April 25, 1913] 



SCIENCE 



641 



each plate. They will then be sent to Kapteyn, 

 who will supervise their measurement and reduc- 

 tion. If the entire plan can be carried out, the 

 catalogue will contain eight hundred thousand 

 stars, or more, and will fill at least ten volumes 

 of the Harvard Annals. 

 The Scale of the Yerkes Actinometry : J. A. Park- 



HURST. 



A new determination of the absolute scale for 

 the photographic magnitudes of the Actinometry 

 indicates that the published scale may be too ex- 

 tended by an amount not exceeding six per cent. 

 The original scale was obtained from sensitometer 

 images impressed on the plates with exposures of 

 10 to 20 seconds. The star images had exposures 

 of 5 and 25 minutes. An extended series of new 

 sensitometer exposures ranging from 5 seconds to 

 34 minutes indicated that the gradation was 

 steeper for the exposures of 5 minutes and longer, 

 than for the exposures in the neighborhood of 10 

 seconds. No difference was found for exposures 

 of 5 and 25 minutes, and this was confirmed by 

 422 pairs of images of white stars on the zone 

 plates. The application of the correction of — 6 

 per cent, brings the magnitudes into better agree- 

 ment with Harvard and leaves the differences with 

 Giottingen the same in amount but with the sign 



The Color Scale of the TerTces Actinometry: J. A. 



Parkhurst. 



A calibration of the color-sensitive plates used 

 in obtaining the ' ' visual ' ' magnitudes of the 

 Actinometry makes it possible to express the vary- 

 ing effect of light of different wave-lengths in 

 difference of stellar magnitude. The spectral in- 

 tensity curve is nearly symmetrical and has its 

 maximum at wave-length 5350. The absence of 

 selective absorption in the U-V glass of the Zeiss 

 doublet was shown by comparison of spectra taken 

 direct and through the glass. 

 On B Lyrce with a Three-prism Slit-spectrograph : 



Sebastian Albrecht. 



This paper gave the results of a study of two 

 series of three-prism spectrograms, twenty-five 

 plates in all, taken at the Lick Observatory. 

 Following is a summary of the principal results: 



1. The radial velocity of the star is — 27.22 km. 

 per sec. 



2. No periodic variation of radial velocity was 

 found. If such a variation exists, the double 

 amplitude of variation must be less than IJ km. 



3. Wave-lengths were determined for about 600 

 spectrum lines, between X 4150 and \ 4700 it. 



4. The individual spectrum lines showed no large 

 periodic shifts. 



5. Hx showed definite variation in intensity, 

 though the data available are insufficient to rleter- 

 mine definite connection with phase of light-varia- 

 tion. 



6. The wave-lengths of the lines in R Lyras, a 

 star of irregular light variations, are in good 

 agreement with the wave-lengths of lines ia the 

 M type stars. 



7. A preliminary test of this star for spectral 

 type, according to the method published in the 

 Astrophysical Journal, March, 1911, places it at 

 a somewhat "later" type than Mb, the type as- 

 signed to it in the Draper Catalogue. 



A New Form of Printing Chronograph: William 



Gaertner. 



This paper described in detail an instrument for 

 recording time in minutes, seconds and hundredths 

 of seconds, printing the records in figures on a 

 strip of paper. The instrument is used in connec- 

 tion with a clock or chronometer fitted with an 

 electric seconds contact, which operates the rr'nnte 

 and second type wheels and controls the speed of 

 the 0.01 seconds wheel. 



The minute and second wheels are rotated by 

 two specially designed electro -magnets which op- 

 erate on pawls and ratchet wheels of 60 teeth. 

 The seconds wheel closes a circuit when it has 

 made a full revolution and operates the magnet 

 which shifts the minute wheel. Both wheels can 

 be turned independently by hand and set to co- 

 incide with the clock. The wheel printing the 

 0.01 seconds is automatically set to zero by the 

 clock circuit and control magnet. 



The control of the hundredths of seconds is not 

 made directly on the type wheel, but by means of 

 a ratchet wheel of 100 teeth, and an iron pawl 

 engaging in it. The ratchet wheel is driven by a 

 separate weight driven clock work, regulated by 

 an improved form of conical pendulum friction 

 governor. This regulator is set to run a little fast. 

 When it has gained 0.01 second the control magnet 

 operated by the observing clock will disengage the 

 pawl and drop it in the next tooth of the ratchet 

 wheel, bringing the type wheel again in adjust- 

 ment. In practise the governor is adjusted so 

 that the regulator gains about li second per hour 

 and therefore the control will take place about 

 every 24 seconds. 



The printing of the time records is accomplished 

 by an electro-magnet which operates the printing 



