May 5, 1910] 



NATURE 



277 



1 nonet. Runge's law is applicable to 5770 ; the type of 

 nonet is such that the lines form aliquot parts of 

 fn.H/4x, and the difference in the number of vibra- 



.luiis of these lines can be represented by 



, a .8 ,0 I 10 



' -8 8 8 ' 8 



g 

 Considered as a triplet, which corresponds to lines o, +ca, 



Gmelin found that e/m=:202 X 10^ ; v. Baeyer and Gehrcke 

 abtained 2-06 X 10', which is also the number I have arrived 

 at from the same standpoint. Considered as a nonet, how- 



2ver. we have to multiplv the above number by -, so that 



corrected result turns out to be : — 



' imelin 

 •jehrcke and 

 Nagaoka 



v. Baever 



i-8ox 10' 

 1-83 X 10' 

 1-83 X 10' 



This is in close agreement with the same constant obtained 

 from measurements on the nonet of the mercury line 5461, 

 for which e/m= i-8oX 10'. 



The above examination of the line 5770 shows how the 

 ' "— ?nt t>pes of a class of nonets are derived from normal 

 ts. 



irting from the normal triplet A, we get nonets of 

 [types B, C, and D by doubling the intervals of component 



Fig. I. 



lines of each group, as shown in Fig. i. Considered as 

 nii-iuot parts of a, they are represented by 



B. o, +-, +-a, +2^, ± — a. 



' -g' -8 8 8 



C. o, ±?, +I1, ±5^, ±tx. 



4 4 4 4 



D. O, +-, ±-a, ±3a, +4^, 



2 2 2 2 



w^ith direction of electric force as shown in the figure, p 

 indicating that it is parallel, and 5 at right angles, to the 

 direction of the field. B is represented by the line 5770, 

 C by the neon lines 6678 and 6305, and D by the mercury 

 line 5461. Probably there is also a type 



^ .a ,16 .17 .18 

 O, + — . + — a, +-^a, + — a, 

 -16 -16 16 -16 ' 



intermediate between A and B. Of the different lines 

 which I have examined, the copper line 5105 seems to 

 belong to this type, but as it requires high resolving power 

 I have not been able to clear up this point. It appears 

 to me quite probable that triplets, which show broadening 

 of lines and no asymmetry in high fields, and give values 

 of efm greater than 1-87x10', l)elong to some of the inter- 

 mediate types. H. Nagaoka. 

 Physical Institute, University of Tokyo, March 29. 



The Fertilising Influence of Sunlight. 



Is Nature of February 17 is a communication from Mr. 

 and Mrs. Howard pointing out that the probable explana- 

 tion of the advantage of leaving land rough ploughed 

 during the hot weather in India is that the biological 

 changes which occurred under the conditions of Messrs. 

 Russell and Hutchinson's experiments occur here also. 



NO. 2 II 4, VOL. 83] 



The following temperature record, which is one of the 

 highest I have, will be of interest in this relation : — 



Date, May 28, 1906. 



Maximum shade tcmpeiatuie 



Maximum temperature of ioil 3 in. deep 

 >f >» It o ,, 



»f f> »» 9 »> 



,. » >> 12 „ 



»> >> »> 24 ,, 



Other records of soil temperature in Behar are published 

 in " An Account of the Research Work in Indigo at 

 Dalsing Serai, 1903—4," by Bloxam, Leake and Finlow 

 (Appendix ii.). Temperatures approximating to 50° C. at 

 I inch from the surface were recorded. 



The hoi-weather temperature here (Behar) is not so high 

 as in some other parts. Jacobabad " enjoys " one which runs 

 up to 127° F. on occasions, and the whole of the western 

 part of the Punjab (an area equal to about twice that of 

 the British Isles) is liable to maximum air temperatures 

 of iio°-ii5° F. (43°-46° C), so that the surface soil in 

 that part may be assumed to attain an average temperature 

 some 10° F. (5° C.) higher than here at Pusa ; but it is 

 certain that, however uncomfortably hot India is, its soils 

 never attain a temperature anything approaching 100° C. 



Dr. Russell mentions (Nature, March 3) that biological 

 changes at temperatures below 100° C. are being studied, 

 so that we shall doubtless learn shortly in how far they 

 assimilate under these conditions to the efifect at 100° C. 

 In any case^ it must not be forgotten that there cannot 

 be much difference in temperature between roughly 

 ploughed land and unploughed land which has carried a 

 cold-weather crop ; in both the amount of moisture in the 

 first 6 inches will be nominal, and the thermal capacity 

 of each must be much about the same. The roughly 

 ploughed soil will include more air, and I should expect 

 the rise of temperature at 6 inches to be rather greater 

 in unploughed land. Hence if this agricultural practice is 

 found to be accompanied by important biological changes, 

 this must be due to some cause other than mere tempera- 

 ture. 



Regarding the effect of sunlight, this can only affect 

 the outside surface ; in unploughed land this is better 

 defined than in broken-up land, and during the ploughing 

 operation more soil is exposed (temporarily) to the sun 

 than in the former case, but the ploughing here referred 

 to is commonly one ploughing, not a " multiple stirring " 

 such as occurs in the preparation of the seed bed. 



Finally, it is perhaps unnecessary- to mention that this 

 rough ploughing results in other advantages than those 

 mentioned. One is that the soil absorbs more of the first 

 monsoon rain than unploughed land, and can be prepared 

 for monsoon crops much more quickly. 



Pusa, April 13. j. W.alter Leather. 



Observations of Halley's Coniet. 



I s.\w Halley's comet through field-glasses on Sunday 

 morning, April 24, at 3.40. It was then about 10° above 

 the horizon, 20° to the left of Venus, and slightly under it. 

 It was very distinct from 4.0 to 4.20. At its best. 4.15, I 

 could just distinguish the head by the naked eye, but only 

 for a minute. 



The tail appeared broad and short, only about twice the 

 moon's apparent diameter in length, with its axis at 40° to 

 the horizon. The tail began to grow indistinct at 4.30, but 

 the head was visible to 4.45. 



The sky was not ideal, Pegasus not distinct, Cassiopeia 

 only partially seen, but Venus was very distinct and bright. 



I saw the comet again jesterday — Monday, April 25 — 

 from 4.0 to 4.15. The sky was not at all clear. The 

 comet was in a line with Venus, and still about 20° to 

 the left. I could not s^'e it with the naked eye. 



This morning, April 26, comet was clearly seen from 

 3.45 to 4.30. The tail appeared longer and more elegant 

 in appearance. It was perhaps 5° above Venus, and less 

 than 20° to the left. The head was easily seen at intervals 

 by the naked eye, but the tail showed only a trace, and 

 that only once. 



The measurements are only by the eye, but are, I think» 

 fairly correct. ' c. Le.*ch. 



Malta, April 26. 



