372 
POPULAR SCIENCE REVIEW. 
with the two discovered by himself in 1851, are the only ones which accom- 
pany the planet. The two interior satellites last mentioned are very much 
fainter than the satellite of Neptune ; but he has had no difficulty in observing 
them even in moonlight. Many observations have been made of the satel- 
lites of Saturn. In measuring the distances of the satellites, Mr. Lassell 
finds that by noting the times when they have reached elongations ecpial to 
the semidiameter of the ring, the observations are more trustworthy than by 
makmg use of the micrometer. He thinks that if tliis plan were introduced, 
it would lead to a knowledge of the more exact dimensions of the rino-s and 
their eccentricities. A series of drawings have been made of Mars, and 
delineations of the more remarkable of the planetary and other nebulae, in- 
cluding one of the great nebulae of Orion. Several new nebulae have been 
detected by Mr. Marth. 
Nav Comets. — A comet was discovered by M. Baecker, of Nauen, on 
December 15, of the brightness of a star of the 7th magnitude. Its motion 
was direct, and it passed its perihelion on December 22. The fifth comet of 
1864 was detected at Leipsic on December 30, 1864, which passed its peri- 
helion on December 27, and the motion of which was retrograde. 
Itadiant Points of Shooting Stars. — Mr. Herschel observed carefully the 
above in September and October. One he found to be at K.A. 82°, with 
50° of N. declination, the other at R.A. 12°, and 2° of S. declination. The 
average time of duration of the first was 0‘71", and that of the latter 2T3" ; 
and from other considerations he assumes that their velocity was as 3 to 1. 
If their distances in their orbits from the sun were one-fourth greater or one- 
fourth less than that of the earth’s distance, this would be accounted for by 
theory. He therefore thinks, with Professor Newton and others, that the 
August and November rings of meteors very nearly coincide in their dimen- 
sions with the orbit of the earth. It also adds weight to the opinion, that 
their orbits are nearly circular, although it offers no explanation of their 
frequent retrograde motions and large obliquities to the ecliptic. 
Spectrum of Epsilon Piscium at the time of Occultation. — On January 4, 
1865, Mr. Huggins directed the telescope furnished with spectroscope to the 
above phenomenon, in order to detect, if possible, any symptom of a lunar 
atmosphere. If such existed, and absorbed any of the star’s light, this would 
be indicated by fresh dark Imes immediately before the star was occulted. 
If acpieous fog or invisible vapour existed, the blue rays would fade and the 
red ones be comparatively undimmed. If the lunar atmosphere were free 
from vapour, but rather dense, the blue end of the spectrum would continue 
visible after the red rays had disappeared. No change, however, took place 
in those respects. The spectrum disappeared (as if an opaque screen had 
passed over it) in two-tenths of a second. A few seconds before it disap- 
peared, some lines were perceived in the red rays, which might however have 
belonged to the star. The results of the observation are therefore negative, 
although Mr. Huggins is careful to guard against the idea that he thinks it 
conclusive. The care taken by Mr. Huggins, and his experience in those 
matters, are already well known by his spectrum observations on the planets 
and some fifty fixed stars, as well as on the nebulae. He has discovered some 
eighty lines in the spectrum of Alpha Orionis, in which only some dozen had 
previously been seen, whilst his observations on the spectra of the nebulae 
