146 Mr. W. Huggins and Dr. W. A. Miller on the [May 17, 



with bibulous paper ; upon the desired dew-point being attained, the 

 action ceases. 



The range of the instrument is regulated by means of a spiral spring at 

 one end of the tube, and an adjustable weight at the other. 



By means of a pencil attached to one of the levers, the instrument may 

 be made self-registering. 



An ordinary Mason's hygrometer is attached to the instrument for regu- 

 lation and comparison . 



With a variation of one degree in the moisture of the atmosphere, the 

 instrument is capable of supplying ten quarts of water per hour to the sur- 

 face of the pipes from which it evaporated. 



III. " On the Spectrum of a New Star in Corona Borealis^' ^. By 

 William Huggins, F.R.S., and W. A. Miller, M.D., Treas. 

 U.S. Received May 17, 1866. 



Yesterday, May the 16th, one of us received a note from Mr. John Bir- 

 mingham of Tuam, stating that he had observed on the night of May 12 

 a new star in the constellation of Corona Borealis. He describes the star 

 as "very brilliant, of about the 2nd magnitude." Also Mr. Baxendell of 

 Manchester wrote to one of us giving the observations which follow of the 

 new star, as seen by him on the night of the 15th instant. 



" A new star has suddenly burst forth in Corona. It is somewhat less 

 than a degree distant from e of that constellation in a south-easterly direc- 

 tion, and last night was fully equal in brilliancy to (3 Serpentis or y Her- 

 culis, both stars of about the 3rd magnitude." 



Last night. May 16, we observed this remarkable object. The star 

 appeared to us considerably below the 3rd magnitude, but brighter than e 

 Coronse. In the telescope it was surrounded with a faint nebulous haze, 

 extending to a considerable distance, and gradually fading away at the 

 boundary f. A comparative examination of neighbouring stars showed 



* The Astronomer Royal wrote to one of us on the 18th, " Last night we got a meri- 

 dian observation of it ; on a rough reduction its elements are — • 



R.A. 1866, May 17 15^53'° 56^-08, 



KP.D 63° 41' 53", 



agreeing pre^^isely with Argelander, ]S"o. 2765 of " Bonner Sternverzeichniss," declina- 

 tion -|- 26° magnitude 9-5." Mr. Baxendell writes on the 21st, " It is probable 

 that this star will turn out to be a variable of long or irregular period, and it may be 

 conveniently at once designated T Coron£e." Sir John Herschel informs one of us that 

 on June 9, 1842, he saw a star of the 6th magnitude in Corona very nearly in the 

 place of this strange star. As Sir John Herschel's position was laid down merely by 

 naked eye allineations, the star seen by him may have been possibly a former tempo- 

 rary outburst of light in this remarkable object. 



t On the 17th this nebulosity was suspected only ; on the 19th and 21st it was not 

 seen. 



