Working in the cab of a steam engine in the summer is just plain a "hot" job!...In my experience, I got to fire the Durango-Farmington branch a number of times...going down in the morning, you were on the left side of the cab..in the hot sun early in the day. Coming back in the afternoon, you were still in the hot sun on the left side late in the day....We all carried canvas water bags that held a gallon or so of water, and we drank 'em dry and refilled at every water stop (if the water was any good...some places it wasn't). You didn't want to get too dehydrated, else you'd get sicker than hell.
At the end of the day, your overalls would stand up by themselves from the salt accumulation in dried sweat.