438 C. R. BARDEEN 



graphic data of Dietlen ('07) on 187 men and 74 women, of 

 Schieffer ('07), on 123 men, of Veith ('08), on 80 orphan boys in 

 the prone position, 25 orphan boys in the sitting position and 

 25 school boys and 25 school girls in the sitting position. I have 

 also compared with these data data from Claytor and Merrill 

 ('09), based on the formula suggested by these authors that the 

 area of the heart shadow equal 70 per cent of the product of the 

 long diameter of the heart shadow by the transverse diameter. 

 These data relate to 37 men and 54 women. For the purpose of 

 comparison I have included similar estimates based on 156 of the 

 men studied by Dietlen and on 100 men studied by Otten ('12). 

 With these x-ray studies we have combined a direct study of the 

 heart contour in the dissecting room by means of drawing on a 

 glass plate so that the outline of the drawing is perpendicular to 

 the contour of the heart.- 



From this study of the relation of the size of the heart silhouette 

 to the body weight the following formula was determined: 



where 



B = weight of body in kilograms. 



H = area of heart silhouette in square centimeters. (Bardeen 

 '16). 



The values for body weight corresponding to a given area of 

 heart silhouette in tables A and B are based upon this formula. 

 For the sake of simplicity the weight is given in round numbers in 

 kilos and half kilos for body weights above 12.6 K.; in even 

 pounds for 19 pounds and above. 



The following tables show the average percentage of divergence 

 of the different groups of cases studied from the standard. 



The average percentage of divergence is determined as follows : 

 The heart silhouette area of each individual in the group is com- 

 pared with the area estimated to correspond with the body weight 



2 This is accomplished by means of an arc lamp, lenses and a mirror which 

 throws parallel rays of light from above through a glass plate so that the shadow 

 of a pencil point may be followed about the margin of the heart as the outline 

 is sketched on the glass plate. 



