THE ATMOSPHERE AND FOG-SIGNALING. 685 



as to the then climate of Europe by thinking of that of the present 

 habitat of the elephant and rhinoceros. Even now the Bengal tiger 

 traverses Asia as far north as latitude 52, and the lion and tiger are 

 frequently met with when snow and ice are present. 



The tools and weapons of the man of this age were simple indeed, 

 but no mean skill was employed in their manufacture and use. Even 

 with our many and marvelous inventions, one of us, cast away upon 

 some uninhabited shore, could hardly manifest more self-helpfulness. 

 And the manner in which the dead were buried one of the common 

 modes of expressing a race's faith in a future life shows the possession 

 of some degree of spiritual development. 



Such are " the earliest traces of man in Europe," the slight, sparse 

 indications of his existence in the Tertiary or next preceding formation 

 excepted. These traces of man in the Diluvium belong to the period 

 geologically the most recent indeed, yet even it is separated from our 

 own time by a gulf of many thousands of years. The rhinoceros, 

 primitive ox, giant-elk (Megaceros Hibemicus), and cave-bear, are prom- 

 inent among the contemporaries of this primitive man, but the char- 

 acteristic animal of the time was the mammoth. Hence the name of 

 the first age of Man the " Age of Mammoths." 



We will vainly seek in this earliest man for evidences of that crea- 

 turely perfectness which, according to the common view, he must have 

 inherited from his first parents in paradise the charming paradise of 

 Genesis, of art, and of poetry. For the geologist, the fruits of the 

 truly paradisaic epoch grew in a far remoter past, when Europe was 

 adorned with the palm and cinnamon-tree, and all the exuberant vege- 

 tation of the middle Tertiary period, whence our peat-beds are formed ; 

 when, instead of man, the ape, or possibly a man not much superior to 

 the ape, stood at the head of God's earthly creatures. 



Having answered the question as to man's first traces in Europe, 

 we might now bring our treatise to a close. But, to gain an adequate 

 notion of the antiquity of our race, and of its progress during the 

 successive ages, we proceed to a cursory review of the succeeding eras 

 of prehistoric human existence. 



THE ATMOSPHERE IN RELATION TO FOG-SIGNALING. 



By JOHN TYNDALL, LL.l)., F.E.S. 



II. Action of Hail and Rain. 



IN the first part of this article it was demonstrated that the optic 

 transparency and acoustic transparency of our atmosphere were 

 by no means necessarily coincident ; that on days of marvelous optical 

 clearness the atmosphere may be filled with impervious acoustic clouds, 



