86 MAMMALIA—-MAN 
The strength of man is very considerable, when matured by practice. 
We are assured that the porters of Constantinople carry burthens of not 
less weight than nine hundred pounds; and Mr Desaguliers tells us of a 
man, who by distributing a certain number of weights, in such a manner 
that every part of his body bore its share, was able to support a weight of 
two thousand pounds, in an upright posture. 
The strength of a man may Le still farther estimated by the continuance 
of his labor, and by the agility of his motions. Men who are exercised in 
rurning, outstrip horses, or at least continue their speed for a greater length 
of time. In a journey, also, a man will walk down a horse; and after they 
have proceeded together for several days, the horse will be quite tired, and 
the man will be as fresh as at the beginning. The royal messengers 
of Ispahan, who are runners by profession, go thirty-six leagues in fourteen 
or fifteen hours. Travellers assure us that the Hottentots outrun lions 
in the chase; and that the savages who hunt the elk, pursue with such 
speed this animal, which is as fleet as a stag, that they at last tire it down 
and take it. 
When the constitution of the body is sound, it is probably possible, by 
moderation in the passions, temperance, and sobriety, to lengthen out the 
period of tire for a few years. But even of this there seems an uncertainty. 
Men no doubt there are, who have passed the usual period of human exist- 
ence; and, not to mention Parr, who lived to the age of one hundred and 
fifty-two, and Jenkins, to that of one hundred and sixty-nine, as recorded in 
the Philosophical Transactions, we have many instances of the prolongation 
of life to one hundred and ten, and even to one hundred and twenty years 
Yet this longevity was occasioned by no peculiar art or management. On 
the contrary, it appears that the generality of such long livers were peasaats, 
accustomed to the greatest fatigues, huntsmen, or laborers; men, in fact, 
who had employed their whole bodily strength, and even abused it, if to 
abuse it be possible, otherwise than by continual idleness and debauchery. 
If, in the duration of life, there is any difference to be found, it ought 
seemingly to be ascribed to the quality of the air. In elevated situations, 
it has bern ovserved, there are commonly found more old people than in 
such as are low. The mountains of Scotland and Wales, of Auvergne and 
Switzerland, have furnished more instances of extreme longevity, than the 
plains of HoJland or Flanders, of Germany or Poland. In general, however, 
the period of human existence may be said to be the same in every country. 
If not cut off by accidental diseases, man 1s found to live to the years of 
ninety ora hundred. Beyond that date our ancestors did not live; nor hag 
it in any degree varied since the time of David. 
From a careful inspection of the registers of burials, in a certain number 
of country parishes in France, compared with the mortality of Paris, the 
following tab'e has been made out, of the probable duration of hurnan life 
