Art. XLVIII.—Some Notes on the Volcanoes of the Taupo District.
[Read before the Auckland Institute, 20th June, 1898.]
Tongariro is not a single mountain, but a highly complicated volcanic system. Models of it which I saw in the colony made it appear that Tongariro was one truncated cone, with the Blue Lake on its top, but obviously models of that nature must have bee a shaped by persons who never saw Tongariro from an elevated point—either from one of its tops or from Ngauruhoe.*
In the Survey Report of 1891, however, there was published a map of the summit of Tongariro which is practically correct. Unfortunately, I only obtained this plan after having visited Tongariro, and therefore was unable to compare it with nature on the spot. As far as my memory, my photographs, and my notes go the map is essentially exact. But I cannot recollect that part balled the “West Crater”—viz., a crater adjoining the North Crater (that is, the crater above Ketetahi), towards the south-west. There may be different reasons for my not recollecting it, and I do not intend to question its existence. I would not have even mentioned it had I not found that this West Crater is wanting not only in my memory, but also in Professor Thomas's sketch-map, published in the Transactions, vol. xxi. (1888), page 348.
[Footnote] * The only model with which I am acquainted in the colony is one that I myself made. The original is in the Colonial Museum at Wellington, and faithfully represents Ngauruhoe as a cone, and Tongariro in its proper multiplex volcanic form with the Blue Lake on its top. The volcanic range so well described by the learned author presents no great difficulties to the tourist, and frequent photographs have made it familiar to the general public—J. H., Ed.
The depression of the West prater, perhaps, is only a slight one, and was not counted as a crater proper by Professor Thomas and myself. The region in question must be visible from the highest point of Tongariro (about south-south-west from the North Crater) which I have visited; but I repeat that I cannot fully rely on my memory, on account of the astonishing intricacy of the Tongariro system.
The shape of the system, roughly, may be compared to, a huge horse-shoe, the axis of which is coincident with that of the volcanic zone. Its hollow is formed by the South Crater of the survey plan—a vast somewhat elongated basin, surrounded on all sides, except south-west, by steep ridges, the highest point of which is the summit proper of Tongariro. These ridges decrease rapidly in height towards the southwest, and the south-eastern side only reaches the foot of the cone of Ngauruhoe. The view from the trig, station, over the precipitous ridges, down into the sandy velvet-like bottom far below, and beyond the magnificent cone of Ngauruhoe, is extremely picturesque. The northern parts of the horse-shoe are much broader, and contain a considerable number of craters, which together form a rather extensive tableland. The most prominent of these craters are the North Crater (already mentioned) and the Blue Lake Crater (further east).
The map above mentioned shows that the eastern parts of Tongariro are rent open by deep and rather steep valleys, and that on the northern slope there are two active places—viz., the fumaroles and hot springs of Ketetahi on the slope of the North Crater, and Te Mari on the slope of the Blue Lake Crater. Te Mari is a small cinder-cone; and a short distance below it there is another crater, which, according to the map, contains a lake; but I have not seen this lake, as I did not venture too close to the rim of the crater, nor to Te Mari either, on account of the somewhat threatening degree of activity of the latter. Possibly the lake was there, but it was invisible from my standpoint.
Shortly after my arrival in New Zealand—in November, 1896—the newspapers reported that eruptions had taken place at Te Mari. I visited the volcanoes for the first time in December, 1896, and Ngauruhoe first of all. At that time Te Mari was always steaming furiously, and sometimes emitting dark, dense, brownish-grey clouds, the appearance of which indicated the presence of ashes.
On the afternoon of the 11th December, 1896, I found myself shrouded in mist and rain on one of the eastern ridges of Tongariro, and I heard distinctly, for some minutes, a continuous roaring and thundering in the direction of Te Mari.
