264. MR. T. F. CHEESEMAN ON 
water flow down most of these; in fact the centre of the island is remarkably well 
watered. But, except after heavy rains, most of the streams disappear after reaching the 
belt of sandy and porous soil near the shore. The only stream which is absolutely 
permanent is one which has its source on the southern side of Tekou, and falls into the 
sea at Ngatangiia Harbour. 
The geological structure of the island is purely volcanic. The sections exposed in the 
gorges, or on the precipitous sides of the mountains, show numerous lava-flows 
interbedded with conglomerates and ash-beds. No sign of a crater can be made out ; 
but this is not surprising, for evidently the island has suffered so severely from 
denudation that only the skeleton of its former structure remains. 
The climate is, on the whole, equable, the temperature rarely rising above 90° Fahr., or 
falling below 60°, although I believe that readings as low as 50° have been taken. The 
hottest time of the year is the period from November to April, which is also the rainy 
season. From May to October are the dry months, with usually a lower temperature, 
especially at night. But there is much variation, and heavy rains may occur at any 
time of the year. The total annual rainfall is about 90 inches, the monthly total 
ranging from 1$ to 16 inches. Heavy falls of 2 or 3 inches or more in a few hours are 
not uncommon, and are usually accompanied with much thunder and lightning. 
Hurricanes are rare, and no serious one had occurred for many years previous to my 
visit. Fever is practically unknown; and, generally speaking, the climate must be 
considered remarkably healthy for a tropical locality. 
Coming now to the vegetation, it can be roundly said that the whole island is covered 
with forest. Here and there a bare rocky face shows out on the sides of the mountains, 
and the slopes of a few hills are free from trees, but the total area of open land is quite 
insignificant. Even the eultivations of the natives—their orange-groves and coffee- 
plantations, their Banana- and Taro-patches—are either part and parcel of the forest or 
are sheltered and almost overshadowed by it. And with the exception of Ferns, which 
are everywhere plentiful, there are few low-growing herbaceous plants. Even most of 
the weeds are tall and robust, with woody stems reaching quite over one's head. And 
the forest has a recuperative power which, though common enough in a warm and 
moist tropical climate, is at first positively amazing to a stranger coming from cooler 
lands. No sooner has a clearing been abandoned than young trees everywhere spring 
up. In twelve months they have formed a jungle; in two years they are fifteen or 
twenty feet in height, and every vestige of former cultivation is gone. Speaking of the 
vegetation in general terms, there can be no doubt that the first impression conveyed to 
the mind is that of extreme luxuriance of growth and of richness and diversity of foliage. 
Butjthere is no extraordinary display of floral beauty, and the trees, although many of 
them are handsome enough, are not remarkable either for size or symmetry of shape. 
Comparing the vegetation with that of New Zealand, with which a residence of many 
pus has made me familiar, I can say that there is nothing in Rarotonga, nor probably 
In the whole of Polynesia, that can compare with a well-srown Kauri Pine (Agathis 
australis) or Totara (Podocarpus Totara), and no Raroton 
GUN illi gan plant can offer a more 
& ^ t mass of colour than the Pohutukawa ( Metrosideros tomentosa). It is, as hinted 
