This Bourdon pressure gauge was found in 1983 at the West Wiley Mine site (PA841), which was active from 1905 until 1926 for coal mining, on land administered by the Wyoming Bureau of Land Management.
It is a medium-sized 5" pressure gauge made by J.E. Lonergan. On the bottom of the gauge face is the trademark Lonergan logo with the manufacturing location, "Phila.", below it. The horse-shoe display shows a scale of 0-300 psi, which is marked at intervals of 25. At the top of the gauge are what appear to be the letters "BO_CK". Like so many gauges contemporaneous to this one, this is presumably the name of the company for which the gauge was manufactured.