After our visit to the caldera of the Peak, with its walls of rock bleached by steam, and by acid vapours permeating them for ages, we could better understand the remarkable internal whiteness of lunar volcanoes, as shown by our telescope at Alta Vista.

Some geologists have, indeed, denied that the features seen by astronomers in the moon are to be considered as volcanoes; but we who duly noted the gentle external slope of some of those circular pits, their cliffy internal descents, their flat floors, and their central peaks—had little doubt in our minds. Occasionally could be traced something much like a collection of stony lava streams; which even the Spanish attendants, when looking by permission into the telescope, would call a Malpays. Generally too would they describe what they saw, with the same terms that they employed, for volcanic features of the mountain whereon we stood.

Could we have found in the moon, that dynamic trace, which was so important in proving relative ages among the red and yellow lavas of Teneriffe, viz., glacier wrinkles in one, and surf-like waves in the other,—all sceptical doubts must vanish. But we failed, and this point is left to a larger telescope, more constantly employed in lunar physics, on this or some higher mountain.

Details of a larger sort, however, were multitudinously brought out by the Pattinson Equatorial; to such an extent, indeed, as to be hopelessly beyond my poor efforts, to record them usefully in the small portion of time, that was available each evening.