This composer had second 
This composer had second violins play the title Ostinato throughout a suite for strings that oscillates between 6/8 time and 9/8 time in its opening Jig. That piece borrows its finale from the "Fantasia on the Dargason" movement of this composer's Second Suite in F for Military Band. Strings use the wooden part of their bows to play a march in 5/4 time at the start of a piece by this composer whose central movement provides the melody for the hymn "I Vow to Thee, My Country." That "Bringer of Jollity" movement is flanked by depictions of Mercury and Saturn. For 10 points, name this composer of The Planets.