THE SCANDINAVIAN MOUNTAINS. 109 
this difference may be, we can nevertheless hope, that it will 
be possible at some future time to discover the cause; al- 
though the theory which I now have the honour to bring for- 
ward is not accurately confirmed. The phanomenon, at least, 
appears not to be the result of a condition of elements which 
has been as changeable as the wind. 
What I have hitherto had the honour to adduce, are for the 
most part facts alone. They have been collected with care, but 
require however to be confirmed by observations repeated with 
more nicety, in every place where opportunity offers, even 
out of the route where observations have been already made, 
before any satisfactory conclusion can be drawn. I might here 
conclude this treatise ; but with a hope that a more general in- 
terest may be taken in the subject, I wish to state some 
points of view in which I consider it ought to be regarded, and 
which possibly may serve as a guide to future observers of this 
phenomenon. This shall be done in the following paragraphs ; 
nevertheless I request that every one who may give it his atten- 
tion, and commence making observations, will take care in every 
place to search for the normal furrows. He must not, however, 
spare himself the trouble of observing all the side-furrows, and 
carefully noting them ; for it often happens that on the same 
spot one cannot exactly see those which are side-furrows if they 
do not touch a lesser hill: nor until after the investigation of 
the tract, when from some hill clear of wood the whole can be 
overlooked, is it easy to say which furrows are normal. 
Having now concluded the description of my observations 
on furrows, may I be permitted to accompany them with a more 
explanatory detail of the hypothesis to which they have given 
rise, and which served me as a clue in pursuing my investiga- 
tions? The geologist cannot proceed in the way pursued in 
other sciences ; he can only bring forward the results of what has 
been; but what the cause is he may guess, without coming to 
other or greater certainty than that which is gained by increased 
probabilities for the hypothesis. 
Geology, as a perfect science, would be nothing more than a 
history of the changes which the surface of the earth has under- 
gone from the commencement of her revolving round the sun. 
But this history is irrecoverably lost ; it has been written by no 
human hand, and no nation has been found which could trans- 
plant its traditions. We must thus, from what we see, endea- 
