136 ANNUAL OF SCIENTIFIC DISCOVERT. 



effect of this test apparatus (which was afterward made more perfect 

 and independent of the table) is the corrective power it possesses over 

 the mind of the table-turner. As soon as the index is placed before 

 the most earnest, and they perceive as in my presence they have 

 always done that it tells truly whether they are pressing downward 

 only or obliquely, then all effects of table-turning cease, even though 

 the parties persevere, earnestly desiring motion, till they become 

 weary and worn out. No prompting or checking of the hand is 

 needed the power is gone; and this only because the parties are 

 made conscious of what they are really doing mechanically, and so are 

 unable unwittingly to deceive themselves. 1 know that some may say 

 that it is the cardboard next the fingers which moves first, and that it 

 both drags the table and also the table-turner with it. All I have to 

 reply is, that the cardboard may in practice be reduced to a thin sheet 

 of paper weighing only a few grains, or to a piece of goldbeaters' 

 skin, or even to the end of the lever, and (in principle) to the very 

 cuticle of the fingers itself. Then the results that follow are too ab- 

 surd to be admitted ; the table becomes an incumbrance, and the per- 

 son holding out the fingers in the air, either naked or tipped with 

 goldbeaters' skin or cardboard, ought to be drawn about the room, 

 &c. ; but I refrain from considering imaginary yet consequent results, 

 which have nothing philosophical or reasonable in them. 



Another form of index was applied thus : A circular hole was cut 

 in the middle of the upper board, and a piece of cartridge paper past- 

 ed under it on the lower surface of the board ; a thin slice of cork was 

 fixed on the upper surface of the lower board corresponding to the 

 cartridge paper ; the interval between them might be a quarter of an 

 inch or less. A needle was fixed into the end of one of the index 

 hay-stalks, and when all was in place the needle point was passed 

 through the cartridge paper and pressed slightly into the cork beneath, 

 so as to stand upright; then any motion of the hand, or hand-board, 

 was instantly rendered evident by the deflection of the perpendicular 

 hay-stalk to the right or left. 



I think the apparatus I have described may be useful to many who 

 really wish to know the truth of nature, and would prefer that truth 

 to a mistaken conclusion ; desired, perhaps, only because it seems to 

 be new or strange. Persons do not know how difficult it is to press 

 directly downward, or in any given direction against a fixed obstacle ; 

 or even to know only whether they are doing so or not ; unless they 

 have some indicator, which, by visible motion or otherwise, shall in- 

 struct them ; and this is more especially the case when the muscles of 

 the finger and hand have been cramped and rendered either tingling, 

 or insensible, or cold by long continued pressure. If a finger be 

 pressed constantly in the corner of a window frame, for ten minutes 

 or more, and then, continuing the pressure, the mind be directed to 

 judge whether the force at any given moment is all horizontal, or all 

 downward, or how much is in one direction and how much in the oth- 

 er, it will find great difficulty in deciding ; and will at last become al- 

 together uncertain : at least such is my case. I know that a similar 



