The Merseburg wheel had an axle of just under six inches (5.6inches) and it turned at around 40 rpm although some reports indicated a speed of 50 rpm, perhaps when unloaded. A 5.6 inch axle has a circumference of 17.58 inches, so for a rope wrapped around the wheel it would travel 17.58 inches for each turn of the wheel. 40 turns would lift a weight more than 58 feet in one minute, to the top of the Schloss Merseburg.
When Wolff visited Merseburg he commented on the pulley system and included it in his report, suggesting that this might indicate that the wheel was not very powerful. But there are a couple of things to bear in mind about this report.
Firstly Wolff was on the brink of accepting an offer of a very senior position with the Czar of Russia, Peter the Great, and we know that the Czar was planning to buy Bessler’s wheel, and Wolff stated that he could improve the performance of the wheel if he were allowed to have access to it in his new position. So take his apparent dismissal of the wheel's power with a large pinch of salt.
Secondly, Bessler was the consummate showman and having noted Wolff’s comments about the pulleys he designed a wheel which moved more slowly but with the same amount of power. I think Bessler added the pulleys at Merseburg, to slow down the lift because a one minute lift created its own problems.
For a start Bessler needed his brother down in the castle yard to load the chest of bricks to the rope and shout when he was ready. Someone had to tell Bessler when to stop the wheel when the box reached the pulley, outside the window. Then he needed to reverse the lift back down to his brother and stop the wheel before it completely unravelled from the axle. A second demonstration immediately could be arranged and repeated as often as wished, but how much better if he slowed the lift down fourfold. More time for each lift, more time for the witnesses to study the wheel in action, and fewer demonstrations necessary to show its lifting power without any loss in performance.
Also with all the witnesses crowded into the machine room, watching Bessler, and peering out the windows to see the load going up and down, it must have been difficult to satisfy everyone present. No wonder he decided to make the wheel at Kassel turn more slowly. He did state that he could make wheels with different speeds and lifting capabilities and of various sizes.
One more thing; we note that the chest held about 70 lbs of stones. Have you ever lifted 70lbs? The average hold luggage on an aircraft is about 50lbs, so 70lbs is probably more than sufficient to make the point.