Hello Chuck Lee- Boilers were fed by reciprocating pumps, one also might refer to them as plunger pumps. These were pistons.
The forced air induction boiler was common during the Civil War period. For specific mention of this system and complaints about shortcomings of the early armored Federal vessels I've found the joint report of Monitor type commanders useful. It is in the Official Records, South Atlantic Blockading Squadron and is dated May 25, 1863. The document written and sent to the Department from the meeting of commanders aboard the U.S.S. Passaic while anchored in North Edisto. Specific mention of induction drive belts (leather) slipping when wet. Regards.