1868. | Sir John Herschel and Modern Astronomy. 191 
in 1823 in the ‘Encyclopedia Metropolitana. In 1832, ‘A 
Treatise on Astronomy’ was published as one of the volumes of 
the ‘ Cabinet Cyclopzedia,’ which was subsequently enlarged into the 
‘Outlines of Astronomy, of which work the eighth edition was 
published in 1867. ‘The extensive popularity of this treatise will 
be judged of from the fact of its having been translated into 
Russian, Chinese, and Arabic. In 1831 this eminent astronomer 
was created a Knight of the Royal Hanoverian Guelphic Order 
(K.H.), and he became a baronet in 1838. In the interval Sir 
John Herschel visited the Cape of Good Hope for the purpose of 
carrying out a similar system of celestial observations to those 
pursued at home. It has been often stated that this expedition 
was undertaken at the cost of the Government: this was not the 
case. A passage in a king’s ship was offered to Sir John Herschel, 
but he declined to avail himself even of this, and the whole cost 
of the voyage and the expenses consequent on the removal of all 
his instruments were defrayed by himself. Four years were spent 
at Feldhuysen near the Cape of Good Hope. His labours in the 
Southern Hemisphere were published under the title of ‘ Results of 
Observations made during the years 1834-8, at the Cape of Good 
Hope, completing the Telescopic Survey of the visible Heavens, com- 
menced at Slough in 1825. This work was published at the expense 
of His Grace the Duke of Northumberland. The great object of 
Sir John Herschel was to discover whether the distribution of the 
stars in the Southern Hemisphere corresponded with the results of 
Sir William Herschel’s similar labours, prosecuted mainly on the 
opposite side of the Galactic circle. In order that the observations 
made at the Cape might admit of comparison with those made at 
Slough, they were made with a telescope of the same optical power 
and according to the same method. These observations embraced a 
region of the celestial sphere, extending from the south pole of the 
Milky Way to a distance of 150° measured upon a great circle passing 
through it. The whole number of stars counted in the telescope 
amounted to 68,948, which were included within 2,299 fields of view. 
It appeared from these observations that the Southern Hemisphere 
ig somewhat richer in stars than the Northern, and this is thought 
to indicate that the solar system is not situate exactly in the plane 
of the Galactic circle, but is displaced a little towards the North. 
M. Struve * remarks that the apparent position of the Milky Way 
presents an interesting accordance with this conclusion, for it has 
been found that its mean course does not coincide exactly with the 
great circle of a sphere, but with a parallel distant about 92° from 
the Galactic North Pole. By a computation, based on the star 
gauges in both hemispheres relative to the Milky Way, Sir John 
* « Ktudes d’Astronomie Stellaire.’ 
