DWARFS AND GIANTS. 



771 



(or fifteen thousand pounds), and elephants should move mountains. 

 We can not dispute the accuracy of the experiments or the calculations, 

 nor impeach the sincerity or judgment of the experimenter. The 

 facts are, moreover, conformahle to observations. A caterpillar in the 

 closed hand will make prodigious efforts to open his prison ; and 

 who has not seen ants carrying things three or four times as large as 

 themselves ? Various attempts have been made to escape the con- 

 sequences that were deduced from these experiments, but they still 

 stand, apparently defying criticism. Must we, then, resign ourselves 

 to beincc a hundred or two hundred times weaker than a beetle ? Are 

 insects really, in physical force, kings of creation ? 



Not yet. An important element has been neglected. No account 

 has been made yet of the time it takes the insect to perform its won- 

 derful feat. Whenever we raise a given weight to any height, by 

 whatever method, the labor performed is in proportion to the weight 

 multiplied by the height ; and this product always gives the measure 

 of that labor. The same product, under certain restrictions, furnishes 

 the measure of the force that is utilized in the work. A dog is not as 

 strong as a horse, but both animals expend precisely the same force in 

 raising a kilogramme a metre. Whatever the kind of work he may wish 

 to calculate, even though it be horizontal, it is always reducible to the 

 elevation of a certain weight to a certain height, and is in practice 

 measured by a formula of which these are the terms. 



While, however, the quantity of foi'ce that must be expended for a 

 determined work is invariable, this is not the case with the manner 

 in which that expenditure may be distributed. If I wish to strike a 

 single strong blow, I execute a quick movement. If my muscular 

 power is weak, I must have more time. It is possible, then, for time 

 to supply a deficiency of power. I can make such a substitution appli- 

 cable in two ways, by dividing the resistance, or by using a machine as 

 a lever, which, when everything about it is considered, is nothing more 

 or less than a device by means of which we replace power with time. 



Accurately to compare the strength of a May-bug with that of a 

 man, we must take into the account the time which the insect requires 

 to perform the work exacted of it. Suppose a horse harnessed to a 

 load of half his weight, and a May-bug drawing a tray fifty times as 

 heavy as itself : the beetle's load will be relatively a hundred times as 

 heavy as the horse's. But if the horse needs only a second to raise his 

 load a metre, while the insect takes a hundred times as Ions; to pro- 

 duce the same effect, then the efforts of which they are both capable 

 are proportionably the same. The case is the same, only the appear- 

 ance is changed, when the force is spent in maintaining the weight at 

 an equilibrium. 



In a similar manner we may account for the power manifested by 

 the insect which I cover with a board a hundred times as heavy as 

 itself, and which gets its head under the edge, raises it, and escapes. 



