Casgliadau Arlein

"Sinker". Symbol HD4. The Holman HD4 is a hand hammer drill for sinking purposes, using larger steel than HD3 and has proved a very successful drill. The recent records in South Africa is substantial evidence of its general usefulness and conclusively proves its efficiency. It may be interesting to note that the total cost of machine spares for sinking 780 feet in this shaft was £156 11s 0d. Average 4.01 shillings per foot of sinking.