On the evening of the 14th December, 1896, I was encamped on the northern slope of the North Crater, about an
hour's walking distance from and beneath Ketetahi. That day Te Mari was steaming less than it had done on the previous days, and scarcely more than Ketetahi; but the slightly bluish colour of its steam betrayed a somewhat higher temperature. But for this fact one might have thought the period of activity was almost at an end, and I little hoped that I should witness one of those eruptions of which I had so often heard or read. We were sleeping quietly in our camp when, at about half-past 12 o'clock, we were awakened by a thundering noise, and on going out of our tent we beheld a very remarkable spectacle—indeed, I afterwards heard that at Otakou the natives had already commenced leaving, and would have left altogether but for the short duration of the violent phase of the outbreak.
Against the starlit and cloudless sky stood a gigantic pillar of ash-bearing steam, broadening towards its summit, and overtopped by a detached roundish mass of the same appearance. Evidently the explosion had begun by a single shot, followed by a rest of some seconds. The pillar of steam—as ash-bearing and other volcanic clouds always are, as long as they are in ascending movement, hotter than the surrounding air—was of an exquisite cumulus character. This and its absolute opaqueness and dark colour gave it a strange appearance, almost like that of a solid body—an enormous stalagmite, as it were. But the most surprising sight was the wonderful display of different kinds of light phenomena. Whereas at no time had I seen the slightest fire - reflection above Te Mari, the lower parts of the steam column were now all aglow with a dark-red glare. A large number of what looked like bright sparks shot high up, and fell down in parabolic lines. There was going on, besides, a continuous play of electric lightning in the clouds, mostly, but not always, in the lower parts. I think there was on the average fully one lightning flash to the second. These lightning flashes did not differ from ordinary flashes except that they were mostly rather short; their being confined to one spot of the sky, and their wonderful frequency, made, too, a very curious impression. The thunder blended, together and formed a continuous roar, which, however, at our station was not deafening. But the most remarkable and interesting phenomenon had yet to come. The upshooting sparks (here I describe the immediate impression only, giving the explanation later on) by degrees became rarer, and the lightning also; and then there appeared large flames of a brilliant-blue hue, which mingled with the ascending steam—apparently floating, as it were, free in the air at some distance above the mouth of the crater. I estimated the height of the flames at about 100 ft.
About a quarter of an hour after its commencement the
eruption proper was over—the glare faded away, the sparks and the flames disappeared, and the lightning stopped. Now and then, at longer intervals, there were one or two flashes, but soon nothing was left but a great pillar of steam, and smoke that continued slowly to rise, and the top of which, losing its sharp rounded outline of a cumulus cloud, began to spread. Its height must have been very considerable, as it reached our zenith apparently—but only apparently, as we did not receive any ashes at our standpoint.
These observations were made from the camp mentioned above, on a perfectly clear night and with a very good binocular of 6-diameter enlargement, and therefore I am absolutely certain of my statements. There were at least four different light phenomena.—(1) The reflection of the incandescent matter on the steam; (2) what I called the sparks; (3) the electric lightning; and(4) the blue flames. Besides the latter, there seemed to be sometimes reddish flames; but this I cannot state with absolute certainty, as from a distance it is almost impossible even for an experienced observer to distinguish with any degree of certainty illuminated steam and supposed reddish flames.
The above-described eruption seems to me to be remarkable in more than one respect; it evidently was one of many similar eruptions which had been mentioned by the news-papers. One of the characteristics of Te Mari's activity, therefore, was its intermittency; but not its only one. What surprised me most was the display of incandescent matter during the violent phase only, whereas before and after nobody would have believed in the presence of red-hot magma, as, with the exception of that explosion—lasting about a quarter of an hour—no fire-reflection was visible.
What looked like and were described as “sparks” were the large number of red-hot boulders that were shot up. The impression was that the fusion was very imperfect, the magma very viscous, and scarcely as hot as that of Vesuvius, Etna, or Stromboli, not to speak of the white-hot and most perfectly molten lava of Hawaii. It is difficult to tell -why the magma, in the shape of reflection and red-hot stones, was visible only at intervals, for this probably has been the case at more than one eruption, as most of the newspaper reports state that there had been “fire,” and not only smoke, whereas during the long time between the short paroxysms Te Mari looked rather harmless, and little more than a lively solfatara.
