16 
METEOROLOGY—ANCIENT HUMAN RELICS. 
Uncertainty of our Meteorological Knowledge. 
The invention of measures of heat, and of atmospheric 
moisture, pressure, and precipitation, is extremely recent. 
Hence, ancient physicists have left us no thermometric or 
barometric records, no tables of the fall, evaporation, and flow 
of waters, and even no accurate maps of coast lines and the 
course of rivers. Their notices of these phenomena are almost 
wholly confined to excessive and exceptional instances of high 
or of low temperatures, extraordinary falls of rain and snow, 
and unusual floods or droughts. Our knowledge of the 
meteorological condition of the earth, at any period more than 
two centuries before our own time, is derived from these 
imperfect details, from the vague statements of ancient histo¬ 
rians and geographers in regard to the volume of rivers, and 
the relative extent of forest and cultivated land, from the indi¬ 
cations furnished by the history of the agriculture and rural 
economy of past generations, and from other almost purely 
casual sources of information. 
Among these latter we must rank certain newly laid open 
fields of investigation, from which facts bearing on the point 
now under consideration have been gathered. I allude to the 
discovery of artificial objects in geological formations older 
than any hitherto recognized as exhibiting traces of the exist¬ 
ence of man ; to the ancient lacustrine habitations of Switzer¬ 
land, containing the implements of the occupants, remains of 
their food, and other relics of human life ; to the curious reve¬ 
lations of the Kjokkenmoddinger, or heaps of kitchen refuse, 
in Denmark, and of the peat mosses in the same and other 
northern countries; to the dwellings and other evidences of 
the industry of man in remote ages sometimes laid bare by 
the movement of sand dunes on the coasts of France and of 
the North Sea ; and to the facts disclosed on the shores of the 
latter, by excavations in inhabited mounds which were, per¬ 
haps, raised before the period of the Roman Empire. These 
remains are memorials of races which have left no written 
records, because they perished before the historical period of 
