Chap, xviii.] THE PANTOGRAPH. 187 



foot on the ground. It communicates with a recording 

 tambour of the usual form projecting on to the surface 

 of a revolving cylinder which the man carries in his 

 hand. The contacts of each foot are recorded side 

 by side on the same cylinder from a tambour in the 

 sole of each shoe. The man has also on his head a 

 tambour which transmits the vertical oscillation of his 

 body. Similarly Marey has adapted the apparatus for 

 recording the movements of a bird's wing in flight. 

 Modified forms of the apparatus have also been made 

 for registering the movements of the heart, of the 

 pulse, of the breathing. It is easy to understand also 

 how, by means of a series of tambours, disposed at in- 

 tervals along the course of an elastic pipe, informa- 

 tion may be obtained of the propagation of a wave 

 through the fluid which fills the pipe, and of the 

 differences in the characters of the wave when the pipe 

 ends in a wide or in a constricted opening, or when 

 the opening is entirely blocked. The apparatus may 

 also be adapted to the frog-plate of Marey, and the 

 muscle of the frog attached by its tendon to the short 

 lever of a receiving tambour, the registering one being 

 some distance away. An ingenious combination of 

 two tambours has been made by Marey for the 

 purpose of combining two movements in one tracing. 

 The arrangement is called the PANTOGRAPH. The two 

 tambours are placed at right angles to one another, 

 and their levers, jointed in a way to permit it, join 

 one common lever whose point is in contact with the 

 blackened surface on which the tracing is made. 

 Two such groups with their communicating tubes 

 form the pantograph. The lever of one group may be 

 made to pass over a series of curves, or to describe 

 circles, and so on, and the movement will be faith- 

 fully reproduced by the lever of the other group. By 

 means of this arrangement any figure may be repro- 

 duced, in its natural size, enlarged or reduced. 



