38 
POPULAR SCIENCE REVIEW. 
minute the index at the further end of the lever was seen to 
move. “ The movements were much smaller than in the 
former case, and were almost: entirely unaccompanied by the 
percussive vibrations then noticed.” The curves traced on 
smoked glass are then given, but as we are told that they are 
magnified, and not told how much, for any purposes of com- 
parison they are quite worthless. The whole of the obtained 
results, however, show clearly that the disturbances were very 
small. Let us now consider what in these experiments would 
be the effect of the accumulation of small motions. Everyone 
is aware of the tension which is caused by keeping the hands 
in a constrained position for even a short length of time. The 
hands tremble, and their motion could not but be communica- 
ted to any delicate membrane in their immediate vicinity, and 
this membrane would amplify them and transmit them through 
the lever to the smoked glass. The tremors may easily be too 
insignificant to be detected by other hands placed on them, but 
amply sufficient to agitate the membrane. Again, too, the 
mere presence of a heated body in the air must cause currents 
in that medium ; but the hand is a heated body, and if these 
currents be caused to circulate round a stretched membrane, 
some vibration of the latter is almost certain to occur. We 
by no means assert that the explanations we have advanced are 
the true explanations of what occurred, but we are surprised 
that causes of error so obvious should not have presented them- 
selves to the mind of any scientific investigator, and have been 
duly examined and eliminated. 
It was from this very unsatisfactory series of experiments 
that Mr. Crookes drew the following remarkable conclusion 
2 tie italics are his) : 66 These experiments confirm beyond doubt 
e existence of a force associated in some manner with the 
human organisation, by which force increased weight is capable 
of being imparted to solid bodies without contact.” It is, 
however, a canon of physical research laid down by Newton 
that no new cause should be devised to account for phenomena 
which may be sufficiently explained by causes already admitted. 
Until, therefore, it has been incontestably shown that these 
phenomena could not be produced by known causes, it is un- 
philosophical in the highest degree to explain them by the 
assumption of a hitherto unknown force. Again, we have 
seriously to complain of Mr. Crookes when he says that, just 
as in the case of Electricity, “ certain conditions are found to- 
be essential to the production and operation of Psychic Force, 
and unless these precautions are observed the experiment fails. 
The conditions required are very few, very reasonable,” &c., but 
he entirely omits to state what they are. Imagine a man of 
Science describing the extreme importance of conditions under 
