How did the introduction of the double-acting engine alter power production compared to single-acting designs?

Steam was admitted alternately to both sides, producing power on both the upstroke and the downstroke

Early steam engines, including Newcomen's and Watt's initial designs, were single-acting, meaning steam pressure only drove the piston in one direction (downward), with the return stroke relying on external forces like the weight of the machinery or the pump structure itself. Watt introduced the double-acting engine where steam was admitted sequentially to both sides of the piston. When steam pushed the piston down on one side, steam was simultaneously being prepared or admitted to the opposite side for the return stroke. This meant the engine delivered a continuous impulse, generating power during both the upward and downward movements, leading to much smoother operation and significantly greater, more consistent power output from the same physical apparatus.