[III.9] This is mainly Steevens's (1773) stage direction. Capell's (1768) is interesting: "Artemidorus is push'd back. Cæsar, and the rest, enter the Senate: The Senate rises. Popilius presses forward to speak to Cæsar; and passing Cassius, says,..."
[III.10] makes to: advances to, presses towards.
[III.11] mark. No necessity to pronounce this as dissyllabic. The pause has the effect of a syllable.
[III.12] constant: firm. So in [ll. 60], 72, 73. Cf. [II, i, 227], [299]; [iv, 6].
[III.13] So in Plutarch, Marcus Brutus: "Another senator called Popilius Læna after he had saluted Brutus and Cassius more friendly than he was wont to do, he rounded[1] softly in their ears, and told them, 'I pray the gods you may go through with that you have taken in hand; but, withal, dispatch, I read[2] you, for your enterprise is bewrayed.' When he had said, he presently departed from them, and left them both afraid that their conspiracy would out.... When Cæsar came out of his litter, Popilius Læna went ... and kept him a long time with a talk. Cæsar gave good ear unto him; wherefore the conspirators ... conjecturing ... that his talk was none other but the very discovery of their conspiracy, they were afraid every man of them; and one looking in another's face, it was easy to see that they all were of a mind, that it was no tarrying for them till they were apprehended, but rather that they should kill themselves with their own hands. And when Cassius and certain other clapped their hands on their swords under their gowns, to draw them, Brutus marking the countenance and gesture of Læna, and considering that he did use himself rather like an humble and earnest suitor than like an accuser, he said nothing to his companion (because there were many amongst them that were not of the conspiracy), but with a pleasant countenance encouraged Cassius; and immediately after, Læna went from Cæsar, and kissed his hand.... Trebonius on the other side drew Antonius aside, as he came into the house where the Senate sat, and held him with a long talk without." In the Julius Cæsar Plutarch makes Decius detain Antony in talk.
[III.13[1] i.e. whispered.
[III.13[2] i.e. advise.
[III.14] [Exeunt Antony ...] Ff omit.
[III.15] presently: immediately, at once. So Shakespeare and other Elizabethan writers always use the word. See [l. 143]; [IV, i, 45].
[III.16] address'd: prepared. Often so in sixteenth century literature. Cf. As You Like It, V, iv, 162; Henry V, III, iii, 58; 2 Henry IV, IV, iv, 5. This old meaning survives in a well-known golf term.