Conscription of the Senators and the Name 'Conscript Fathers'
Tarquin the Proud had ordered senators assassinated. Upon ousting the king, Brutus replaced the number of senators, bringing it "back" up to 300. Not patricians, but equestrian noblemen filled the ranks. These equestrians were "called up" or "conscripted", for which reason the senators (both those called up and the others) were called conscripti:7. Brutus, with the consent of his colleague, was first attended by the fasces, he who proved himself afterward as keen in protecting liberty as he had previously shown himself in asserting it. First of all he bound over the people, jealous of their newly-acquired liberty, by an oath that they would suffer no one to be king in Rome, for fear that later they might be influenced by the importunities or bribes of the royal house. Next, that a full house might give additional strength to the senate, he filled up the number of senators, which had been diminished by the assassinations of Tarquinius, to the full number of three hundred, by electing the principal men of equestrian rank to fill their places: from this is said to have been derived the custom of summoning into the senate both the patres and those who were conscripti. They called those who were elected, conscripti, enrolled, that is, as a new senate. It is surprising how much that contributed to the harmony of the state, and toward uniting the patricians and commons in friendship.
The Senators Work for the Roman People
Preventing the Roman People from longing for the days of kings (remember, when there was the period of interregnum, the people had felt as though they had many masters instead of the preferred, single monarch) the Senate granted them many financial concessions:8. Many concessions were therefore granted to the people by the senate during that period by way of conciliating them. Their attention, in the first place, was directed to the markets, and persons were sent, some to the country of the Volscians, others to Cumae, to buy up corn. The privilege of selling salt also was withdrawn from private individuals because it was sold at an exorbitant price, while all the expense fell upon the state: and the people were freed from duties and taxes, inasmuch as the rich, since they were in a position to bear the burden, should contribute them; the poor, they said, paid taxes enough if they brought up their children. This indulgence on the part of the fathers accordingly kept the state so united during their subsequent adversity in time of siege and famine, that the lowest as much as the highest abhorred the name of king; nor did any single individual afterward gain such popularity by intriguing practices, as the whole body of the senate at that time by their excellent government.
Decuries and Interregnum
The 100 senators were divided into ten decuries. Each decury had a leader. Each leader was given the accoutrements of the king, lictors and insignia, for five days, and then the rule was passed on to the next decury's leader. The interregnum was the period between kings. The ruling senator was an interrex. Later, the interregnum was used for the period between consuls, and even later, between popes.
Summoning of the Senate
The Senate was first assembled by the kings, but after the kings were expelled, the consuls had the Senate meet. Alternatively, praetors, dictators, masters of horse, decemviri, tribunes, interreges, and prefects might assemble the Senate. There might be an edict summoning the senators or a public crier. They had to assemble in an area sanctified by the augurs.

