sounde ye day of ye Lorde

Presumably out loud, in the adrenalin of having reached the summit and the lightheadedness of semi-starvation. William Penn says ‘Upon this Mountain he was moved of the Lord, to sound out his Great and notable Day, as if he had been in a great Auditory’.

Probably from Joel 2:

1.       Blow ye the trumpet in Zion, and sound an alarm in my holy mountain: let all the inhabitants of the land tremble: for the day of the Lord cometh, for it is nigh at hand;
2.       A day of darkness and of gloominess, a day of clouds and of thick darkness, as the morning spread upon the mountains: a great people and a strong; there hath not been ever the like, neither shall be any more after it, even to the years of many generations ...

The ‘great people’ are ‘the northern army’ which biblical comentators have identified either with the invading Assyrians/Chaldeans or metaphorically with an army of locusts. They are to panic Israel into repentance and a return to the ways of the Lord. Joel goes on to say that they will be driven back into the north: but narrative consistency is not to the fore in the interpretation of the Scriptures at this time.

Israel's repentance will lead to the millennial promise at the end of the chapter:

28.       And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions:
29.       And also upon the servants and upon the handmaids in those days will I pour out my spirit.

Fox used this passage to justify women's prophesying, especially in The Woman Learning in Silence (London: Thomas Simonds, 1656).