148 SEC. 4. KINEMATICS, STATICS, AND DYNAMICS. 



536. Gyroscope, demonstrating the effects of revolution and 

 of rotation, the two ways of turning round. Henry Perigal. 



537. Gyroscope, demonstrating that revolution alone will 

 account for our always seeing the same face of the moon. 



Henry Perigal. 



538. Selenoscope, to demonstrate the kinematic effects of 

 the three hypotheses of the moon's motion, as a satellite of the 

 earth. Henry Perigal. 



539. Kinescopes, illustrating the laws of compound circular 

 motion, by ocular demonstrations of their representative curves, 

 shown by bright beads revolving with great rapidity. 



Henry Perigal. 



539a. Pendulum Apparatus, for the graphic representation 

 of the combination of rectangular and non-rectangular vibrations, 

 with illustrative plates. 



Institute for Physical Science of the University of Halle, 

 Professor Knoblauch. 



An apparatus for the graphical representation of two simultaneous oscilla- 

 tions inclined to each other. 



To a table are fastened the bearings of two pendulums, the oscillation- 

 planes of which are permitted to change their angle of inclination. One of 

 these pendulums transmits its motion to a horizontal bridge, the other to a 

 writing pen which moves exactly above the bridge. The oscillatory directions 

 of the bridge and the writing pen are the directions of the combined. velo- 

 cities. The curve the pin traces on the oscillatory bridge is to be con- 

 sidered as the trajectory of a point moving on a plane at rest under the 

 simultaneous oscillations of the pin and the bridge. 



This trajectory is recorded either by the motion of a steel pin over a piece 

 of sooted paper, or on white paper by a narrow-pointed glass tube filled with 

 aniline ink. 



If the weights on the pendulums are displaced the proportion of their 

 oscillatory movements is altered ; every difference of phase is obtained by 

 an appropriate choice of the time, one pendulum beginning to move after the 

 other. In this way the apparatus produces the greatest variety of geome- 

 trical figures. 



The traces accompanying the apparatus may serve as specimens, which 

 were drawn by the apparatus. 



A more exact and scientific explanation is to be found in the " Zeitschrift 

 " fur die gesammten Naturwissenschaften von Dr. C. Giebel," Bd. XIV., 

 October 1875. 



The apparatus has been designed by P. Schcenemann in the Royal Semi- 

 nary of Dr. Knoblauch, Professor of Physics at the University of Halle, and 

 has been executed for the physical science cabinet of the University by 

 Kleemann, mechanical engineer (Halle, Mauergasse 6). 



539b. Compensation Pendulum. 



Rohrbeck and Ltthme, Berlin. 



