HORSE-BACK RIDING. 45 



The increase of temperature is especially remark- 

 able at the surface when it may be relatively high ; 

 but it is far from attaining the same degree in the 

 central organs, it is there scarcely perceptible. The 

 natural cavities are the parts to be examined, be- 

 cause their temperature approaches nearest to that of 

 the internal organs. By taking the average of the 

 results which have been furnished, we find : 



Temperature of the axilla increased 1° 



** mouth " o°.6 



The elevation of temperature is less, the nearer we 

 approach the centre, and it is probable that there the 

 increase would not be more than one or two tenths of 

 a degree. 



These phenomena do not persist after the exercise 

 has ceased, and the system returns after a certain 

 time to its normal condition. The frequency of the 

 pulse, however, is perceptible yet after half an hour 

 of rest, and sometimes even longer. 



3. Respiration. — Horse-back riding causes great 

 differences in respiration, as well as in the circulation. 



All gaits, however, do not have the same effect 

 upon it. The walk, for example, affects it very 

 slightly; with the trot and gallop it is far different. 

 We have already seen the action of the diaphragm. 

 Occupied in assisting the muscles of the abdominal 

 walls to confine the viscera and repress their move- 

 ments, shaken as they are by the shocks of the trot. 



