on removing them — this was the problem that 

 Lukens undertook to, and did solve, in so ingenious 

 a way that the deception was perfect, and to my 

 knowledge never discovered, though repeatedly ex- 

 amined by the most thorough and ingenious men 

 of that period. 



The beautiful machine he made for the Philadelphia 

 Museum was mostly of mahogany; it had a massive 

 rectangular base, within which the clock spring and 

 gearing was concealed; at each corner of the base 

 rose a mahogany column, each column above its 

 entablature finished by a mahogany ball; from one 

 of these balls a steel rod passed down through the 

 center of the column to the gearing in the base, 

 making it by the ball a "stem winder." Diagonally 

 from the column were the beams to carry the glass 

 box for the upper journal of the main upright shaft, 

 which was of wood, octagonal, in imitation of 

 Redheffer's, with wing gudgeons for both lower step 

 and upper journal. The lower step journal was of 

 much greater diameter than the upper, in model, as 

 near as I recollect, about % or % inch in diameter. 

 Both upper and lower, being of transparent glass, 

 could be seen through, to show that there was no 

 possible connection with the shaft. The lower or 

 step-box was, as seen, a large square plate of glass 

 firmly fixed in the base of the machine, with a hole 

 in its center to fit and receive the lower gudgeon; this 

 step-box was two separate plates of glass, the upper 

 square one secured to the base had the hole for the 

 gudgeon bored entirely through it; the lower plate 

 was solid, circular, and in close contact with the 

 upper; it was mounted in a revolving ring carried 

 by arms from a vertical shaft with regular boxes and 

 step, and driven by a train of spur wheels from the 

 clock-work, which kept it constantly revolving. The 

 lower wing gudgeon of the perpetual motion was 

 made of hardened steel, and highly polished, the 

 upper journal long enough to allow the shaft to be 

 sufficiently raised as to lift the lower one entirely out 

 of the step-box, and be examined. The end of the 

 lower gudgeon was ground off to so slight a bevel 

 that it could not be perceived, but the weight of the 

 upright with its platform and cars, in reality, only 

 rested on the outer edge of one side of it, and their 

 weight was not sufficient to cause adhesion sufficient 

 for the revolving glass to transmit its motion to them, 

 but when the leaden weights were placed on the 

 inclined beds of the carriages it would slowly start, 

 and soon get up to its normal speed; this slow starting, 

 taken in connection with the large space, giving the 



chance at all times to see through the glass boxes 

 made the deception complete, and as I have before 

 stated, was never discovered. 



The machine was enclosed in a glass case and when 

 the museum was in the old State House, or Independ- 

 ence Hall, it was in the care of old Moses, the profile 

 or silhouette cutter of the museum, whose duty was 

 to see that the clock work never ran down during 

 the hours of exhibition. He would open the case, 

 and allow inquiring visitors to remove and replace 

 the weights; he told of Redheffer asking this privilege, 

 then sitting for hours watching the machine running, 

 and all the time talking to himself, the gist of which, 

 as far as Moses understood, was, Lukens has hit it, 

 and proved my theory right. 



Lukens told of Redheffer having called on him, 

 and began by abusing him for having stolen his 

 invention, and robbing him of the income he made 

 by its exhibition; that people instead of going out 

 to Germantown, now all went to the museum. Lukens 

 reminded him that stealing and robbing were ugly 

 words that he would not allow, that then Redheffer 

 changed his tactics, and proposed a union of interests, 

 saying that he, Lukens, by skill and superior work- 

 manship, had accomplished what he was aiming to 

 do, and that by a union large sums of money could 

 be made. Lukens said he told him that he would 

 have nothing to do with money made in that way. 

 He had made the machine for Mr. Peale, and had 

 been paid for its cost and the time he spent on it, 

 and that was all he should ever make. They had 

 never claimed it to be a perpetual motion, but 

 simply a model of a machine that he, Redheffer, was 

 exhibiting as such. 



Redheffer persisted in expressing his belief that 

 Lukens had solved the question, and that there 

 could be no trick in the museum machine. Lukens 

 had said, "If you believe so, go back to the museum, 

 have Moses open the case, take off the weights, and 

 it will then stop; then reverse the carriages, replace 

 the weights, you will find it will start and continue 

 to run in the same direction it was running, directly 

 the opposite to what it should, if your incline loaded 

 static weights were the propelling power. If that 

 don't satisfy that the angle or inclination of the weights 

 has nothing to do with the running of the machine, 

 just load them onto the platform wheel in any position 

 you choose, and the thing will run just the same; 

 they make it run, and it won't run without them." 



I have never seen any published account of the 

 device Lukens adopted to carry on for so long a 



85 



