always do and it is now being attacked with much vigour by some of the younger scientific workers, particularly in the Californian school: Burd, Hoagland, Kelley, Lipman, Stewart, Sharp, and others. There is also some valuable work by Gola and other Italians. The natural soil solution is not always the best for the growth of plants. It is reasonable to suppose that the most efficient method of using fertilisers would be for making up the soil solution to the optimum composition and concentration for each stage of the growth of the crop. Unfortunately, this cannot yet be done. The added fertiliser does not simply increase the concentration of the soil solution to the precise extent that might be expected; there are interactions, absorptions, and base exchanges of the kind studied first by Way, much later by van Bemmelen and by Gedroiz, and more recently by Hissink and by Wiegner. Further, the plant relationships are not constant; there is apparently-though this is not certain more response to certain nutrients at one time of its life than at another. A great advance in crop production may be expected when the soil chemists have discovered the laws governing the soil solution, when the plant physiologists can give definite expression to the plant's response to nutrients, and when someone is able to put these results together and show how to alter the soil solution so that it may produce the maximum effect on the plant at the particular time. The new soil chemistry will yet have its triumphs.

The Soil Micro-organisms: Can they be Controlled ?

It is now more than forty years since the discovery of the great importance of micro-organisms in determining soil fertility. Practical applications necessarily lag far behind; but already three have been made, each of which opens out great possibilities for the future. The long-standing problem of inoculation of leguminous crops with their appropriate organisms has already been solved in one or two of its simple cases, chiefly lucerne on new land, and the new process has helped in the remarkable extension of the lucerne crop in the United States and in Denmark. We believe at Rothamsted that the more difficult English problem is now solved also. Interesting possibilities are opened up by the observation that a preliminary crop of Bokhara clover seems to facilitate the growth of the lucerne.

The organisms effecting decomposition are now coming under control, and are being made to convert straw into farmyard manure (or a material very much like it) without the use of a single farm animal. The process was worked out at Rothamsted, and is being developed by the Adco Syndicate, who are now operating it on a large scale and are already successfully converting some thousands of tons of straw annually into good manure.

The third direction in which control of the soil organisms is being attempted is by partial sterilisation. This process is much used in the glasshouse industry in England, and it has led to considerable increases in crop yields. The older method was to use heat as the partial sterilising agent, and this still remains the most effective, but owing to its costliness: efforts have been made to replace it by chemicals. Considerable success. has been attained; we have now found a number of substances which seem promising. Some of these are by-products of coal industries; others, such as chlor- and nitro-derivatives of benzene or cresol, are producible as crude intermediates in the dye industry.

The Need for Fuller Co-operation.

Looking back over the list of problems it will be seen that they are all too complex to be completely solved by any single worker. Problems of crop production need the co-operation of agriculturists, plant physiologists, soil investigators, and statisticians. Even plant breeding necessitates the help of a physiologist who can specify just what the breeder should aim at producing. And this gives the key-note to the period of agricultural science on which we have now entered-it is becoming more and more a period of co-operation between men viewing the problem from different points of view. Good individual work will of course always continue to be done, but the future will undoubtedly see a great expansion of team work such as has already led to important results in medical research, and such as we know from our experience at Rothamsted is capable of giving admirable results in agricultural science.

The team work should not be confined to individuals working at the same institution. The world would gain greatly if co-operation such as now exists between the Imperial College Botany School and Rothamsted could be effected between other great institutions devoted to agricultural science in the various countries of the world. To take only one illustration: how much could be accomplished in the study of the very difficult alkali problem if it were possible to organise a team representing such great agricultural stations as, for instance, California and Utah, the Departments of Agriculture of India and other of the great Dominions affected, Rothamsted, Hissink's school, with power to lay down experiments anywhere and money to carry them out. And if extended co-operation of this kind should prove impossible of attainment, much could be done by fostering co-operation between the Agricultural Institutions of the Empire. There are certain great problems which are common to large parts of the Empire where the experience of one part would be of great value to the rest. The institutions in Britain, for example, have experience of problems connected with land long since settled and brought into cultivation, where men must produce 40 or more bushels per acre of wheat and 6 to 10 tons per acre of potatoes to make these crops pay, and where animal husbandry must be run on sound and economic lines. Canada has an unrivalled experience with wheat, and in the Western provinces has a magnificent chance for studying one of the most important problems of the day-the water supply to the crop. Australia, New Zealand, South Africa, East, West, and Tropical Africa, India, the West Indies-to mention only a few in the great family that forms the British Empire-all have their special lines in agricultural development; each has some achievement that can be shown with pride and in the certainty that its study will benefit others. The Empire has already its Conference of Premiers, why should it not have its conference for agricultural science and practice?

With fuller co-operation both of men and of institutions we could do much to overcome the present difficulty in regard to utilising the information we already possess. In the last thirty years an immense stock of knowledge has been obtained as to soils and crops-knowledge that ought to be of supreme value in interpreting the facts of Nature as shown in the field. It is stored in great numbers of volumes which line the shelves of our libraries, and there much of it rests undisturbed in dignified oblivion. In the main it consists of single threads followed out more or less carefully;

only rarely does some more gifted worker show something of the great pattern which the threads compose. But even the most gifted can see but little of the design; the best hope of seeing more is to induce people to work in groups of two or three, each trained in a different school and therefore looking at the problem from a different point; each seeing something hidden from the rest. Unlike art, science lends itself to this kind of team work; art is purely an individual interpretation of Nature, while science aims at a faithful description of Nature, all humanistic interpretation being eliminated. There is certainly sufficient good-will among the leaders of agricultural science to justify the hope of co-operation; there are probably in existence foundations which would furnish the financial aid.