As to the electric lightning, there is but little doubt that the source of electricity is the friction. This was the second time I had observed volcanic lightning, and in both cases it appeared in masses of ash-bearing steam; and the ashes were coarse, the single grains being about the size of a pin-head.
The ashes of the explosion I witnessed were collected at Waihohonu by Mr. Peters, from whom I obtained a small bottleful. A [European settler at Otakou told me that the lightning was seldom so lively as during the night of the 14th December, 1896, and that most of the ashes produced by Te Mari were very fine, and almost like flour. Perhaps, therefore, coarse ashes favour the development of electricity by increasing the friction.
As to the flames, I need not remind you that frequently flames in volcanoes have been described—and doubtlessly will be described—which were only illuminated steam or smoke. In popular descriptions, out of a hundred alleged flames ninety-nine are certainly not flames. Most excursionists to Vesuvius report seeing flames though there are none. Therefore the very word “flame” in connection with volcanoes is apt to cause suspicion. The only thing I can do is to repeat that I am quite certain that I saw illuminated steam frequently. The reflection of incandescent matter on steam can imitate the appearance of flames of the ordinary colour—and it frequently does—but it never can produce the effect of blue flames. Of the reddish flames, therefore, I am not so certain; but we must admit the fact of the blue flames. The only explanation, moreover, which fully agrees with the appearance of those flames is that during the explosion there escaped combustible gases which at a certain height above the crater met the oxygen necessary for taking fire. I believe that vaporized sulphur would answer all the facts better than hydrogen, the flames of which are less brilliant and less distinctly blue.
The only specimen of volcanic activity similar to that of Te Mari that I know of by personal observation is the small volcano on the southernmost of the Liparian Islands (north from Sicily) called “Volcano.” This little volcanic cone, after a long rest, resumed activity in 1888—August, I believe—emitting, at intervals, huge masses of ash-bearing steam, and sometimes large incandescent bombs, but no outflow of lava. I visited it in June of 1889, when it was making explosions similar to that of Te Mari. The explosions were, however, more frequent, there being many in one day; but they were less violent—at any rate, during my presence. The recently discharged bombs betrayed the fact that there had been magma in the depths, as their surface showed evidence of fusion; but during my presence no bombs were thrown. Besides, Volcano, in the intervals between two explosions, was perfectly quiet, and not even from the crater-rim was any smoke or steam visible at its bottom, allowance being made for some fumaroles on the outer slope of the cone. Te Mari, however, was always steaming; and after the explosion
proper it kept on steaming furiously, though with slowly decreasing power. This I observed on one occasion, and I was told that it was generally or always the case.
I had no time to make a petrographic study of Tongariro, and my few specimens are not yet analysed. I know, also, that rather basic rocks have been found in the Tongariro system. Tongariro, however, if compared with Vesuvius or Etna, probably is, as well as Volcano, far more acidic, whereas the Hawaiian volcanoes are known to be ultra-basic. It is therefore perhaps worth mentioning that the character of the activity of these volcanoes to a large extent forms a similar series, as does their chemical composition. We find, in- fact, in Hawaii enormous masses of very liquid and almost white-hot ultra-basic lava, and only a very slight amount of steam. We find the reverse in Te Mari and Volcano—very powerful explosive-like eruptions of steam and ashes, whereas the, presence of magma betrays itself only occasionally. In fact, any one who did not happen to witness one of these paroxysms at night-time might doubt the presence of red-hot magma altogether. The colour of the glare, moreover, showed a vivid red heat only; and the rather angular shape of the erupted rocks denoted a very imperfect fusion, if any. Also, the structure of the very cones—the appearance and steepness of the old lava-currents of Ngauruhoe—shows that the lava must have been viscous. Vesuvius and Etna, which, chemically, are between Hawaii on one side and Tongariro and Volcano (Lipari) on the other side, are also, in their dynamic behaviour, intermediate. Their lava-currents, which I observed frequently, as well as those of Hawaii, are less liquid, and apparently also less hot, than -those of the Hawaiian volcanoes; but the lava, besides the steam, plays a very important part in their activity. A great display of high-pressure steam and comparatively little lava, therefore, seems to be a characteristic of the more acidic volcano, whilst the opposite feature is a characteristic of the more basic one. This apparent rule, however, needs confirmation by further comparison.
