888 Experimental Investigation of Talle- Moving. [1853. 



interfere with any of the results expected by the table-turner, 

 for both the bundle of plates spoken of and single cards 

 had been freely moved on the tables before ; but now that 

 the index was there, witnessing to the eye, and through it 

 to the mind, of the table-turner, not the slightest tendency to 

 motion either of the card or of the table occurred. Indeed, 

 whether the card was left free or was attached to the table, all 

 motion or tendency to motion was gone. In one particular 

 case there was relative motion between the table and the 

 hands : I believe that the hands moved in one direction ; the 

 table-turner was persuaded that the table moved from under 

 the hand in the other direction : a gauge, standing upon the 

 floor, and pointing to the table, was therefore set up on that 

 and some future occasions, and then, neither motion of the 

 hand nor of the table occurred. 



A more perfect lever apparatus was then constructed in the 

 following manner : Two thin boards, 9^ inches by 7 inches, 

 were provided ; a board, 9 inches by 5 inches, was glued to the 

 middle of the underside of one of these (to be called the table- 

 board), so as to raise the edges free from the table ; being placed 

 on the table, near and parallel to its side, an upright pin was 

 fixed close to the further edge of the board, at the middle, to 

 serve as the fulcrum for the indicating lever. Then four glass 

 rods, 7 inches long and in diameter, were placed as rollers on 

 different parts of this table-board, and the upper board placed 

 on them ; the rods permitted any required amount of pressure 

 on the boards, with a free motion of the upper on the lower to 

 the right and left. At the part corresponding to the pin in 

 the lower board, a piece was cut out of the upper board, and 

 a pin attached there, which, being bent downwards, entered 

 the hole in the end of the short arm of the index lever : this 

 part of the lever was of cardboard ; the indicating prolongation 

 was a straight hay-stalk 15 inches long. In order to restrain 

 the motion of the upper board on the lower, two vulcanized 

 rubber rings were passed round both, at the parts not resting 

 on the table : these, whilst they tied the boards together, 

 acted also as springs, and whilst they allowed the first feeblest 

 tendency to motion to be seen by the index, exerted, before the 

 upper board had moved a quarter of an inch, sufficient power 

 in pulling the upper board back from either side, to resist a 



