VI. FALLING BODIES AND PROJECTILES. 153 



of the resultant of the atmospheric resistance will pass either ahove or below 

 the centre of gravity of the projectile, without, however, altering the position 

 of the centre of gravity itself. The vane can be turned on its axis, or be 

 removed and replaced by a double vane C 1 with the two flat surfaces placed at 

 right angles to each other. 



The following experiments can be made with this apparatus : 



1. Stability of the Axis of Rotation. 



The apparatus is put in motion to swing in a curve of five meters length by 

 taking hold of the vane and pulling it backwards, and then allowing it to drop. 

 If the projectile does not rotate, it easily turns over and will deviate from its 

 course by very slight causes ; if it rotates, it will remain parallel with its axis. 

 The vane must be given a neutral position in regard to the atmospheric 

 resistance. 



2. Lateral Motion. 



The apparatus is made to rotate to the right by the vane C being placed in 

 an upward position, when the point in flying forwards will revolve to the right. 

 If the direction of the rotation, or the position of the vane, be altered to the 

 opposite course or direction, the point will revolve towards the left. If both 

 are changed, the rotation will keep in the direction to the right. 



3. Lateral Deflection. 



The single vane C is replaced by the double vaue C 1 , the flat surfaces of 

 which being placed in a vertical and horizontal position, the proceeding then 

 is the same as described before. 



Instead of the lateral motion, a parallel lateral deflection will be the result. 



The latter experiment corresponds to the actual motion of the projectiles. 

 The greater degree of velocity being equalized by the larger surface of the vane 

 exposed to the atmospheric resistance. 



682. Rotation Apparatus for determining the effect 

 of Atmospheric Resistance on bodies of different shapes, 

 particularly on projectiles. Constructed by Theodor Baumann, 

 junior, Mechanical Engineer, Berlin. 



Professor Dr. E. E. Kummer, Berlin. 



(See " Abhandl. der Konigl. Akademider Wissenschaften in Berlin, 

 1875 "; " Uber die Wirkung des Luftwiderstandes," by E. E. Kummer.) 



547. Simple and Inexpensive Form of IVTorin's 

 Machine for demonstrating the law of falling bodies. It can be 

 made by an ordinary carpenter, at a moderate price, made by the 

 exhibitor. Dr. Stone. 



548. Apparatus by General Morin for the experimental 

 demonstration of the laws of falling bodies. 



M. Digeon, Paris. 



549. Attwood's Machine with water clock attached. 



The Council of the Yorkshire College of Science, Leeds. 



The time is measured by a water clock, the orifice of which can be opened by 

 means of a lever moving under the influence of an electro-magnet. The weights 

 are supported by a thread grasped by a pair of iron pincers, which are kept shut 

 by a spring, but can be opened by means of another electro-magnet included in 

 the same circuit as that attached to the water clock, so that the water begins 