In another respect Te Mari's activity is interesting; it shows that the appearance of molten, or at least incandescent, rock—viz., a shower of red-hot projectiles and a glare in the lower parts of the ascending steam—sometimes lasts a very short time only. After a personal inspection of Tarawera and Ruawahia I never doubted but that there had been molten rock, but no lava-stream proper; and after my experience with Te Mari I am, if it were possible, more certain still. It has been questioned by persons who visited Tarawera after the main explosion was over—viz., after the morning of the 10th June, 1886—if there had been any incandescent rock, and
it has even been found proper to invent a new term by denominating that destructive outburst a “hydrothermal eruption.” This term may be correct in so far that the waters of Rotomahana played a part in the eruption of Tarawera proper, or at least altered the phenomena somewhat; but, as it involves the theory that incandescent magma had no important part, if any, in the whole remarkable eruption, I cannot indorse it.
Next day I went to Ketetahi, where I saw some very fine and powerful high-pressure fumaroles, a great number of minor steam-holes, and a considerable pool of turbid hot water, the overflow of which formed a hot creek. Ketatahi is the most beautiful specimen of a fumarole I have ever seen: it is far superior to Karapiti, or any of the others in the geyser district; and it is also superior to those in the Yellowstone Park or in Italy. The whole place had, as is usual in hot-springs districts, a smell of sulphuretted hydrogen (H2S).
After this I ascended the North Crater, went to the top of Tongariro, came back again to the North Crater, and walked over to the Blue Lake, and everywhere I found the surface covered by a thin layer of very fine bluish-grey dust. From the Blue Lake I descended to the northern slope, approaching Te Mari within about 300–400 m. Te Mari had quietened down considerably in the afternoon, and its steam was almost white—i.e., without ashes—but × did not dare to go to its rim after my experiences of the previous night, as a sudden new outbreak, with enormous masses of steam, bombs, and lightning, might have proved very dangerous.
I have but little to say about Ngauruhoe. After the information I have received from old settlers and from Maori scholars (compare also what Mr. Willis says in his guide-book) I feel inclined to believe that “Auruhoe,” and not “Ngauruhoe,” is the right name. I ascended the cone on the 8th December, 1896, over the saddle between its base and the south-eastern spur of the Tongariro system—viz., from about the north-east. The upper parts have a slope of about.35°, and are mostly formed of solid lava. Viscous lava only is likely to build up a cone of that steepness. On the lower parts cinders prevail. From the slope and from the top a magnificent bird's-eye view of the Tongariro system is afforded. The crater may be considered as sufficiently known. Its rim has a gap in the north-west or north-north-west; its bottom contains one small cone of somewhat solid-looking matter, and, besides, a large and typical broad secondary cinder-cone. The latter is very excentric towards the north-west—in fact, its slope, in the already-
-mentioned gap of the main crater-rim, is confluent with the slope of the great cone of Ngauruhoe itself. This is correctly represented on the above - mentioned survey-map. In the south-west part of the crater there is a large hole, the details and bottom of which are hidden by the large amount of steam which is constantly coming out. By far the greater part of the steam had its origin in that hole, though there were many other places steaming.
