98 NATURE 
[Dec. 1, 1881 
arrangements for continuing these experiments at the 
Llwynpia Colliery of the Glamorgan Coal Company, 
where there is a large blower of natural gas. 
On the subject of the other source of danger they 
make the following observations :—‘‘ The use of gun- 
powder and other explosives is at the present day so 
widely spread, and is held by many to be so indispensable, 
that all suggestions for checking their application in cer- 
tain cases on account of risk need to be very carefully 
weighed.” “An overwhelming majority of our witnesses 
assert that it is practically impossible, as a rule, to work 
mines without powder.” They conclude however a re- 
view of the evidence on this subject with the following 
rather significant statement :—“ In the meanwhile it has 
appeared to us to be desirable to make trials of such 
methods of ‘ falling’ or bringing down the coal] as may do 
away with the danger caused by sparks and flame ; and 
with this view a series of experiments already commenced 
will be continued in different localities ’’ 
The result of these further inquiries and experiments 
with reference to lighting and blasting, it is of course im- 
possible to forecast. We fear it would be rash even to 
hope for an announcement that for the future fiery seams 
may be worked with a light, and brought down by an 
explosive, neither of which can ignite an explosive mixture, 
and both of which can be readily adopted without adding 
to the cost of getting the coal. But we await with much 
interest the conclusion of an inquiry which has been 
conducted in such a thoroughly scientific manner, and 
upon which so much practical experience, time, and 
labour have been bestowed. 
CELESTIAL OBJECTS FOR COMMON 
TELESCOPES 
Celestial Objects for Common Telescopes. By the Rev. 
T. W. Webb, M.A., F.R.A.S. Fourth Edition, revised 
and greatly enlarged. (London: Longmans, Green, 
and Co., 1881.) 
HIS is a new and much extended edition of a work 
which has attained considerable popularity amongst 
the many amateurs of astronomy in this country who are 
limited to the use of instruments of moderate optical 
capacity, or as the author terms them, ‘‘ Common Tele- 
scopes.” By this term are intended achromatics with 
aperture of from three to five inches, or reflectors of 
somewhat greater diameter, yet as telescopes of higher 
pretensions are now in the possession of private observers, 
the author in the selection of additional objects has aimed 
at including such as may be considered tests for a 
superior class of instrument. The increase in tele- 
scopic range applying chiefly to the sidereal branch of 
astronomy, the additions have been taken for the most 
part from the works of the Struves and Burnham for 
double stars, and Sir John Herschel’s catalogue for 
nebula: the total increase in the number of objects 
brought together in this new edition over the pre- 
ceding one, is stated to be about 1500. 
The first part of the work relates to the solar system, 
with a popular account of the actual state of our know- 
ledge of the characteristics of its various members, so 
far as they fall within reach of moderate telescopes. In 
treating of the sun, the author collects many cases of the 
observation of dark spots in motion upon the disk, in- 
cluding that recorded by Mr. Capel Lofft of Ipswich, in 
January, 1818, to which, if we mistake not, attention was 
first specially directed by Mr. Webb in an earlier edition 
of the present work. He reproduces Pastorff's drawings 
of what he supposed to be the great comet of 1819, in 
transit across the sun, on June 26, taken from the origi- 
nals, which are in the possession of the Royal Astrono- 
mical Society. The phosphorescence of the dark side 
of Venus, a phenomenon not as yet satisfactorily explained, 
is dwelt upon, as also the problematical satellite assigned 
to this planet. The moon is the subject of detailed 
description, the peculiarities of her surface, and the 
various craters, walled plains, valleys, clefts or rills, 
annular mountains, &c., are brought together in an inter- 
esting form; a map of the lunar surface forms the frontis- 
piece to the volume, and a full index to the five hundred 
spots marked upon it, with an “ Alphabetical Table of 
Lunar Nomenclature,” is amongst the contents: indeed 
our satellite forms the subject of special treatment, which 
is amongst the most notable and useful features of Mr. 
Webb’s work. An outline chart of the surface of Mars 
follows, with the actual nomenclature, which we hope at 
no distant time to see placed upon a more satisfactory 
foundation. The principal points of interest furnished 
by telescopic observation of the disks of Jupiter and 
Saturn are referred to, though, from the limited space at 
disposal, in less detail than the reader might perhaps 
desire. Cases of visibility of the brighter satellites of 
Uranus, and the satellite of Neptune, with telescopes of 
moderate dimensions, are recorded. 
After a brief notice of comets, the author passes to the 
main division of his work—sidereal astronomy, or, as he 
phrases it, ‘‘ The Starry Heavens,—Double Stars, Clusters, 
and Nebulz.” In this division, as it appears to us, Mr. 
Webb is at a disadvantage in being compelled to employ 
a system of abbreviation which, in the eyes of some 
readers, will not be without its disadvantage: but he has 
been perfectly aware of this, and in his Introduction asks 
the reader “to excuse a condensed form of expression, the 
result of necessity rather than of choice”; the amateur 
who intends to make practical use of the work must 
therefore accustom himself at the outset to Mr. Webb's 
abbreviations, and it must be admitted that it would have 
been difficult, without some such system, to have given 
the amount of information which is contained in the 300 
pages or less, devoted to stellar astronomy. Mr. Webb 
follows the convenient plan of taking the constellations in 
alphabetical order, so far as they are visible in these lati- 
tudes ; telescopic objects in the southern heavens are only 
noticed in a short appendix. The positions of the various 
objects are given to the nearest minute of time only in 
right ascension and the nearest minute in declination, 
but it may be remarked that the former is not a suffi- 
ciently close indication of the places of several interesting 
objects which fall well within the scope of observation of 
many amateurs, whom it might be desirable to enlist for 
their more systematic observation. We allude to cases 
like that of Tycho Brahe’s star of 1572, Kepler’s star of 
1604, or Anthelm’s in 1670. For the former the author 
gives R.A. oh. 19m., Decl. 63°24’ N., and recommends that 
a minute star near the place should be watched; but any 
one acquainted with the neighbourhood will know that a 
