886 



SCIENCE 



[N. S. Vol. XXXII. Xo. 833 



Solar Disturbances and Terrestrial Temperatures : 



W. J. Humphreys. 



Observations appear to show that earth tem- 

 peratures are greatest at times of sun-spot 

 minima and least during spot maxima, and the 

 natural inference is that there must be at these 

 times corresponding differences in the solar con- 

 stant, though such differences have not yet been 

 observed through a spot cycle. At the time of 

 spot maxima the solar corona is most extensive, 

 and this must lead to a maximum in the scatter- 

 ing or diffusion of the radiation, and therefore to 

 a minimum in the amount of short-wave light 

 that reaches the earth, even though the total en- 

 ergy output may be the same. Now a change in 

 the violet and ultra-violet radiation that reaches 

 the cold dry oxygen in the upper atmosphere pre- 

 sumably alters the amount of this oxygen that 

 exists in the form of ozone, in the sense that the 

 greater this ozonizing radiation the greater the 

 amount of ozone. Further, since ozone absorbs 

 earth temperatures far better than the shorter 

 wave-length solar radiations, it follows that when 

 the ozone is in greatest abundance, or, as appears 

 from the above, during spot minima, there must 

 be an increase in earth temperatures. Tempera- 

 ture changes, therefore, that seem to indicate 

 variations in the solar constant may be caused in 

 part by changes in the spectral distribution of the 

 sun's energy. 



On the Solar Spectrum; Considerations based on 

 a Study of Rowland's Tables: H. F. New all. 



On the Variations of the Cyanogen Band at Wave- 

 length 3SS3 : H. F. Newall. 



Progress in Visual Observations of Variable Stars 

 at the Harvard College Observatory/: Leon 

 Campbell. 



The regular monthly observation of seventeen 

 circumpolar variables of long period was begun in 

 1888. Sequences were selected, estimated and 

 measured, and accordingly the magnitudes of the 

 comparison stars were deduced on a uniform pho- 

 tometric basis. In 1892, fifty-six more variables, 

 mainly of long period, were added to the list, and 

 sequences for these were treated in a similar 

 manner. Observations were made of these vari- 

 ables first by the method of Argelander and more 

 recently by the method of direct estimates. The 

 results of these observations up to 1906 are given 

 in volumes 37 and 57 of the Harvard Annals. In 

 1904 the observing list was extended to include 

 nearly all the variables of long period north of 

 declination — 25°, having a maximum brightness 



of 9.0 or brighter, and with a range of at least 

 three magnitudes. More recently the above 

 scheme has been extended to the southern sky, 

 and over a hundred stars are included. For the 

 ready and accurate identification and observation 

 of these four hundred and more variables, maps 

 have been made by enlarging sections of the charts 

 of the Bonn Durchmusterung and photographs 

 taken at this observatory; the excellent series of 

 charts of Hagen and of the Yerkes Observatory 

 have also been used. Twenty years ago an eve- 

 ning's work consisted of 15 to 20 observations, 

 whereas now 50 and occasionally 75 are made; 

 and the total number per annum has increased 

 fivefold. 



A Comparison of Magnitudes of Certain Stars in 

 the Oxford and Potsdam Astrographic Cata- 

 logues and in the Cape Photographic Durch- 

 musterung with Magnitudes on the Harvard 

 Standard Photographic Scale: H. S. Leavitt. 

 Photographs and Spectrum of Halley's Comet: 

 A. Fowu;e. 



The photographs exhibited were taken by Mr. 

 Evershed at Kodaikanal, India, the spectra having 

 been obtained by tlie use of a prismatic camera 

 of 2 inches aperture and 11* inches focal length, 

 with two prisms of 60°. The continuous spectrum 

 of the nucleus crossed by Fraunhofer lines was 

 clearly shown, together witli the gaseous spectra 

 respectively characteristic of the head and the 

 tail. Fraunliofer bands of carbon and cyanogen 

 were the chief features of the head, that of cyan- 

 ogen at X 3883 being especially intense, while the 

 bands of the tail were essentially the same as 

 those which appeared in Comets Daniel ( 1907 ) 

 and Morehouse (1908). The author gave an ac- 

 count of the experimental work which had led 

 him to identify the bands of the tail with the 

 spectrum of carbon monoxide at very low pres- 

 sures, and also to explain certain peculiarities in 

 the carbon bands in the head by the superposition 

 of a newly recorded " high-pressure " spectrum of 

 the same gas. 

 Recent Results concerning Eticke's Comet: Oskab 



Backlitnd. 

 Wave-length Formulae for Series of Lines in Spec-' 



tra: J. Rydbekg. 



Meteorological Observations in Connection vnth 



Halley's Comet: W. J. Humphbeys. 



This is a summary, made by Dr. Humphreys at 



the request of the comet committee of the society, 



of the atmospheric and other meteorological phe- 



