to a moderate stride, in the line of the effort which is foreseen to require 

 resistance. 



There is some resemblance to standing, in the attitudes of kneeling 

 and sitting. 



In the first, the weight of the body bears upon the knees, and we must 

 bring back the body, to throw the centre of gravity over the middle of the 

 legs. Accordingly, if we have nothing before us to lean on, this posture 

 is extremely distressing, and we cannot long keep it on. I have said, in 

 another work, that genuflexion rendered monks very liable to hernia; the 

 abdominal viscera being pushed against the anterior and lower part of 

 the abdomen, by the throwing back of the body. 



In sitting, the weight of the body bearing on the tuberosities of the 

 ischia, there is much less effort required than in standing on the feet. 

 The base of support is much larger ; and when the back leans, almost 

 all the extensor muscles employed in standing, are in action. 



CLXXXVI. Of Ike recumbent jiosture. Decubitus. All the authors 

 who, like Borelli, have treated professedly of the animal mechanism; all 

 the physiologists, who, like Haller, have set forth, in some detail, the me- 

 chanism of standing, and of progression, have completely passed over the 

 consideration of the human body in repose, left to its own weight, in ly- 

 ing on an horizontal plane. The intention of the following observations 

 is to fill up this gap. Let us consider, at setting out, that lying on an 

 horizontal plane, is the only posture in which all the locomotive muscles 

 recover the principle of their contractility, exhausted by exertion. Stand- 

 ing whhout motion, has only the appearance of repose, and the unremit- 

 ted contractions it requires, fatigue the muscular organs, more than the 

 alternate contractions, by which the various motions of progression are 

 carried into effect. 



The human body, stretched on an horizontal plane, reposes in four po- 

 sitions ; as it lies on the back, the belly, or one or other of the sides". 

 The Latin tongue expresses the first two situations, by the terms supine 

 and prone*- It has no particular word for lying upon the sidef. 



Lying upon the right side is the most ordinary posture of sleep, in 

 which we rest most pleasantly, and longest together. There are very 

 few, except under constraint of some faulty organization, who lie on the 

 other side. This depends on two causes; when the body lies on the left 

 side, the liver, a bulky viscus, very heavy, and ill steadied in the right 

 hypochondrium, presses with all its weight on the stomach, and draws 

 down the diaphragm : thence ensues an uneasiness, which hinders long 

 continuance of sleep, or disturbs it with distressing dreams : then the 

 human stomach presents a canal in which the course of its contents is 

 obliquely directed from above downwards, and from left to right: the 

 right or pyloric orifice of the stomach is much less raised than its left or 

 cardiac orifice ; lying on the right side favours, therefore, the descent of 

 aliments, which to pass into the intestines, are not obliged to ascend 

 against their own weight, as they must, in lying on the left side, i hese 

 two anatomical causes exert their influence on the generality of men, and 

 if there are any who fall into the habit of lying on the left, one may safe- 



* Cubitus supinus, Plin. Cubitus pronus, Cicer. Cubare in faciem, Juven. Supinus 

 velpronus jucere. 



f Dextro vel laevo hterc cubare ; cubitus in hitus. Plin'". 



