45, CORNHILL, E.C., AND 122, REGENT STEEET, W., LONDON. 



495 



FIG. 3073. 



FIG. 3072. 



FIG. 3071. 



3070 The Gyroscope, a modification of Bohnenberger's machine, introduced by 



M. Foucault, is an instrument arranged to illustrate the following 



principles : 



That inertia is a property of matter in motion, as well as of matter at rest. 

 That orbital and axial motion are intimately related, and that the speed of 



one may affect or regulate the other. 

 That the state of unstable equilibrium in which many bodies remain is to be 



explained by the fact of their rotation. 



That bodies in motion endeavour to maintain their original plane of rotation. 

 That the power of resisting or overcoming the force of gravity possessed by 



shots fired from Armstrong's gun is due to the gyratory motion given to 



them by the peculiar formation of the gun. 

 It will also illustrate the precession of the Equinox. 



Each. 



3071 Gyroscope, the simple form, with a stand (fig 3071) 1 10 6 



3072 Ditto, of the best and most complete form 



(as fig. 3072), in mahogany cabinet .... 3 10 



All other Instruments, Models, or Apparatus required to illustrate the Sciences for 

 Educational or Lecturing purposes, constructed to order. 



FOUCAULT'S EXPERIMENTS WITH THE GYROSCOPE. 



3073 The following illustrated description of the Gyroscope from a paper read by M. 

 Foucault, before the British Association, " Nouvelles Experiences sur le Mouvement de la 

 Terre au Moyen du Gyroscope," is from the Civil Engineer and Architects' Journal. 



