1 Tho up they began their merry pipes to truss,
Tho > Then truss > pack
2 And all their goodly herds did gather round, 3 But every satyr first did give a buss
buss > kiss (OED cites Robert Herrick (1591-1674): "We busse our Wantons, but our Wives we kisse")
4 To Hellenore: so busses did abound. 5 Now gan the humid vapour shed the ground
gan > did shed > sprinkle
6 With pearly dew, and the earth's gloomy shade 7 Did dim the brightness of the welkin round:
welkin > {The apparent arch or vault of heaven overhead}
8 That every bird and beast awarned made,
every > [all severally: all the birds and beasts] awarned > warned (WU)