This was a Friday, day 9 in Dublin, of 23. Mahmud's entry is in error; what he describes too place on Sunday.
Rob Stockman's assessment is that Mahmud kept his notes on little scraps of paper and sometimes got them jumbled. In this case, it's particularly frustrating because Agnes only says, "Before the talk began, I told the people that Abdu'l-Baha would speak every afternoon at 1/4 to 6."
That is ALL! So we are left to wonder, who came to hear Him? What occurred on that day? Will any whispering breeze from the past inform us?