What is this tank next to our hot water heater?

It is very loud, is it safe to put a towel over it to reduce the rattling noise?

What is this horizontal piston-like thing connecting the body of two passenger train carriages with each other / with the bogey?

Weird black and white sand substance around our furnace in our basement

4 inch metal bolt with a spinning wheel around the head. "TG" is written on the top.

Wooden handle metal loop, plugs into wall, stamped with “pioneer electric 500watt 120volt model 622”

What is this marble marker in the sidewalk in Burlington, Vermont?

I found two of these markers in the sidewalk along South Willard Street and then one in the second block of Howard Street? Are these historic property markers or do they have some other significance?

What is this thing? The inside opens up to empty space, it’s disconnected from the desk below

What is this tiny tool? Looks like a large cribbage peg but comes apart and a small crooked pin pulls out of the base. Bought in set of two at a thrift store. About 2 inches long.

What is this round metal thing on the side of a restaurant?

Found on a WW1 battlefield (Somme, France). Does anyone recognize what this can be.

Black plastic restrictor thing in the vent pipe dedicated for a kitchen hood