of Clock Pendulums. 79 



"I had to speak on this subject at the Academy, on the 

 occasion of a communication from its correspondent, Monsieur 

 Sequin, — known by the important invention of tubular boilers. 

 It was my duty to speak as I did • but I cited old experiments 

 by Ellicott, clockmaker, mentioned in the Philosophical Transac- 

 tions, which made the greatest analogy with the admissible 

 accounts given of turning tables. 



" What is apparently most extraordinary and most difficult to 

 explain in the phenomenon of the tables, is the circumstance that 

 by means of, it may be said, infinitely small impulses, impressed 

 by the finger on the mass of wood of which the table consists, a 

 very considerable degree of motion should at length be imparted 

 to the table. "Well, then, I would remark that in Mr. Ellicott's 

 experiments, two pendulum clocks, enclosed in separate cases, 

 were suspended from a wooden plank affixed to the same wall, at 

 a distance of 23^ English inches from each other. 



"At first, only one of these two clocks was going. The second 

 clock was at rest. After a certain time, this second clock was 

 found to have been set going by the imperceptible vibrations trans- 

 mitted to its pendulum from the pendulum of the first clock, 

 through the medium of the intervening solid bodies. A very 

 singular circumstance is that, after a certain time longer, while 

 the pendulum of the second clock (the one which had at first 

 been at rest) vibrated in the largest arc which the construction 

 of the clock would permit, the pendulum of the first clock, the 

 one which at first was the only one going, had arrived at a state 

 of entire rest. 



"I will not enlarge upon the deductions which may be drawn, 

 and which really have been drawn, from the facts just mentioned, 

 because my object has only been to show that there already 

 existed in science, instances of communicated motion analogous 

 to those which have recently been presented by turning tables, 

 and of which the explanation does not require any of those 

 mysterious influences to which recourse has been had in the case 

 of the tables." 



I have quoted the foregoing Essay, which (with such an author) 

 is certainly entitled to respect ; not with a view to discuss or 

 overturn an opinion upon the question of "table turning," but 

 because it renders more complete and interesting the results of 

 those investigations which I am about to present to you. 



And here I may observe that my own experiments have been 

 carried on without any knowledge of those made by Mr. Ellicott, 

 beyond the reference made to them by M. Arago. Indeed, it is 

 only since I completed my own experiments, that I succeeded in 

 finding a detailed account of the others in the Philosophical 

 Transactions for the year 1739, and it is remarkable that whilst 

 the actual results arrived at in both cases are very similar, yet, so 



