SCIENCE OF THE DAY.

New Zealand Herald, Volume LXVII, Issue 20650, 23 August 1930, Page 5 (Supplement)

SCIENCE OF THE DAY.

IRRIGATION AND THE SOIL.

The recently issued Bulletin of tho New Zealand Geological Survey, " Tho Soils of tho Irrigation Areas in Central Otago," by Mr. H. T. Ferrar, is tho first issued by the Survey that deals with soils. It most p.ttractively advertises this comparatively recent addition to the activities of this branch of the Department of Scientific and Industrial Research.

The Bulletin publishes an introductory statement dealing with facts of general interest about'tho area of Central Otago, with which it is concerned. It sketches in lucid fashion geological events that have led up to the . development of its extraordinary intermontane plains, which are the areas most likely to benefit from irrigation projects, whilst it also deals briefly with some of tho physiographic consequonces of the severe glaciation that affected the western parts of the district in the not-distant past. Professor J. A. Bartrum, of tho Auckland University College, writes'" The main value of the Bulletin lies in its presentation of sixteen admirable, beautifully coloured soil maps, which are also of interest to the geographer in demonstrating convincingly the present concentration of population in tho intermontane lowlands.. They cannot hope to portray every variation of soil type, but their detail is, nevertheless, so considerable, that they furnish a most valuable insight into the soil problems of Central Otago. Tho characters of the soils there, have very close dependence upon tho parent rock from which they have been derived, and upon mode of origin, but, from the point of view of their utilisation, there must bo coupled witji these factors their need avid adaptation for irrigation, so that Mr. Ferrar has embodied all these important considerations in his classification of soil types. As a result, tho maps, which show the distribution of such types, have an immediate practical utility. " In his final chapter, the author discusses many of the problems of irrigation, especially with regard to tho supply and wastage of the necessary water, and possible development of unfavourable alkaline conditions of the soil irrigated. He doubts if sufficient water is available from high-level sources, and points out the serious economic problem raised, if it has to be pumped from the deeply entrenched major streams.

" The soils of most New Zealand areas are youthful in character and show, therefore, a close relation to parent rock. For this reason agro-geological surveys, such as are now T)eing undertaken hy the New Zealand Geological Survey, are of vital importance in grouping our soils into classes and provinces, each with its own distinctive features and needs, and in preparing the way for intensive work by the soil chemist and biologist." THE POWER OF PEARLS. It is claimed that genuine pearls can now be distinguished from fasle ones with scientific accuracy. An English expert, H. C. Hopkins, has found that the concentric layers forming a true pearl may bo identified by the particular way in which they reflect and transmit light. He has devised a special instrument which uses light from mercury vapour to detect this power of true pearls. Hence the fear that true pearls would lose their value because of the Japanese stimulated variety is not so terrifying to dealers. The Japanese pearl, produced in the past by inserting a bit of mother of pearl within the oyster's shell as a nucleus to stimulate pearl secretion, has held its own with the true gem. The Chinese were the first to discover that pearls grow inside the oyster about some irritating foreign body. They tried to create a substitute for the natural process by planting bits of mud or wood within the shell. SCIENCE AND THE BIBLE. Half a century ago, when the conflict between science and theology first attracted wide notice, it seemed as if biological discovery had destroyed the value of the Bible as evidence. Now, says a recent writer, the pendulum has swung the other way. Almost every year fresh material is brought to light, confirming that oven the most legondary facts of the Old Testament may have an historical basis, But the subjoct has many difficulties. Special caution is demanded, together with a tolerant and common-sense attitude, if the truth is to bo discovered. Work in Palestine since the war has thrown light particularly upon the period of Joshua and Judges. There is now no reason to doubt that the traditions embodied in the old documentary sources of both Books were founded on fact. SEEDS AND RADIO. Selection of seeds by radio is pronounced thoroughly successful by Maurice Larvaron, professor of agriculture at the Rennes Farm School, France. Thorough tests with potatoes and wheat, he says prove that the quality of seed can be determined by gauging waves emitted by the seeds. The emanations affect a delicate pendulum in an apparatus devised by Dr. Jules Regnault.