432 Proceedings of the geological society. [June 28,
fact that improved drainage had been found to exert a marked influence
upon the average number of deaths by consumption in
certain districts. The chief result arrived at by an examination of
fifty-eight registration districts in Kent and Sussex was, that "wetness
of the soil is a great cause of consumption;" and this depends
not only upon the perviousness or imperviousness of the soils, but
upon their position as regards elevation and slope.
Discussion.
Prof. Brayley mentioned a paper by Mr. Mackinnon on the same subject, communicated to the Royal Society some years ago.
Dr. Duncan commented on the value of such inquiries, and mentioned that in Devonshire families living in the valleys were peculiarly liable to consumption, while those living on the hills were free from the disease.
8. On the Volcanic Phenomena of Hawaii. By the Rev. C. G. Williamson. Communicated by Sir R. I. Murchison, Bart., F.R.S., V.P.G.S.
[Abstract.]
The author describes the general configuration of the island of Hawaii, and refers especially to the arrangement of the three great volcanic cones which form its highest points. Mount Kea (13,953 feet) and Hualalai (10,000 feet) have been quiescent for many years*; but Mount Loa (13,760 feet) is still in a state of constant activity. In the extreme north of the island is the Kohala ridge of cones (about 5000 feet), which appear to have been long extinct. The bases of the three great volcanoes, which stand nearly in an equilateral triangle, are united by an elevated plateau forming the centre of the island, sparingly clothed with vegetation, and having many conical hills, from which lava appears to have flowed, scattered over it. In descending from the high grounds there is a belt of woods, in which the vegetation gradually becomes more tropical in its character; and this continues to be the case on the lowlands to the coast. The fertile districts are all within the limit of rains; and here the older lavas, of which the surface consists, are more or less decomposed. The author describes the general characters of the surface, and states that the greatest alteration of the surface has taken place in the northern parts of the island; hence he concludes that the centre of volcanic energy in the island has gradually been moving southward, the outpourings from the Kohala hills and Mount Kea, which have undergone most alteration, being, in his opinion, the oldest, and the southernmost volcano, that of Mount Loa (including Kilauea), being the only one now in activity.
The author notices the history of the activity of Mount Loa since the year 1832, when its first recorded eruption took place. A
- The last eruption of Hualalai took place in 1801.
