January 31, 1S08] 



SCIENCE 



163 



increase their previously known sizes, and 

 he located and described nebulous regions 

 situated in the constellation Sagittarius. 



5. In this paper Professor Lovett con- 

 structs a problem of three bodies possessing 

 exact transcendental solutions defined by 

 finite equations; these solutions reduce to 

 the Lagrangian solutions of the classic 

 problem of three bodies when the ideal 

 problem assumes the Newtonian form. 

 The paper is a part of an extended memoir 

 which is not ready yet for publication. 



6. Professor Stebbins giv€s the results of 

 a long series of photometric observations 

 of the well-known variable star Delta 

 Cephei. The measures were made with a 

 polarizing photometer attached to a twelve- 

 inch refractor. On each night 96 com- 

 parisons of the variable and companion 

 star were taken, the entire series compris- 

 ing more than 7,000 settingis. The observa- 

 tions were combined by the method of over- 

 lapping means, and the resulting light 

 curve shows two secondary fluctuations in 

 addition to the main variation in bright- 

 ness. No complete determination of the 

 variation in radial velocity has been made 

 for this star, and new measures with a 

 modern spectrograph would throw some 

 light upon the conditions that exist in this 

 interesting system. 



7. The authors connected a selenium 

 cell as one ai-m of the ordinary Wheat- 

 stone bridge, and an exposure of the cell 

 to light decreased its resistance and caused 

 a deflection of the galvanometer. One 

 observer would point the cell at the moon 

 and make an exposure of ten seconds, while 

 the other observer, situated in a separate 

 room with the remainder of the apparatus, 

 would read the galvanometer. From a 

 series of additional exposures on a standard 

 candle at different distances, the moon's 

 light was determined in terms of candle 

 power at 1 meter. A curve of the varia- 

 tion of moonlight with phase was shown. 



and from this was derived that the full 

 moon is approximately nine times as 

 bright as the half moon. It was also found 

 that the moon is brighter between first 

 quarter and full than in the correspond- 

 ing phase after full moon. 



Different cells gave discordant values for 

 the candle power of the moon, and it was 

 shown that this must be due to the differ- 

 ent color sensibilities of the cells. The 

 relative sensibility for different wave- 

 lengths was determined for each cell, and 

 it was found that no two of the cells had 

 the same color curve. In all cases there 

 is a maximum at about X 7,000, but the two 

 Giltay cells have each another maximum 

 near A 6,000. It was therefore concluded 

 that selenium cells differ much as do pho- 

 tographic plates as regards color sen- 

 sibility. 



For measures of starlight a special small 

 cell was obtained from Giltay, and by pla- 

 cing this cell in the focus of a 12-inch re- 

 fractor, it was possible to obtain galvan- 

 ometer deflections caused by the light from 

 bright stars. Some results of the first 

 night were given, the scale being 5 meters 

 from the galvanometer, and the deflections 

 as follows: 



star Magnitude Dofleetion 



Mars 9.0 m.m. 



o Tauii 1.0 3.4 



a Arietis 2.1 1.3 



;8 Arietis 2.8 0.8 



y Arietis 4.0 visible 



These measures were made with a 

 galvanometer which is not very sensitive, 

 and it is hoped that the accuracy of the 

 observations will be considerably increased 

 when a new and more sensitive galvan- 

 ometer is obtained. If it becomes possible 

 to eliminate the effect of several disturbing 

 factors, especially that of temperature 

 change, there is no doubt that accurate 

 measures of starlight can be made with 

 selenium cells. 



