254 DR. A. RANSOME ON GRAPHICAL REPRESENTATION 



manner any error dne to the altered curvature of the spine 

 in respiration is avoided. 



It will be observed that the medium for receiving the 

 writing is fixed, so far as its relation to the pen is con- 

 cerned — that it is not a rotating cylinder, as in Dr. San- 

 derson's stetho-cardiograph, nor a travelling carrier, as in 

 Dr. Marey's sphygmograph. These devices are needed 

 when a record of the relative force and frequency of the 

 motions is required; but, on the other hand, the intro- 

 duction of this extraneous movement prevents the accurate 

 delineation of the actual track pursued, in the forward 

 and upward directions, by any point on the chest-wall. 

 By means of the instrument now described, this tracing 

 may be obtained without difficulty. 



The following curves are selected in illustration of the 

 results which have been obtained with the stethograph; 

 and, for the sake of affording a simple basis for compari- 

 son, they are in the present paper limited, for the most 

 part, to the movements of the ends of the third pair of 

 ribs. 



I. Movements in Health. 



In observations made with the three-plane stethometer, 

 it had been remarked that the forward motion of the rib 

 was most equable throughout the whole act of respiration, 

 and that in men the upward movement takes place chiefly 

 at the latter portion of the respiratory act, but that in 

 women and children this movement keeps pace with the 

 forward push. 



Figs, i and 2, from a healthy adult male, and figs. 12, 13, 

 14, and 15, from a woman and from a youth, entirely bear 

 out this statement. In the tracing No. 2, taken from the 

 right third rib of an adult male, it will be found that the 

 ordinates of the curve in the first half of its course are 

 0*9 inch of forward to 0*3 inch of upward motion, and in 



