I am a man of forty pounds of steam, up to 100 pounds of pressure, and of 150 pounds

I am a man of forty pounds of steam, up to 100 pounds of pressure, and of 150 pounds of working power. I am easily worked up to 100 pounds of steam, but easily worked down to forty. I can work up to 100 pounds of power, but cannot work below forty. I can be worked up to 100 pounds of working power in an hour, but must be worked down to forty in the same time. I can be worked up to 100 pounds of working power in ten hours, but must be worked down to forty in the same time. I have 100 pounds of working power, but only forty of actual working pressure. I am easily raised to 100 pounds of working pressure, but cannot be raised above that. I am easily lowered to