II. 



SPINNING MOVEMENT. 



I. The Mysterious Skinner ; Motion without 

 Apparent Cause. 



THE author once had occasion to test the air 

 of a room at various points for slight down- 

 draught and up-draught by some delicate and 

 sensitive test. For this purpose he devised 

 an appliance which, while it illustrates a point 



FIG. 5 CONSTRUCTION OF MYSTERIOUS SPINNER. 



of great and paradoxical interest, can be 

 readily made by anyone at home. Its con- 

 struction will therefore be described fully, so 

 as to ensure success. 



Draw lines A B and CD, as in Fig. 5, at 

 right angles to each other with pencil on a 

 piece of note-paper. Draw two others E F 



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