Two facts betrayed a very low degree of activity—the presence of considerable masses of snow in different parts of the crater and the smell of sulphuretted hydrogen (H2S). It. is to be hoped that the expression “sulphur-fumes,” or similar words, will go entirely out of use in descriptions of volcanoes, for they convey three very different meanings—viz., pure sulphur (S), sulphuretted hydrogen H2S), or the dioxide of sulphur (also called sulphurous acid) (SO2). The latter two, moreover, exclude each other, as they readily combine to form water and sulphur. The first one—pure sulphur—is found together with the second in many fumaroles. The last one—SO2—is an indicator of a very much higher temperature and. volcanic activity. As everybody's nose easily distinguishes between the irritating, cough-producing, and choking SO2, the unpleasant smell of H2S, and the rather insignificant odour of pure sublimating sulphur, I cannot see why the ambiguous term “sulphur-fumes” plays such an important part in many reports. Even the very bad smoke of Vesuvius, which to noses not quite chemically untrained of course indicates the. prevalent presence of quite a different exhalation—viz., hydrochloric acid (HCl)—is very frequently libelled as “sulphur-smoke.” Ngauruhoe was working with the comparatively harmless H2S, while in Te Mari there seemed to be SO2; but, as I was always on the lee side, I am not sure.
As to the relation of the Tongariro system to Ngauruhoe, it is scarcely necessary to say that the former cannot be looked upon as the “somma” of Ngauruhoe. This is one of the very few mistakes I found in Hochstetter's excellent book “New Zealand,” a mistake the more excusable as Hochstetter, as he states himself, was not able to visit the volcanoes on account of the native tapu. The only formation, that perhaps, may be a “somma” of Ngauruhoe is a series of hills in the south, between the cone and Nga-puna-a-tama; but, as I saw those only from a distance—from the slope and north top of Ruapehu—I could not express a certain opinion. The reason why Tongariro cannot be styled a “somma” of Ngauruhoe is double—first, it does not surround the cone of Ngauruhoe; and, second, it bears a number of craters on the top. A “somma” is the rim of an old crater, and therefore, as its prototype, has no vents on its top.
Ruapehu I ascended on the 4th April, 1897, from the saddle between Ngauruhoe and Ruapehu. I am greatly indebted to R. T. Batley, Esq., at Moawhango, for having provided me with good horses, an excellent companion, and good advice. The most important thing is to camp out as high as possible, in order to arrive at the top early the next day, and to have plenty of time for exploring the extensive summit.
We succeeded in finding, far above the apparent line of good camping-ground, a detached patch of bush, where there were also water in some pools of a lava-gully and tussock-grass for the horses. From that place, the next day, we reached the north summit, Te Heuheu, in 3 hours 35 minutes, partly riding and partly walking. The slope was in many places free from snow, and we walked mostly on a ridge, skirting a small névé on our left (in ascending). The slope I estimate to be about 20° only.
The summit of Ruapehu is, roughly speaking, a vast, oblong, almost level plain, covered with névé—viz., hard snow—and surrounded by a number of rocky peaks, the most prominent of which are in the south, south-west, and north.
Before entering into a further description a few more general remarks may not be out of place. Ruapehu surpasses the snow-line considerably—i.e., that height above which more snow falls than can be melted. On mountains like this the excess of snow is counterbalanced, as we know, in that a part of the snow travels to lower altitudes—partly as avalanches, partly as glaciers—to be melted down below. Now, suppose a volcano surpassing the snow-line, and provided with a crater right on its top: if the crater-rim be intact, of even height all round, and no internal heat existent, the snow is bound to fill up the whole crater, and to overtop or, as it were, overflow its rim on all sides. In this case the crater must be obliterated entirely; one would find a snow-dome on its top, without any trace of a pit or hole. But as soon as we suppose the crater-rim to have one or more gaps the streams of névé, or glacier ice, can escape; and the upper parts of the inner slopes of the crater, which generally are very steep, and therefore do not hold much snow, will become visible. The drainage of frozen water, which in the former case will occur evenly all over the rim indiscriminately, in the latter case will be confined to the gaps, if they are of any extent. Instead of a complete gap, it would be also sufficient if the rim were lower on some parts than on others: the lower parts would be overflowed by the névé and the upper ones become free from snow. Anyhow, the deeper part of the crater-bottom must be covered by everlasting snow.
