Mat 15, 1908] 



SCIENCE 



767 



tions in accuracy; (&) errors found in 

 magnetic charts of the Pacific Ocean 

 amount to from 1° to 5° in declination (or 

 variation of the compass) and in dip, and 

 about .04 in the horizontal magnetic force. 

 The correction of such errors, especially 

 the error in declination, is of great im- 

 portance for the safe and rapid naviga- 

 tion of vessels. 



The Investigation of the Personal Error 

 in Double Star Measures which depend 

 on the Position of the Angle: Mr. Eric 

 DooLiTTLE, of Philadelphia. 

 This paper gives the result of the deter- 

 mination of the constant personal errors, 

 and also of the probable uncertainty of 

 the measures, of double stars made during 

 the past ten years at the Flower Astro- 

 nomical Obsei'vatory of the University of 

 Pennsylvania. Some eighty thousand 

 single measures are available for the in- 

 vestigation. The double stars observed are 

 divided into four classes and the law of 

 occurrence of error deduced for each class. 

 It is shown that for each class the personal 

 error is well determined, so that from 

 measures actually made the true value can 

 be quite approximately determined. 



Astronomical Photography: John A. 



Brashear, of Allegheny, Pa. 



Dr. Brashear spoke of the advantages 

 of the photographic over the visual method 

 of astronomical observation, and rapidly 

 sketched the history of the development of 

 astronomical photography, from the time 

 of Draper to the present. He also ex- 

 hibited a number of photographs of celes- 

 tial objects, such as star clusters, nebulae, 

 comets, the moon and planets, etc. ; a large 

 proportion of which were made with the 

 10-inch Brashear lens of the Bruce tele- 

 scope of the Yerkes Observatory. 



Relative Advantages of Various Forms of 

 Telescopes for Solar Research: George 



E. Hale, of Solar Observatory, Pasa- 

 dena, Cal. 



Professor Hale discussed different types 

 of telescopes for solar research, describing 

 particularly the equipment at the Solar 

 Observatory of the Carnegie Institution at 

 Mount Wilson, California. The advan- 

 tages of the fixed horizontal telescope with 

 heliostat were pointed out. The author 

 also described the large spectroheliograph 

 of this observatory and exhibited a num- 

 ber of examples of photographs taken by 

 means of this instrument, including solar 

 prominences, faculfe, and sunspots. 



Photographs of Daniel's Comet: E. E. 



Barnard, of the Yerkes Observatory. 



The comet was photographed on thirty- 

 eight nights with the Bruce photographic 

 telescope of the Yerkes Observatory. This 

 is one of the brightest comets that have 

 been visible since the great comet of 1882. 

 It was visible to the naked eye for about 

 two months during the summer. The pho- 

 tographs showed that the most active period 

 in the comet's history occurred nearly a 

 month before perihelion, at which time 

 changes occurred so rapidly that the ap- 

 pearance of the comet changed from night 

 to night. Indeed, on comparing the Yerkes 

 Observatory photographs with photographs 

 made at M. Flammarion's observatory in 

 France, and at the Lick Observatory on 

 the same night, marked differences in the 

 photographs could be seen. 



The Solution of Algebraic Equations in 

 Infinite Series: Preston A. Lambert, of 

 Lehigh University. 



The object of this investigation is to 

 develop a general method for determining 

 all the roots of any algebraic equation, by 

 means of infinite series. The method con- 

 sists in forming algebraic functions of x 

 from the given equation f{y) =0 by in- 

 troducing a factor x into all the terms but 

 two of the given equation. These algebraic 



