Page:Philosophical Transactions - Volume 095.djvu/67

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of ascertaining the Magnitude of small celestial Bodies.

As far as the imagination will enable us to compare objects we see in succession, the magnitudes appeared to be in an arithmetical progression.

 

23d Experiment.

I examined α Geminorum with 410,5, and with the outside rays the stars were considerably unequal, and 11/4 diameter of the largest asunder. With all the mirror open they were more unequal, and 11/2 diameter of the largest. With the inside rays they were very unequal, and 17/8 of the largest asunder.

These experiments show that, if it had not been known that the apparent disks of the stars were spurious, the application of the improved criterion of the apertures would have discovered them to be so; and that consequently the same improvement is perfectly applicable to celestial objects.

 

observations on the nature and magnitude of mr. harding's lately discovered star.

It will be remembered that in a former Paper, where I investigated the nature of the two asteroids discovered by Signior Piazzi and Dr. Olbers, I suggested the probability that more of them would soon be found out; it may therefore be easily supposed that I was not much surprised when I was informed of Mr. Harding's valuable discovery.

On the day I received an account of it, which was the 24th of September, I directed my telescope to the calculated place of the new object,and noted all the small stars within a limited compass about it. They were then examined with a distinct high magnifying power; and since no difference in their appearance was perceivable, it became necessary to attend to the changes that