Sleep, however, came at last, but the cold soon awoke us, and by midnight the whole valley was covered with a thick coating of white frost, which glistened like snow beneath the pale moonlight. I had placed my thermometer close handy, so that I might observe it during the night, and I now found that it stood at 27°; at four o'clock it marked 22°; and at six o'clock, just before sunrise, it indicated exactly twelve degrees of frost. The plants around us were completely matted together with white incrustations; the icicles rose from the ground over an inch in length, and in a way that I had never seen before; the breath froze upon the moustache and beard; the manes of our horses stood erect, the bristles about their nostrils were transformed into needle-like icicles, and their backs were covered with a crisp, white coating of frost. It did not take us long to saddle up, although we experienced some little difficulty with the buckles, owing to our fingers being numbed with the cold; but once on our horses, we rode rapidly away from Tongariro, and just as the first ray of sunlight swept over the hills we gained the plains beyond, to begin the ascent of Ruapehu. FOOTNOTES: [Footnote 46: _Taniwha_, native name for a fabulous reptile supposed to inhabit deep water.] [Footnote 47: The exact position of Tongariro is-- Lat. 39° 9' 45" S. Long. 175° 38' 20" E.] [Footnote 48: Throughout the journey we found that the cold winds from the south invariably brought fine weather.] [Footnote 49: For _flora_ of Tongariro, _vide_ Appendix.] [Footnote 50: It is supposed by many that Tongariro and Whakari (White Island) are the only two remaining centres of active volcanic action in what may be termed the Australasian division of the Pacific. This in reality is not the case. The great volcanic belt which appears to extend through the Malay Archipelago may be said to stretch as far south as the New Hebrides. Thus on the island of Tanna there is an active volcano which attains to an altitude of 1500 feet above the sea. It is in a constant state of eruption, emitting vast volumes of smoke, with ashes and lava, from a crater 500 feet in depth. On the island of Ambrym, of the same group, there is likewise an active volcano, nearly equal in size to that of Tanna, while on the island of Vanikoro still further to the north, in the Santa Cruz group, there is a cone-shaped mountain in a constant state of activity. During a journey of exploration in the New Hebrides and other islands of the Coral Sea, the volcano of Tanna was ascended by the author, who read papers descriptive of the islands before the British Association, at its meeting held at the University of Glasgow in 1876.] CHAPTER XVII. ASCENT OF RUAPEHU. (_First Day._)