July 3 i, 1884J 



NA TURE 



3i9 



the structure of the human trunk and that of the 

 seat, more particularly in railway carriages, designed for 

 its accommodation. In a sitting posture the pelvis has 

 for its sole function the support of the upper part of the 



body. The spinal column, however, is inserted in the 

 pelvis, not in the form of a straight line but of a curve 

 (Fig. 1). This inflection on the part of the backbone, 

 while adding to the mobility of the trunk, imposes on it 



the necessity of a continual balancing movement, the 

 centre of gravity being shifted every time the head and 

 thorax sway to one side or the other. Such balancing 



movement is necessarily also attended by a certain ex- 

 penditure of energy. To allow the upper part of the 

 body to remain comfortably at rest there must be sup- 



ports for the back, the shoulders, and the head. .^So far 

 as these are wanting, the body will tend of itself,"' unless 

 counteracted by an effort of will and nervous force, to 

 bend forward, till at last the forehead finds the knees to 

 lean on. The position of the body in sitting is all 

 the easier, and its rest all the more complete, the 

 more decided is the inclination of the back of the seat 

 and the more obtuse is the angle formed by the trunk and 



the thighs. Seats such as the dormeuses realise the most 

 favourable conditions in this respect. 



Fig. 2 represents a man comfortably seated and 

 propped. The back of the seat supports him principally 

 under the shoulder-blades, offers the chest a depression 

 to sink in, and altogether keeps the upper part of the 

 body in a free and easy position. Fig. 3 shows the same 

 person in a similar position, but with his head resting 



Ju 1 1 



Fig. 8. 



behind. In both these figures the back of the seat is 

 seen exactly in profile, and to the writer of the article 

 such seems the construction which is most convenient in 

 railway carriages. 



Fig. 4, on the other hand, represents the profile of a 

 man seated as passengers are in many of our actual 

 first-class carriages. His position is perceived to be a 

 forced one in contrast with that just noticed, and alto- 



