O days and hours, your work is this To hold me from my proper place, A little while from his embrace, For fuller gain of after bliss:
That out of distance might ensue Desire of nearness doubly sweet; And unto meeting when we meet, Delight a hundredfold accrue,
For every grain of sand that runs, And every span of shade that steals, And every kiss of toothed wheels, And all the courses of the suns.
This new friendship will make Tennyson's time on earth a bit happier, so he can experience the "fuller gain" of happiness in Arthur's company when they reunite in the afterlife.
You've heard that old saying, "Distance makes the heart grow fonder"? That's exactly what Tennyson is saying in the second stanza. He's hoping that once he and Arthur meet in Heaven, their happiness will be as great as every grain of sand, every patch of shade, every gear that locks into every other gear, and all the distance that the sun travels.