He's rocking the canister to keep the sand flowing smoothly.
While the outside guy is refilling the canister, I shoot a photo through the smokebox tubesheet, lens through one hole and flash through the (sort of) above hole. The shadow is caused by not getting the flash close enough to the tubesheet. The inside guy is using this break in the action to make an inspection.
At another break in the action, they bring Walt Eisenman, our Chief Mechanical Officer in for a look-see.
Preparing to go in the smokebox and do the outside of the tubesheet.
At work around the tubesheet.