And that leads to my last point. What is the purpose of it all? Team work, co-operation, the great expenditure of time and money now being incurred in agricultural science and experiment these are justified only if the end is worthy of the effort. The nineteenth century took the view that agricultural science was justified only in so far as it was useful. That view we now believe to be too narrow. The practical purpose is of course essential; the station must help the farmer in his daily difficulties— which again necessitates co-operation, this time between the practical grower and the scientific worker. But history has shown that institutions and investigators that tie themselves down to purely practical problems do not get very far; all experience proves that the safest way of making advances, even for purely practical purposes, is to leave the investigator unfettered. Our declared aim at Rothamsted is to discover the principles underlying the great facts of agriculture and to put the knowledge thus gained into a form in which it can be used by teachers, experts, and farmers for the upraising of country life and the improvement of the standard of farming.'

This wider purpose gives the investigator full latitude, and it justifies an investigation whether the results will be immediately useful or not-so long as they are trustworthy. For the upraising of country life necessitates a higher standard of education for the countryman; and education based on the wonderful book of Nature which lies open for all to read if they but could. How many farmers know anything about the remarkable structure of the soil they till, of its fascinating history, of the teeming population of living organisms that dwell in its dark recesses; of the wonderful wheel of life in which the plant takes up simple substances and in some mysterious way fashions them into foods for men and animals and packs them with energy drawn out of the sunlight-energy which enables us to move and work, to drive engines, motor-cars, and all the other complex agencies of modern civilisation? No one knows much of these things; but if we knew more, and could tell it as it deserves to be told, we should have a story that would make the wildest romance of human imagination seem dull by comparison and would dispel for ever the illusion that the country is a dull place to live in. Agricultural science must be judged not only by its material achievements, but also by its success in revealing to the countryman something of the wonder and the mystery of the great open spaces in which he dwells.

REPORTS ON THE STATE OF SCIENCE,

ETC.

Seismological Investigations. - Twenty-ninth Report of Committee (Professor H. H. TURNER, Chairman; Mr. J. J. SHAW, Secretary; Mr. C. VERNON BOYS, Dr. J. E. CROMBIE, Dr. C. DAVISON, Sir F. W. DYSON, Sir R. T. GLAZEBROOK, Dr. HAROLD JEFFREYS, Professor H. LAMB, Sir J. LARMOR, Dr. A. CRICHTON MITCHELL, Professors A. E. H. LOVE, H. M. MACDONALD, and H. C. PLUMMER, Mr. W. E. PLUMMER, Professor R. A. SAMPSON, Sir A. SCHUSTER, Sir NAPIER SHAW, and Dr. G. T. WALKER). [Drawn up by the Chairman except where otherwise mentioned.]

General.

THERE is no modification to report in the general situation at Oxford. The tenant of the house purchased by Dr. Crombie's benefaction shows no disposition to move; but the work has been carried on in the 'Students' Observatory' without serious difficulty.

The salary for Mr. J. S. Hughes, provided for the first year entirely by the generosity of Dr. Crombie, has for the second year been provided half by Dr. Crombie and half by the Board of Scientific and Industrial Research. Mr. Hughes has taken over the work of determining epicentres and times, under the general supervision of Professor Turner, and by this welcome addition to our resources arrears are being steadily reduced, as mentioned below.

International.

Seismology has sustained further severe losses by the deaths of Dr. Otto Klotz of Ottawa and Professor Omori of Tokyo. Our deep sympathies are extended to Japan, not only for this personal loss, but on account of the terrible calamity which befell Tokyo and Yokohama in the devastating earthquake of September 1.

There is to be a meeting of the International Union for Geodesy and Geophysics in Madrid in October next. Professor H. H. Turner and Mr. J. J. Shaw have been in nominated by our National Committee as delegates for Seismology.

Instrumental.

Nothing has yet been heard of the seismograph taken to Christmas Island by the Eclipse observers in 1922. Writing under date June 4, Mr. H. S. Jones, now H.M. Astronomer at the Cape, promises to write again to Christmas Island on the subject.

Mr. J. J. Shaw has despatched two of his seismographs to Entebbe in Uganda, and one to Fordham University, New York. These were independently purchased, but are mentioned to show the expanding distribution of machines of the type approved by the Committee.

Another instrument has been prepared by him for exhibition at Wembley, whither some maps showing the distribution of epicentres and of observing stations, and a set of the publications, are also being sent.

The performance of the Milne-Shaw seismograph has, moreover, been tested by Professor Rothé on the experimental table at Strasbourg with very satisfactory results. The curve representing the motion of the table is almost identical with that shown by the seismograph.

[The remainder of this section is due to Mr. Shaw.]

The movements of the table are produced by an electrically driven cam, the amplitude and periodicity of which can be changed at will. Its motion is recorded mechanically on smoked paper. The seismograph is placed upon the table, but records photographically. Both curves are timed by the same electric circuit. The apparatus was tested with both simple and complex periods and in each case faithful records were obtained.

Fig. 1 illustrates curves where the periods of the table and pendulum were alike (a condition when distortion due to synchronism is most likely to develop). Curve A shows a table movement of 0·13 mm. magnified 109 times. B is the corresponding seismogram, in which, by the Galitzin formulas, the magnification should be 187.

Measurement of the curve shows magnifications ranging between 181 and 187, illus. trating not only the fidelity of the seismogram but also the close agreement between present practice and the formula in use.

While referring to instrumental points of this kind, it is interesting to observe how two machines standardised to similar constants and fully damped do produce similar