18 



ever, must be considered only transitory, for many times since 

 that period the star has not reached more than the 6th mag- 

 nitude, and may be so estimated at present. The accompany- 

 ing drawing was made with an inverting eye-piece, and taken 

 75° east of the meridian to prevent the unpleasantness of 

 taking it near the zenith. If, therefore, the line of sight is 

 brought to correspond with the south of the Cape Monograph 

 the position of both drawings will be made approximately to 

 agree at the time they were taken. In conclusion, I would 

 observe that the particular interest taken in this object is 

 owing to the star's inequality of motion, as to magnitude, and 

 fluctuations in the nebulous mass. There are o'n record very 

 many variable, as well as binary stars, whose change in mag- 

 nitude and periods are correctly known. If we take the star 

 « Centauri, not far from -n Argus, the binary period is 78 years, 

 or a little more than 4J° annually. R Leporis is Hinds' cele- 

 brated intense crimson star, max. 7, period 400 days. E. 

 Leonis is a ruby star, max. 5, min. 10, period 324 day. i^ 

 Oephei, fine deep garnet star, max. 3, min. 6, period 6| years, 

 j8 Persei moves from max. 2 to min. 4, period 2.86727 days. « 

 Hydrae has a period of 55 days, &c. The period that has 

 been given to -n Argus is 46 years, and its variability from 1 

 to 4. This we have seen, however, is not correct, since the 

 time of Halley in 1677 we have passed over 191 years, and not 

 arrived at either the variability or period of v Argus, and for 

 anything known it may disappear altogether : there are stars 

 of that class on record. In 1604 a new star appeared in the 

 east foot of Ophiuchus, but disappeared again in 1605, it was 

 as bright as Venus and lasted but 15 months. In 1600 Kepler 

 discovered a new star v in Cygnus, which he observed for 19 

 years, it faded away and then blazed out again several times 

 before its final disappearance in 1621. With respect to the 

 fluctuations that are taking place in the nebulous matter, it 

 scarcely requires to be premised, that on a subject of this 

 nature, the highest evidence that can be attained is a degree 

 greater or less of probability. The only speculation to unfold it, 

 which has hitherto thrown any light upon what is so legiti- 

 mate and urgent a physical inquiry, constitutes the remarkable 

 Nebular Hypothesis of Laplace. 



