Abstract
Thoracic and abdominal surface areas have been measured by planimeter on 340 photogrammetric somatotype photographs of 15 boys of the Harpenden Growth Study followed at regular intervals from 3 to 20 years of age. Mean distance and velocity curves are given, estimated by Patterson's method for extracting maximum information from mixed longitudinal data. Both areas showed a marked adolescent growth spurt with the age at peak coinciding with the age of peak height velocity of the same children. The correlation coefficients between thorax and abdominal surface areas rose from an average of about 0-3 at ages 5-8 to 0-5 at ages 9-12 and 0-7 at ages 13-19. Trunk index (thorax/abdomen area) fell gradually with age from 5 to 9 and thereafter remained constant.