The crater of Ruapehu, at first sight, does not look like a crater at all. Closer and reflecting inspection, however, shows that the inner slopes of all the rocky peaks surrounding the snow-covered plain are much steeper than its outer. This and a smell of sulphuretted hydrogen, that every now and then was brought over by the cold southerly wind, reminded us of the volcanic nature of the mountain.
After having photographed the panorama from the north peak we descended its steep and partially ice-covered inner slope (it is not advisable for everybody to do this as it is better to make a detour by going round on the outer slope, saving risk and perhaps time) and crossed the snow-field to the lake. Having photographed the latter, I ascended the south-western peak, on which is a trig. (cross), and took a, panoramic view from near its top, the wind being too strong on the very top. Therefore in writing this I can help my memory by two panoramic views taken from two different points.
It seems to me to be questionable whether the top of Ruapehu is one crater only or whether it is two craters. The trouble is that the larger part of its bottom is hidden by névé; but on account of its enormously elongated shape and its rocky ridges and minor peculiarities I almost feel inclined to believe that there are two adjacent craters, a feature not altogether unknown with volcanoes, though exceptional. But this is hypothesis only. I feel, however, almost certain of the correctness of another interpretation which, I believe, has not yet been pointed out by previous visitors to the top—viz., that the famous lake (which, by-the-by, was steaming slightly and was apparently tepid) is situated not in the main crater (or, if there be two, in the southern of the two craters which cover Ruapehu's top), but in a secondary cinder-cone. I think no one who has seen a number of volcanic mountains would doubt this for a moment. The other parts of the rim, however, were almost entirely hidden by névé, the greater part of which started from the south peaks and the south-west peak, and ended at the lake abruptly in very steep ice walls. The névé hanging down the inner slopes of the south peaks look like real glaciers—i.e., ice-grey. The secondary, or inner, cinder-cone, which on the eastern side is rather high, and even forms a prominent point, visible from the north peak, must be lower or perhaps destroyed on its western parts.
If we suppose this cinder-cone to be active as an ordinary, solfatara—i.e., in quite a similar way and degree to Ngauruhoe—then, I think, we can easily understand the formation and the behaviour of the celebrated lake. Suppose hot water, steam, and sulphuretted hydrogen escaping from the bottom of the secondary cone: if Ruapehu did not mount above the snow-
line that steam would rise and betray Ruapehu as a slightly active volcano at a distance. But Ruapehu does mount above the snow-line, and the steam at first is used up for melting the snow it meets. This is the obvious origin of the lake. The cinder-cone is very excentric near the eastern rim of the southern part of the main crater. There the snow would soon be melted, and the temperature of the water might rise, if it were not for the other sides of the cone, where (more especially from the rather extensive inner slopes of the southern and south-western parts of the main crater-rim) névés or glaciers hang down, and, according to well-known laws of movement of glaciers and névés, move towards the deepest place—that is, the lake. Thus, whereas the steam has the tendency of raising the temperature of the water, the névés, of course, do the reverse. The result must depend upon the relative power of the two antagonistic forces. If steam from the depths be plentiful, and the glaciers be slow, the warm water and the steam rising from its surface may melt the snow at a certain distance, and prevent any considerable amount of frozen water from touching the lake; and then, of course, its temperature might reach boiling-point. In that case the steam from the depths would not be condensed any longer, and the lake, under such circumstances, might exhibit geyser-like phenomena. If, on the contrary, the steam from the depths be scarce, or the masses of snow travelling towards the lake be large and their rate of progress fast, the temperature would be kept down and no steam could escape, as it is readily condensed in the cold or only lukewarm water.
