EE VIEWS. 
87 
that “ the structure of a comet, as seen in section in the direction of its 
length, must be that of a hollow envelope, of a parabolic form, enclosing near 
its vertex the nucleus and head.” There, too, the writer states that “ the 
luminous part of a comet is something in the nature of a smoke, fog, or cloud, 
suspended in a transparent atmosphere.” The remarks on the curious subject 
of the perturbations of Uranus, and the discovery of the planet Neptune by 
Adams and Leverrier, are of intense interest, and demonstrate to those 
unfamiliar with the principles of the science, the exactitude of the basal 
scheme which constitutes the foundation of Astronomy. 
Sir John Herschell’s Avork is illustrated by nine beautifully executed page- 
plates, which delineate the spots seen upon the sun and the willow-hand 
structure of the latter philosopher ; Mars, Jupiter, and Saturn ; the arrauge- 
ment of the lunar mountains ; one of the volcanoes of the moon, and various 
important comets and nebulse. In point of style the writing is occasionally 
defaced by sentences of too prolonged a character, but in other respects the 
volume is an excellent one ; and although we are far from thinking it is a book 
which may be placed in the hands of a mere beginner, still we believe that for 
those who have already acquired the iTidiments of the science, no better 
treatise can be found. 
HE past twelvemonth has been extremely prolific in the production of 
works on the microscope, and the method of preparing objects for micro- 
scopic examination. All that have come under our notice have been good in 
their way. Some have been devoted exclusively to the mounting of objects ; 
others to the characteristic structures of the tissues of plants and animals, 
when seen with the aid of microscopic apparatus. Now, however, a treatise 
presents itself, which combines all the student can possibly recjuire in the shape 
of information necessary to make him a good working microscopist. Ur. 
Beale has done good service in publishing a new edition of his treatise, and 
whether we regard the product of his labours in this direction from a savan’s , 
or a Avorker’s point of view, Ave must confess it is an excellent one. The 
volume opens with descriptions of the simple and compound microscopes, and 
of the various pieces of apparatus which belong thereto. In this portion of 
the text we find the more useful instruments of English manufacture have 
been carefully described and compared, and that the author, without giving a 
decided preference to any particular microscope, evidently leans towards that 
of Messrs. Powell and Lealand. In the chapters on the examination of the 
tissues there is much valuable matter, Avhich the student cannot acquire from 
other sources, and which betrays the very great practical experience of the- 
writer. Dr. Beale describes how a structure may be investigated under all 
possible conditions ; by refiected, transmitted, and polarized light, and how 
in adopting each of these methods, one may modify the result by the employ- 
ment of various appended apparatus. In these paragraphs we observe that 
* “ How to Work with the Microscope,” by Lionel S. Beale, M.B.^ 
P.K.S., Professor of Physiology in King’s College, London, &c. Third 
edition. Pp. 272. London : Harrison, 1865. 
MICKOSCOPIC MANIPULATIONS 
