Page:Voyage in search of La Perouse, volume 1 (Stockdale).djvu/62

52 contact with the urfaces of bodies, affords a very atisfactory explanation of this plendid phenomenon. It exemplifies, upon a large cale, a fact well known to natural philoophers; namely, that when the rays of the un are made to pas through a mall hole in the window-hutter of a darkened chamber, o as to fall upon any object within it, they repreent the outlines of the object in all the various colours of the rainbow, by being collected with a prim and thrown upon a white heet of paper.

We now had to cros a prodigious heap of pumice-tones, amongt which we oberved very few vegetables, and thoe in a very languihing condition. The partium was the only hrub that could upport itelf in thee elevated regions. It was very troubleome walking upon this volcanic oil, as we unk into it up to the middle of the leg. We found ome blocks of pozzolana paringly cattered among the pumice-earth.

At nine o'clock in the evening we took up our abode for the night in the midt of the lava. Some large fragments that we found, were our only helter againt the eat wind, which blew with coniderable violence. The cold was very intene at this height, where nature has not conulted the convenience of travellers, as very little wood is found here; o that the canty fuel that we