The elder Sellers was convinced the machine was a hoax. To validate his suspicions, he hired local engineer Isaiah Lukens to build a similar machine, using a hidden clockwork motor as a power source. They then arranged a demonstration of the machine to Redheffer, who was immediately convinced and offered to buy it. Meanwhile, Redheffer's machine appeared in the "Philadelphia Gazette". Civil engineer Charles Gobort offered to bet sums of money ranging from $6,000 to $10,000 that the machine was genuine, and that Redheffer had discovered perpetual motion.