446 On the salutary Effects of Riding, 



the term gestation is employed by medical writers, as {t 

 general term comprehending riding on horseback, or in a 

 carriage, and although the merits of such motions, espe- 

 ciallythe former, were clearly noticed, and perhaps even 

 over-rated, by the discernment of Sydenham, I believe that 

 no explanation has yet been given, of the peculiar ad- 

 vantages of external motion, and am persuaded, that the 

 benefits to be derived from carriage exercise are by na 

 means in so hiffh estimation as they ought to be. 



Under the common term exercise, active exertion has 

 too frequently been confounded with passive gestation, and 

 fatiguing efforts have consequently been substituted for 

 motions that are agreeable, and even directly invigorating, 

 when duly adapted to the iitrength of the invalid, and the 

 peculiar nature of his indisposition. 



The explanation which I am about to offer of the effects 

 of external motion tipon the circulation of the bloo(ii5 is 

 founded upon a part of the structure observable in the ve- 

 nous system, the mechanical tendency of which cannot be 

 doubted. The valves v/hich are every where dispersed 

 ihrough those n'ssels, allow free passage to the blood, when 

 propelled forward by any motion that assists its progress; 

 but they oppose an immediate obstacle to such as have a 

 contrary tendency. The circulation is consequently helped 

 forward by every degree of gentle agitation. The heart is 

 supported, in any laborious efibrt that may have become 

 necessary, by some obstacle to its exertions ; it is assisted 

 in the great work of restoring a system, which has recently 

 strug-ffled with some violent attack : or it is allowed, as it 

 were," to rest from a labour, to which it is unequal, when 

 the powers of life are nearly exhausted by any lingering 

 disorder. 



In the relief thus aff'orded to an organ 8o essential to 

 life, all other vital functions must necessarily participate; 

 and the various offices of secretion, and assimilation, by 

 ■yvhatever means they are performed, will not fail to be pro- 

 moted during such comparative repose from laborious ex- 

 ertion. 



Even the powers of the mind itself, thotigh apparently- 

 least likely to be influenced by mere mechanical means, 

 are manifestly, and in many persons most immediately, 

 affected by these kinds of motion. 



It is not only in cases of absolute deficiency of power to 

 carry on the customary circulation, that the beneficial 

 effects of gestation are felt, but equally so when com- 

 parative inability arises from redundancy of matter to be 



propelled. 



