2.^0 



NA rURE 



[July 4, 1901 



possible to grow two cereal crops each season — wheat 

 from November to July and maize from July to October. 

 The results show that the a\erage yield of wheat is a 

 good deal lower than in England, for instance ; but the 

 two crops taken together furnish an amount of grain in 

 excess of the yields of the single crops obtained in 

 England, Germany and the north of France. The charac- 

 ter of the climate of .Suessola is further illustrated by the 

 fact that Rabi wheat from Oudh tends to give increased 

 crops when grown in this district. English wheat, on 

 the other hand, was found to deteriorate. 



.A.S regards the effect of the different manures on the 

 wheat crop, horse-dung with sulphate of ammonia, ap- 

 plied in the spring, gave the highest yield, both of grain 

 and straw. Sulphate of ammonia alone, applied in the 

 spring, gave a higher yield of grain, but less straw than 

 when applied partly in the autumn and partly in the 

 spring ; this result is attributed to the excessive rainfall 

 during the winter months. With nitrate of soda there 

 was a much lower yield of grain and rather less straw 

 than with sulphate of ammonia. In accordance with 

 what has been observed at Rothamsted and at Woburn, 

 Giglioli obtained a greater weight per bushel under the 

 influence of sulphate of ammonia than with nitrate of 

 soda. Both these manures proved to be very effective 

 when applied in conjunction with horse-dung. In this 

 connection it may be mentioned that, quite recently, 

 Hiltner has found that when humous sandy soil and 

 heavy soil were inoculated with certain denitrifying 

 organisms an increased production of oats was obtained. 

 These results lend support to the \iew, now very generally 

 accepted, that, in practice, the danger of any consider- 

 able loss of nitrogen under the influence of denitrifying 

 organisms has been a good deal over-estimated. 



Basic slag alone very considerably increased the yield 

 of wheat grain ; a still further increase in grain and also 

 in straw was obtained when horse manure, or a mi.xture 

 of sulphate of ammonia, nitrate of soda and potassium 

 chloride were applied in addition to basic slag. E.\- 

 clusively nitrogenous manures in addition to basic slag 

 yielded about the same amount of grain, but more straw, 

 than basic slag alone. Mineral superphosphate gave 

 less satisfactory results than basic slag. Leucite, which 

 occurs in large quantities in Italy, especially Roccamon- 

 fina, increased the yield of wheat when applied along 

 with nitrate of soda ; in conjunction with basic slag and 

 nitrogenous manures, it produced about the same effect 

 as potassium chloride under the same conditions. 



Some interesting results are recorded on the effect of 

 manganese dioxide, applied with various manures. 

 These experiments, which have now been continued for 

 three years, tend to show, in the majority of cases, that 

 manganese dioxide in some way benefits the wheat crop. 

 Further experiments on the subject, in which other 

 crops, such as mangels, might be included, are desirable. 



Electro-culture experiments w^ith wheat manured with 

 horse-dung showed a distinct gain both in grain and in 

 straw when atmospheric electricity was employed, the 

 increase in grain being relatively the greater. A'oltaic 

 electricity produced a still more marked effect, and 

 increased the yield both of grain and straw by about 

 to per cent. 



It has not been possible within the limits of this short 

 NO. 1653, VOL. 64] 



notice to give much more than a general indication of the 

 lines of Prof Giglioli's carefully conducted series of 

 experiments, which, as time goes on, cannot fail to gain in 

 interest and value. The present Report is well arranged 

 for reference, and contains excellent bibliographies of 

 some of the subjects investigated. The second Report, 

 dealing with the results of the maize experiments, will, it 

 is hoped, be ready before very long. N. H. J. M. 



EARTH CURRENT MEASUREMENTS. 

 Die Erds/romc im Dciiischen Reichstelegraphetigebiet 

 unci ihr zusammenlians; init den Erdmagneiischen 

 Erschchitiiigcii. By Dr. B. Weinstein. Pp. vi-t-yS, and 

 Atlas to ditto. (Brunswick : Friedrich Vieweg and 

 Son, 1900.) Price, Mk. 4. 



OF late years, when the interests of the electric rail- 

 way and tramway have clashed with those of the 

 observatories in which magnetic and earth current 

 measurements are made, it has frequently been urged 

 by the opponents of the observatories that they continue 

 year after year accumulating data of which no use is ever 

 made. Unfortunately, in most cases, owing, no doubt, to 

 the very inadequate staff and multitudinous duties they 

 have to perform, there is a certain amount of truth in this 

 contention. It must, however, not be forgotten that the 

 material is always available and can be worked up at any 

 future date, while if the observations are interrupted, for 

 however short a time, no amount of money or trouble ex- 

 pended at a subsequent time can replace the missing 

 measurements. In this connection it is, therefore, with 

 considerable pleasure that we welcome this pamphlet of 

 nearly eighty pages, together with a quarto volume of 

 curves, which give an account of the measurements made 

 of the earth current curves obtained in two lines, one 

 running between Berlin and Dresden, and the other 

 between Berlin and Thorn during the epoch 1884-1888. 



The author considers, in the first place, the manner in 

 which the earth currents change, and in the second place 

 to what extent these changes are connected with simul- 

 taneous changes in the terrestrial magnetic field. 



In order to investigate the periodic changes in the 

 earth currents, the ordinates of the photographic curves 

 were measured for every hour and the means were used 

 to calculate the coefficient of a Fourier expansion. The 

 agreement between the values of the coefficients derived 

 from the means for the various years is quite surprising 

 considering the irregularity which one associates with all 

 earth current phenomena. 



The two lines being very nearly at right angles, and 

 making the supposition that the current measured in the 

 line is proportional to the current which traverses the 

 earth, the author is able to calculate for each hour of the 

 day the azimuth in which the current is flowing through 

 the earth's crust. He compares the azimuth of this 

 resultant current with the azimuth of the trace of the 

 vertical plane passing through the sun. The results of 

 these measurements, as well as a consideration of the 

 way in which the earth currents change in magnitude 

 and direction for the various months of the year, are all 

 most clearly shown by means of vector diagrams. Vector 

 diagrams are also given to show the changes in the 

 earth's magnetic field for various stations, and a com- 