Ruapehu, I think, may be fully as active as Ngauruhoe (as I found it) without appearing so. There was snow in the crater of Ngauruhoe, and if Ngauruhoe were higher there would be more snow; again, if the crater were larger there would be accumulated snow; and if the steam had to deal with sufficient masses of snow it necessarily would form a lake, which it does on Ruapehu where the above conditions prevail.
It may be asked, What becomes of the water of the lake? A part, doubtlessly, evaporates; but it seems very probable that the River Wangaehu receives water from the lake by percolation. The lake is contained in a cinder-cone, situated excentrically, at the south-eastern rim of the main crater. The visible eastern surroundings of the lake are masses of dark cinders, which, of course, are easily permeable. The Wangaehu River starts from the eastern slope of Ruapehu, and its waters, as well as the waters of the lake, are turbid, and have a smell of sulphuretted hydrogen. Taking these facts into consideration, there can, I think, be but little doubt that this is the way the water takes.
It may be convenient to express my opinions concerning Ruapehu in a few short sentences:—
(1.) What is considered to be the crater of Ruapehu is possibly, in truth, two adjoining craters.
(2.) The rim of this crater (or these craters) is most perfect on the south, south-west, and north.
(3.) The snow-drainage of the crater takes place through large gaps, in the shape of névés or glaciers hanging down from the rim to the outer slopes of the mountain.
(4.) The southern portion of the main crater (or, if there be originally two, the south crater) contains a secondary cinder-cone, situated excentrically on the eastern edge.
(5.) This cinder-cone is active as a solfatara, emitting hot water, steam, and sulphuretted hydrogen.
(6.) The result of the conflict between the steam and the névé is the formation of the lake.
(7.) Its temperature depends upon the amount and temperature of steam on the one side and the amount and rate of névé travelling towards it on the other side.
(8.) The lake mostly acts as a steam-condenser, and hides, as it were, to some extent, the activity of Ruapehu.
(9.) Most likely Wangaehu draws water from the lake by percolation.
Some Practical Hints to Visitors to The Volcanoes.
As any one of the three volcanoes, in the author's opinion, exceeds in interest for ordinary tourists and in scenic beauty the whole of the hot-springs district, it is time they were made more accessible to the general public. Though none of them offer any difficulty whatever to fairly good walkers—mountain-climbing capacity proper is not required at all—it takes a good deal of trouble and, to those unacquainted with persons and circumstances, considerable expense, to get the desirable outfit on the spot, and the trouble is even greater perhaps in the case of foreigners. If good guides and outfits were obtainable at reasonable charges, and the trips were duly advertised, these marvellous volcanoes would soon not only become better known and appreciated, but would also contribute to the income of the country. I should advise everybody not to avoid a little detour if the chances of getting a proper outfit appear to become better by doing so. For the ascent, and even more so for the descent, of the mountains, especially the line of Ngauruhoe, a long strong stick is very handy. Ngauruhoe's cone in places is just steep and smooth enough to render rolling stones dangerous to those standing beneath. To traverse from east to west the cones of Tongariro on their slope is very tedious, on account of the many gullies. An ice-axe is sometimes handy on Ruapehu.
The place of our camp on Ruapehu is given by the following bearings: North peak, 146°; needle-like rock, 128°; top of Ngauruhoe, ca. 18°.
The aim is taken through dioptra from south to north. North has the figure 0, or 360; east the figure 90; south the figure 180; and west the figure 270. The given bearings indicate the reading of the north end of the needle. Therefore the reading 0 means that the object is towards the north; reading 90, towards the west; reading 180, towards the south; and reading 270, towards the east.
The needle-like rock on the right outline of the slope of the north peak is unmistakable. If you should be in doubt, there being some sharp points, take the one most to your right. I could not warrant there will always be water in the gully, but I believe there is generally.
Always take bearings from your camps before leaving them, the more so on the rolling tussock-plains or on the lower parts of the slopes. The bush-patches are difficult to identify from above, and when you return it is unpleasant to be in doubt as to where your camp and your provisions are waiting for you. This I mention out of sad experience.