Catalogue of 209 New Double Stars

✍ Scribed by Prof. G. W. Hough

• Book ID: 102754171
• Publisher: John Wiley and Sons
• Year: 1887
• Tongue: English
• Weight: 1020 KB
• Volume: 116
• Category: Article
• ISSN: 0004-6337
• DOI: 10.1002/asna.18871161801

✦ Synopsis

I n t r o d u c t i on.

The double star observations which follow comprise 2 0 9 new pairs, of which 550 measures have been made. The work in this direction has. been done at irregular intervals, at such times when the planet Jupiter, or other special objects, did not occupy the time of the observer.

T h e E q u a t o r e a l . 'I'he equatoreal was constructed by Messrs. Alvan Clark and Sons and has a focal length of 23ft. and a clear aperture of I 81/2 inches.

'I'he tube is of mahogany, mounted after the German style.

The polar axis is suppcrted by a cast-iron frame resting on a single block of stone 8*/2 ft. in hight.

The right-ascension circle is 20 inches in diameter, divided to 30 seconds of time, and read by two microscopes to single seconds.

'The declination circle is 30inches in diameter, divided to 5' of arc, and read by two microscopes to 10" of arc.

On 'the rim of each circle, coarse divisions have been painted for quickly pointing the telescope. The rightascension may readily be set within one minute of time, and the declination within 5' of arc.