BARNARD— SOME PECULIARITIES OF THE NOV^. 103 



ther than that they were variable. The erratic variation of the Hght 

 of Nova Persei, for two consecutive seasons, is shown in the accom- 

 panying diagrams. It will be seen that the extreme variation of the 

 star is about two magnitudes. The two lower sets of figures (J. D.) 

 are the Julian Day; those on the side are magnitude. These are on 

 Seares's scale. 



It must be borne in mind, however, that not all the novae become 

 variable stars on regaining their normal condition. Nova Lacertas 

 of 1910 (Espin), up to the most recent observations after its return 

 to its original brightness, is perfectly steady in its light, or if there 

 is any fluctuation it is too small to be detected by ordinary means. 



One of the first of the novae to be carefully studied with the 

 spectroscope was Nova Aurigae of 1891. This star was discovered 

 visually by Anderson in January of 1892. It was later found that 

 the Harvard College Observatory photographs showed it as early as 

 December 10, 1891.* Though it never became very bright, it gave 

 more information of the physical condition of these bodies than any 

 previous nova, mainly from the fact that the spectroscope, then but 

 fairly starting on its wonderful career, aided by photography, was 

 applied to the study of its light. We know nothing of the history of 

 this star before its appearance in 1891.* It has probably long ago 

 returned to its original brightness. There are some suggestions in 

 recent observations of it that it is now also variable. 



In its early stage, when in the decline from its maximum, this star 

 showed one remarkable feature that has not been repeated in any 

 other nova. In April of 1892 Mr. Burnham followed it with the 

 36-inch telescope of the Lick Observatory until it got too near the 

 sun for observation. When he last observed it, on xA.pril 26, it had 

 faded to i6th magnitude. Having passed the sun, it was found by 

 Campbell in August of the same year to have risen to 9^ magnitude, 

 and was a conspicuous telescopic object. It had apparently increased 

 its brightness by six or seven magnitudes. In again fading it does 

 not seem to have reached the low magnitude at which Mr. Burnham 

 had seen it in the last of April, 1892. It is now about 14th or 15th 



* A photograph taken by Dr. Max Wolf at Heidelberg, Germany, on De- 

 cember 8, 1891, shows nothing in the place of Nova Aurigse as bright as the 

 eighth magnitude. The star, therefore, must have made its appearance be- 

 tween December 8 and December 10, 1891. 



