Steam pressure gauge made by David Auld & Sons Ltd. Needle works with compressed air up to 25 psi. Housing is in brass. Width is 4 inches across face and 5 inches across rear mounting plate. Depth is 1 3/4 inch.
Broken down. Not working. Could bake a working engine from the 2. Found in grandfathers / uncles garage along with large amount of other de Dion parts..