Of all the wondrous changes which nature has wrought on the earth's crust, there is scarcely anything that will bear comparison with those which meet the eye of the traveller in volcanic regions. Of the two great agents in. Geological transformation—water and fire, the one moves us with admiration at the delicacy of its operations, the other strikes us with awe at the mightiness of its influences, and the rapidity of its work.

Few, if any, countries present ua with such remarkable or various manifestations of the potency of subterranean heat as Iceland. So much so, indeed, that it appears as though it were the acknowledged safety-valve, in this portion of our globe at least, through which the troubled contents of depths unknown may, on any emergency, find a ready vent.

Interest more than ordinary appears to have been taken of late in this most remarkable region. No less than six parties of tourists having, during the year before last, investigated the natural marvels of the island. One of these adventurers, Lord Dufferin, in a most interesting and amusing book, has given to the world a record of his travels. From his “Letters from High Latitudes” we propose to quote his graphic picture of the result of volcanic action, in producing a very remarkable and very manifest change in the aspect of the large tract of country to which that portion of hiB narrative refers.

But before we proceed to this, it may perhaps be useful to recal to the reader's recollection the two theories which have, up to the present time, been put forth with respect to the causes of internal heat, and hence to the origin of volcanic action in general.