72 HiE 111 MAX FRAME. 



certainly present: or, on the other hand, should it have permanently sunk 

 to 50 beats, it is but too probable that the source of the circulation, the 

 heart itself, is laboring under some incurable disease, or that some other 

 of the springs of life is irremediably injured. Supposing, again, the pulse 

 to be 72. each beat ought to occur at an interval of five* sixths of a 

 second; but should any deviation of the rhythm be perceived, the pulse 

 is said to be irregular. The varieties of the irregularity are infinite, but 

 there is one so remarkable as to deserve particular mention. It will 

 happen sometimes, that the interval between the two beats is so much 

 longer than expected, that it would seem that one beat had been omitted; 

 in this case the pulse is said to be an intermittent one. When the 

 action of the heart is irregular, the beat of the pulse is so also; but it will 

 occasionally happen, that the latter irregularity takes place without the 

 former one, from some morbid cause existing between the heart and the 

 wrist. Sometimes there is no pulsation at all perceptible at the wrist 

 this may proceed from so great a langour of the circulation, as not to be 

 felt at the extremities, or from the radical artery (the one generally felt) 

 being ossified, or from an irregular distribution of the arteries of the 

 fore arm. 



AVERAGE DURATION OF HUMAN LIFE. 



Nothing is more proverbially uncertain than the duration of human 

 life, where the maxim is applied to an individual ; yet there are few things 

 less subject to fluctuation than the average duration of a multitude of 

 individuals. The number of deaths happening amongst persons of our 

 own acquaintance is frequently very different in different years, and it 

 is not an uncommon event that this number shall double, treble, or even be 

 many times larger in one year than in the next succeeding. If we consider 

 larger societies of individuals, as the inhabitants of a village or small 

 town, the number of deaths is more uniform : and in still larger bodies, as 

 among the inhabitants of a kingdom, the uniformity is such that the 

 excess of deaths in any year above the average number seldom exceeds a 

 fractional part of the whole. In the two periods, each of fifteen years, 

 beginning at 1780, the number of deaths occurring in England and Wales 

 in any year did not fall short of or exceed the average number of one 

 thirteenth part of the whole, nor did the number dying in any year differ 

 from the number of those dying in the next by a tenth part 



