In hailstone the first element may be Mid.
"The Romance of Names"
Ernest Weekley
He was standing in the middle of the room, gazing out at the falling hail, when a hailstone, cutting through the thatched roof, struck him on the head and killed him instantly.
"Far Away and Long Ago"
W. H. Hudson
The famous collection of the late Mrs. hailstone was sold in 1909. This lady had for many years been known as a lace collector, and the sale of her effects was eagerly anticipated.
"Chats on Old Lace and Needlework"
Emily Leigh Lowes