72>^ 



NATURE 



[August 4, 192 1 



The Wielandt machine is similar in principle to the i 



Baumann, but lighter in construction, largely owing '. 



to the adoption in it of a different spreading ^ 

 mechanism. The machine can be driven by a 25-h.p. 



electromotor, and its total cost, including motor and i 



cables, was loooZ. four or five years ago, but is now i 



much higher. During- the war it was found at Elisa- i 



bethfehn, in Oldenburg, that one of these machines, 1 



attended by one man and three or four youths, had j 



an output in the season of 7000 tons of air-dry | 



turf. I 



If the statements made abroad with regard to the | 



efficiency of automatic machines are correct, four of | 



these machines, attended by sixteen men in all, can | 



dredge, form into sods, and spread in a day enough | 



peat to yield, when air-dry, about 250 tons of turf. 

 The same output of peat, cut and spread, by the 

 method ordinarily practised in Ireland requires about 

 160 men. It is therefore a matter of great importance 

 for the winning of peat on a large scale in Ireland 

 that these claims should be subjected to a prolonged 

 test under the conditions obtaining here. In con- 

 clusion the writer must again express his regret that 

 the recommendations of the Peat Inquiry Committee 

 were ultimately set aside for reasons which are in 

 part due to misinterpretation of the Peat Committee's 

 report, and in part to statements which were made by 

 the Agricultural Sub-Committee, and are in sharp dis- 

 agreement with the actual facts, in regard to the 

 extent and the purchase price of Irish bogs. 



Geophysical Problems. 



A SURVEY of research problems in geophysics has 

 recently been published by the American Geo- 

 physical Union, a body which acts as the Committee 

 on Geophysics of the National Research Council, and 

 as the United States National Committee of the 

 International Geodetic and Geophysical Union. The 

 survey consists of a series of seven essays by the 

 chairmen of the several sections of the union, deal- 

 ing respectively with geodesy, seismology, meteorology, 

 terrestrial magnetism and electricity, physical oceano- 

 graphy, volcanology, and geological physics and 

 chemistry. It is interesting to observe that the two 

 latter subjects, so little studied in this country, are 

 in America found sufficiently important to occupy 

 separate sections of the union. 



Advance in nearly all these branches of geophysics 

 seems to depend on much the same method of attack, 

 in\f&lving on the one hand an enormous amount of 

 organised, co-ordinated labour of observation and 

 measurement, and on the other individual theoretical 

 study, necessarily of a freelance character, by a 

 comparatively few people with scientific training, in- 

 sight, and wide knowledge, at research institutes or 

 universities. The first half of the task is being 

 executed with increasing skill and success by the 

 national scientific organisations of the leading 

 countries, but the complementary half lags behind. 

 Dr. C. F. Marvin, for instance, after describing the 

 present achievements and future tasks of meteor- 

 ological organisations, concludes that "seemingly the 

 greatest need in meteorology is that of a master mind 

 to direct itself comprehendingly and intensively to the 

 great problems which the science still presents." The 

 recency of the beginning made by meteorologists in 

 the study of the upper air, now recognised to bt 

 fundamental for the upbuilding of a dynamical science 

 of meteorology, suggests that perhaps also in other 

 geophysical sciences progress may be obstructed by 

 failure to perceive vitally important directions which 

 observation and research must take. 



The outstanding task of geodesy at the present time 

 is described by Prof. Bowie as being that of co- 

 ordinating the geodetic triangulations of the various 

 countries by reducing them to a single datum, 

 defined as the adopted latitude and longitude of some 

 one station, the azimuth of a line radiating from 

 that station, and the dimensions of the reference 

 spheroid on which the triangulation is computed. This 

 involves a herculean work of re-computation and re- 

 adjustment of the triangulation networks, especially 

 in Europe ; in America much progress in this direction 

 has already been made. Gravity surveys must be ex- 

 tended over the land surfaces, and a satisfactory 

 method of observation evolved for the ocean areas of 

 NO. 2701, VOL. 107] 



the globe ; this will afford information as to the varia- 

 tions of density in the earth's crust, enable the theory 

 of isostasy to be further developed, and thereby lead 

 to ever closer approximations to the figure of the 

 earth. 



In seismology the most important world-wide 

 problem is the accurate determination of the time 

 taken by earthquake waves to travel from their origin 

 to other points on the earth's surface; this information 

 is necessary in order that the origin of earthquakes 

 arising in inaccessible (land or oceanic) regions may 

 be determined, and that the velocity and path of the 

 waves within the earth may be deduced, thus throw- 

 ing light on the earth's internal constitution. Prof. 

 Reid expresses the opinion ^hat the most useful means 

 to this end lies in the improvement of the equipment 

 of existing seismological observatories rather than 

 in multiplication of the present number. The de- 

 sirability also of methodical studies of limited areas 

 where small shocks are frequent and strong ones 

 occasional is also mentioned, with the view of deter- 

 mining the sequence of events leading up to the 

 rupture producing a strong shock, and possibly of 

 forecasting the region and time of such occurrences. 



Dr. Bauer's article on terrestrial magnetism con- 

 tains some interesting remarks on the progress of the 

 analysis of the earth's magnetic field which is now 

 being made in the department of the Carnegie Insti- 

 tution which he controls. It has been concluded that 

 for many purposes the theoretical formula proceeding 

 in series of spherical harmonics may be restricted 

 to the few most important terms, leaving the residual 

 field, representing continental and more local irregulari- 

 ties, for special study and treatment in accordance 

 with their extent and character. Reference is also 

 made to the important problems afforded by the mag- 

 netic variations, both those connected with aurorae 

 and earth-currents, and the rarer ones occurring at 

 times of solar eclipse. The baffling fundamental 

 problems of the origin of the earth's main magnetic 

 field and the cause of its secular variation are also 

 touched upon. 



Prof. Littlehales points out the influence which 

 the ocean, being so large an expanse of the substance 

 having the highest known capacity for heat, must 

 exercise as a factor governing the distribution of 

 terrestrial temperature, and the consequent importance 

 of oceanography to geophysics in general. A 

 resumd is given of the efforts so far made, by voyages 

 of exploration and by investigations in marine labora- 

 tories, towards the study of the oceans in their many 

 aspects ; the system according to which progress is 

 now being sought is the study, in detail, of definite 

 oceanic stations periodically revisited every three 



