History of Rome (1.18.5-1.18.9)

When Numa's name was mentioned, though the Roman senators saw that the balance of power would be on the side of the Sabines if the king were chosen from amongst them, still no one ventured to propose a partisan of his own, or any senator, or citizen in preference to him. Accordingly they all to a man decreed that the crown should be offered to Numa Pompilius.

He was invited to Rome, and following the precedent set by Romulus, when he obtained his crown through the augury which sanctioned the founding of the City, Numa ordered that in his case also the gods should be consulted. He was solemnly conducted by an augur, who was afterwards honoured by being made a State functionary for life, to the Citadel, and took his seat on a stone facing south.

The augur seated himself on his left hand, with his head covered, and holding in his right hand a curved staff without any knots, which they called a “ lituus.” After surveying the prospect over the City and surrounding country, he offered prayers and marked out the heavenly regions by an imaginary line from east to west; the southern he defined as “the right hand,” the northern as “the left hand.”

He then fixed upon an object, as far as he could see, as a corresponding mark, and then transferring the lituus to his left hand, he laid his right upon Numa's head and offered this prayer:

“Father Jupiter, if it be heaven's will that this Numa Pompilius, whose head I hold, should be king of Rome, do thou signify it to us by sure signs within those boundaries which I have traced.”