Gore — On Suspected Variable Stars. 269 



Compound characters, expressing the wavering of star-light, as 

 follows : — 



i From the least perceptible difference less bright to equality. 



I From equality to the least perceptible difference more bright. 



T From a very small difference more bright to the least percep- 

 tible difference. 



= , From -, to - etc. 



i The wavering expressed by the passing of the light from a 

 state of the least perceptible dijfference less bright to 

 equality, and to the least perceptible difference more 

 bright. 



T The wavering expressed by the change from - to , and to . , 

 or from • to , and to - . Professor Pritchard finds that 

 . = 0-09 mag. ; , = 0-19m., and - = 0-40. 



Dr. Gould's magnitudes of the stars, observed at Cordoba, as given 

 in the Uranometria Argentina, are of especial value, as they are the re- 

 sults of the independent observations of four observers, and any future 

 change of light in a star to the extent of even half a magnitude can 

 hardly escape detection by careful comparison with neighbouring stars. 



A few nebulae suspected of variation have also been inserted in the 

 Catalogue. 



I have added my own observations of a considerable number of the 

 stars in the Catalogue. Those previous to October, 1877, were made 

 in the Punjab, India, and the remainder in Ireland. These obserA^a- 

 tions were chiefly made with a binocular, or field-glass, by Browning, 

 London, having object-glasses of 2 inches diameter, and a magnifying 

 power of about 6 diameters. With this glass, stars to about 9 m., or 

 fainter — when not close to brighter stars — can be readily discerned in 

 a clear sky, in the absence of moonlight. In comparing the relative 

 brightness of stars, I have always found it the best plan to accurately 

 focus the field-glass. Some observers put the glass slightly out of 

 focus in making their observations, and consider that in this way the 

 influence of colour on the eye is, to a great extent, eliminated. With 

 reference to this method, Dr. Gould says ( Uranometria Argentina, note 

 to I Carinse, p. 252) : " The results are not very satisfactory, owing in 

 part to the circumstance that many of the comparisons were made by 

 putting the opera-glass out of focus, a method which our experience 



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