Mat 19, 1922] 



SCIENCE 



545 



tinguished from the others. An argument against 

 the Island Universe theory was drawn from a 

 series of photographs of a spiral nebula, taken 

 over a space of five years and showing marked 

 changes in the nebula from year to year. It was 

 argued that changes in a whole universe so 

 marked as to be plainly visible at such enormous 

 distances, and occurring within the time space 

 of five years, would be very extraordinary. A 

 similar argument was found in the prominence of 

 the central star in spirals. 



A recording micrometer: A. E. Douglass. A 

 description and demonstration of a portable 

 micrometer, which records its readings directly 

 to scale on cross section paper. This instrument 

 was developed in connection with researches on 

 the rings of trees and their relation to climatic 

 cycles, but can be used equally in telescopes. 



The spectrum of the night sky and of the 

 aurora of May 14, 1921 : V. M. Sliphek. In ob- 

 servations made by the author, the auroral line 

 is easily determined in the spectrum of the night 

 sky. It shows up at Flagstaff even on cloudy 

 nights. Careful observations made there deter- 

 mined the wave length of the auroral line to be 

 55.78 instead of 55.71, the previously accepted 

 value. This new value shows a further departure 

 from any known substance than does the old. 

 The auroral line shows in the spectrum, no matter 

 what part of the heavens the camera is pointed 

 at; it is, however, weakest near the zenith. Lord 

 Rayleigh, the great English scientist, is now at 

 work upon this problem of the auroral line in the 

 spectrum, the object of this study being to gain 

 additional information concerning the upper 

 limits of the earth's atmosphere. The work of 

 Dr. Stuerman, a Norwegian scientist, who has 

 spent many years in the study of auroral phe- 

 nomena, shows that most of the auroral streamers 

 take place about 100 kilometers above the earth's 

 surface, but some are as high as 500 kilometers. 

 If we can learn what the auroral line corresponds 

 to, our knowledge of the upper limits of the 

 earth's atmosphere will be greatly increased. The 

 author showed many photographs taken with a 

 hand camera, of the remarkable auroral display 

 of May 14, 1921, the most brilliant ever noted at 

 the Lowell Observatory. 



Observations on the magnetic storm of May 14, 

 19S1: William Cullom. Mr. Cullom described 

 briefly the U. 8. Magnetic Observatory and the ap- 

 pliances used, noting especially the variometers 

 which records the horizontal and vertical intensity 

 of the earth's magnetic field. He discussed quiet 



daj's — or days of normal magnetic activity — and 

 disturbed days — or days of magnetic disturbance; 

 and exhibited a typical variometer record of each. 

 He described how the great magnetic storm of May 

 14, 1921, was preceded by a violent preliminary 

 disturbance and the storm proper was divided into 

 three phases — one from 6 P. M., May 13, to 4 

 A. M., May 14; another from 3 P. M., May 14, 

 to 2 A. M., May 16 ; and the third from 3 P. M., 

 May 16, to 5 A. M., May 17. The two last were 

 about equal in violence; the first Avas less violent 

 than the other two. 



. Report of a daylight meteor seen in Prescott, 

 Arizona: Milton UpDEORArr. The author men- 

 tioned a report which reached him in tJie spring 

 of 1921 of a meteor which passed over Prescott 

 from the east to the west, and of such brilliancy 

 that it was plainly visible about noon. He him- 

 self did not see it, but was told of it by several 

 reliable people. Later reports reached him which 

 led him to believe that the meteor struck in the 

 neighborhood of the Harcuvar Mountains, in 

 Mohave County, somewhat southwest of Prescott, 

 and 30 or 40 miles from the California line. He 

 mentioned the advisability of having a search 

 made of that region, to try to find some traces 

 of the meteor on the place where it struck. 

 Biological 



The presci-vation of natural areas in the na- 

 tional forests: G. A. Peaeson. The writer was 

 requested by the chairman of the Committee of 

 Preservation of Natural Areas of the Ecological 

 Society to list the areas of the national forests 

 of Arizona and New Mexico where plant and 

 animal life and natural features in general may 

 remain undisturbed by human activities. Within 

 these two states are 15 natural forests whose 

 combined area is nearly 22 million acres. Under 

 the existing methods of management it is inter- 

 esting to consider whether the national forests 

 will answer the requirements for ' ' natural areas. ' ' 

 The general policy governing the handling of 

 national forests is that of highest use to the 

 public. The primary purpose is the production of 

 timber and associated with this is the utilization 

 and development of grazing, agriculture, water, 

 mining, recreation and other resources. One or 

 two areas, even though of large size, would prob- 

 ably not represent a sufficient variety of condi- 

 tions to satisfy foresters and botanists. Their 

 needs could be met by selecting small supple- 

 mentary areas of from 80 to 640 acres. 



The relation of research to agriculture: T>. W. 

 Working. A reaffirmation of the necessity for 



