482 C. R. BARDEEN 



Table A gives figures for childhood and youth. Table B 

 gives figures for adults at three ages, 20, 30, and 50. In making 

 use of these tables one compares the parellel ray silhouette area 

 of the heart of the individual under consideration (a) with the 

 silhouette area given by the table as normal for a person of the 

 individual's weight and (b) with the silhouette area normal for 

 a person of the individual's height, sex and age being taken 

 into consideration. If the silhouette area is normal for weight or 

 for height or is intermediate between the two we consider that 

 the heart is one of normal size. If the heart volume correspond- 

 ing to the silhouette area is more than 10 per cent too large 

 both from the standpoint of height and of weight we consider 

 that it is disproportionately large. If it is correspondingly 

 small both from the standpoint of height and of weight we con- 

 sider it disproportionately small. Our own practice is thus to 

 estimate cardiac size in percentage of variation of volume from 

 that assumed as normal for height and from that assumed as 

 normal for weight. For instance we will suppose that a man 30 

 years of age 5' 10" tall and weighing 150 pounds shows a heart 

 silhouette area (reduced about 6 per cent to allow for divergence 

 of rays if a radiograph is used) of 120 sq. cm. From table B 

 we find that an area of 120 sq. cm. corresponds to a volume of 

 696 cu. cm. For a weight of 150 lbs. we should expect a volume 

 of 723 cu. cm. In a man 5' 10" tall at 30 years of age we should 

 expect a volume of 768 cu. cm. The heart of the individual 

 under consideration is therefore 27 cu. cm. or 3.7 per cent below 

 the standard from the standpoint of weight, 72 cu. cm. or 9.1 

 per cent below the standard for height. A slight variation of 

 this kind is within the limits of error of the method used and the 

 heart would be considered of normal size. 



In conclusion I desire to thank the members of the staffs of 

 the departments of anatomy, physiology and clinical medicine 

 and Prof. Max. Mason of the department of physics for valuable 

 aid in carrying out the investigations described in this paper. 



