Final answer:
A special engineer's license would allow you to operate high and low-pressure boilers and their appurtenances of not more than 50 horsepower.
Step-by-step explanation:
A special engineer's license would allow you to operate high and low-pressure boilers and their appurtenances of not more than 50 horsepower. This means that you would have the authority to work with boilers that have a maximum power output of 50 horsepower, whether they are low-pressure or high-pressure boilers.