214 -H. Helmholtz on the Interaction of Natural Forces. 



m 



In opposition to this it has been utged, that here in Prussia 

 the German knights in former times cultivated the vine, cellared 

 their own wine and drank it, which is no logger possible. From 

 this the conclusion has been drawn, that the heat of our climate 

 has diminished since the time referred to. Against this, how- 

 ever, Dove has cited the reports of ancient chroniclers, according 

 to which, in some peculiarly hot years, the Prussian grape pos- 

 sessed somewhat less than its usual quantity of acid. The fact 

 also speaks not so much for the climate of the country as for the 

 throats of the German drinkers, 



But even though the force store of our planetary sj^stem is so 

 immensely great, that by the incessant emission which has oc- 

 curred during the period of human history it has not been sensi- 

 bly diminished, even though the length of the time which must 



flow by, before a sensible change in the state of our planetary 

 system occurs, is totally incapable of measurement, still the in- 

 exorable laws of mechanics indicate that this store of force, 

 which can only suffer loss and not gain, must be finally ex- 

 hausted. Shall we terrify ourselves by this thought? Men are 

 in the habit of measuring the greatness and the wnsdom of the 



universe by the duration and the profit which it promises to their 



own race; but the past history of the earth already shows what 

 an iDsignificant moment the duration of the existence of our 

 race upon it constitutes. A Nineveh vessel, a Roman sword 

 awakes in us the conception of grey antiquity. What the muse- 

 ums of Europe show us of the remains of Egypt and Assyria 

 we gaze upon with silent astonishment, and despair of being able 

 to carry our thoughts back to a period so remote. Still must 

 the human race have existed for ages, and multiplied itself before 

 the pyramids of Nineveh could have been erected. We estimate 

 the duration of human history at 6000 years; but immeasurable 

 as this time may appear to us, what is it in comparison with the ■ 

 time during w^hich the earth carried successive series of rank 

 plants and mighty animals, and no men; during which in our 

 neighborhood the amber-tree bloomed^ and dropped its costly 

 urn on the earth and in the sea; when in Siberia, Europe and 

 forth America groves of tropical palms flourished; where gi- 

 gantic lizards, and after them elephants, whose mighty remains 

 we still find buried in the earth, found a home? Different geol- 

 ogists, proceeding from different premises, have sought to esti- 

 mate the duration of the above creative period, and vary from 

 a million to nine million years. And the time during which the 

 earth generated organic beings is again small when we compare 

 it with the aws durinsr which the world was a ball of fused 



O"""- *"o 



rocks. For the duration of its cooling from 2000° to 200^ Cen 



tigrade, the experiments of Bishop upon basalt show that about 



850 millions of years would be necessary. And with regard to 



