The fiery orbs above and the twinn'd stones
Upon the number'd beach."
Theobald, I think, was right in reading 'unnumber'd.'
"The murmuring surge
That on the unnumbered idle pebbles chafes."
Lear, iv. 6.
The joining it with 'beach' seems an instance of the figure called Hypallage. The stones are called 'twinn'd' from their resemblance to each other.
"Beseech you, sir, desire my man's abode