698 



SCIENCE 



[N. S. Vol. XXX. No. 774 



ways even when following the same code. 

 This difference may be due to the fact that 

 one author has more abundant material upon 

 ■which to base his conclusion, or it may be due 

 to a difference of opinion as to the relation of 

 the organisms, or in the interpretation of the 

 work of others. Differences in the applica- 

 tion of names due to these causes are not the 

 result of imperfections in the code followed, 

 and no code can eliminate such changes. In 

 fact it would be very unwise to attempt such 

 elimination. Students must not be handi- 

 capped in serious study. On the other hand, 

 it is well to discourage the study of nomen- 

 clature as apart from the study of organisms. 

 I believe it is impossible for any person or any 

 committee, to prepare a list of organisms 

 which shall be permanent ; partly because such 

 person, or committee, may not be sufficiently 

 familiar with the organisms, and partly be- 

 cause the knowledge concerning these organ- 

 isms is ever increasing. The value of a code 

 of nomenclature should be judged by its use- 

 fulness in determining the application of 

 names, rather than by the changes that may 

 result. A. S. Hitchcock, 



Systematic Agrostologist 

 Department of Agriculture, 

 Washington, D. C. 



THE MAGNETIC STORM OF SEPTEMBER 25, 1909 



An exceedingly severe magnetic storm was 

 recorded at the Cheltenham Magnetic Observa- 

 tory on September 25, 1909, the first indica- 

 tions appearing as a slight disturbance of the 

 magnets at 3:27 a.m., 75th meridian time. 



The period of greatest disturbance began at 

 6:39 A.M. and lasted until about 4 p.m., and 

 during most of this interval the movements of 

 the recording magnets were so sudden and of 

 so large amplitude that the spots of light 

 failed to produce any impression on the pho- 

 tographic paper, except in the case of declina- 

 tion, where a partial record was secured. 



From 6:39 to 8:17 a.m. the changes in the 

 earth's magnetism were so great that the mag- 

 nets were deflected far out of their normal 

 positions and the spots of light passed beyond 

 the limits of the photographic paper. During 

 this interval the magnets which furnish a 



record of the changes in vertical intensity 

 were upset by the variations in the earth's 

 magnetism. These magnets are balanced on 

 a knife-edge or a pair of fine points and are 

 extremely sensitive. 



As there was no observer on duty until 

 8 :00 a.m. no estimate can be made of the 

 changes during the interval of greatest dis- 

 turbance. The actual ranges of the magnetic 

 elements during this storm are therefore un- 

 known. 



Two complete magnetographs are in opera- 

 tion at this observatory and are arranged to 

 give continuous photographic records. Each 

 consists of three instruments arranged to give 

 record of the variations in the three elements, 

 declination, horizontal intensity and vertical 

 intensity, respectively. One of the magneto- 

 graphs, the " Adie," is also fitted with tele- 

 scopes and scales, so that the position of each 

 magnet may be observed and the actual value 

 of the element determined at any instant. 

 These scales cover a range in the position of 

 the magnet about two and one half times as 

 great as that covered by the paper. 



DECLINATION (West) 



75th met. time Value 



h m ° ' Remarks 



6 39 A.M. 6 29 Oflf paper. 



8 00 6 46 Eye reading. 



8 05 8 22 Eye-reading maximum. 



8 19 3 25 Minimum. 



1 18 P.M. 4 44 



1 52 6 29 



1 58 6 54 



2 38 6 40 



5 36 Normal value. 



HORIZONTAL INTENSITY 



75th mer. time Value 



h m c.g.s. Remarks 



8 05 A.M. .17900 Estimated. 



9 22 .19680 



10 41 .19187 Eye-reading minimum. 



10 52 .19336 



1 19 P.M. .20343 Eye-reading maximum. 



1 58 .19397 



2 38 .19351 f Change of 901 gammas in 

 2 43 .20252 | 5 minutes. 



2 46 .19481 



3 16 .20301 



.19878 Normal value. 



