sandpipes

Noun

sandpipe (plural sandpipes)

1. A pipe conveying sand, as in a steam locomotive, where it deposits sand directly in front of the driving wheels to aid traction.
   • In the modified locomotive, the leading sanding gear is restored and the sandpipes which formerly led to the trailing coupled wheels are reversed to provide sanding behind the driving wheels for rearward running.1956 April, “"Merchant Navy" Class Pacific Modified”, in Railway Magazine, page 212
2. A perpendicular cylindrical hollow, tapering to a point, occurring in chalk deposits, and usually filled with sand, gravel, or clay.
   • Some of the enormous fragments of chalk which are interstratified with drift have not only layers of undisturbed flints, but also sandpipes in the middle of them, or cylindrical cavities filled with sand and gravel […]1840, Philosophical Magazine, page 365