The Operation and Use of the Apparatus 



keeping our distance from the shore, and have no difficulty of 

 feeling our way into port. 



Plate No. i represents a vertical central section of the appar- 

 atus for producing the vibrations. The rotating disc is driven 

 at a uniform speed by an electric motor, so that the pitch of the 

 note sounded is always the same. The steam enters the central 

 pivot, passes through the balanced valve, and escapes through 



PLATE 2. Side Elevation of the Siren or Vibrator. 



expanding nozzles into the small end of the trumpet. The 

 balanced valve is opened and closed by means of a handle, as 

 will be seen ; the opening and closing of the valve also makes 

 and breaks electric circuits. 



Plate No. 2. A side elevation of the complete apparatus 

 on a greatly reduced scale. The trumpet, being of great 

 size, is supported by a wheel. The trumpet may be turned 

 in any direction without interfering with the supply of steam, 

 which enters through the centre of the pivot on which the 

 apparatus revolves. It is proposed to use this form for long- 

 distance work, but where it is desirable to spread the vibra- 



37 



