422 
Analyses of Books. 
FJuly, 
bibliography has received great attention, and references are given 
almost to the date of publication. Taking the article “ Angular 
Aperture,” for instance, notice is taken of the diffraction theory of 
Abbe, which so entirely demonstrates the true function of aper- 
ture, although the prominence given to it is hardly so great as is 
needed for so negleCted, but yet important, a subject. References 
are, however, given to the most recent papers on the subject. 
Turning to Coal, the process for softening, by maceration in a 
solution of carbonate of potash, so that, as it is stated, sections 
may be cut with a razor, which has appeared in every edition, is 
still printed : the process has been tried frequently, without the 
least success. Surely the paragraph should be expunged, or an 
explanation given if it only refers to some particular kind of coal 
or lignite. 
Many additions have been made to the illustrations, A very 
beautiful coloured plate of Rock sections, after drawings by Frank 
Rutley, is very welcome. Petrology is a branch of Science which 
has made gigantic strides : the microscope and polariscope have 
here done wonders Doubtless the subject will receive due atten- 
tion in its proper place in the book. 
With so small a portion of the work published it is difficult to 
know the exaCt extent of the change contemplated. Some of 
Tuffen West’s beautiful engravings, which formed so prominent 
a feature in former editions, are still retained. It is to be hoped 
that a more correCt representation of the Proboscis of the Blow- 
fly than the old one on Plate 33 may subsequently appear : it is 
correCt as far as it goes, being a true representation of the old 
flattened preparation ; but the researches of Lowne and others, 
on uncompressed specimens, have given more accurate views. of 
its structure. 
A good series of cross references is arranged, and will mate- 
rially help the student in finding the subject he is in search of, 
and, where space does not admit of so full an account as perhaps 
might be wished, the ample references to papers where fuller 
details can be found will supply the want ; indeed, with the great 
variety of subjects contained in the work, no other plan would 
be possible without making an already large book of unwieldy 
dimensions. So far as can be seen, the present edition promises 
to equal, if not surpass, its predecessors. 
Straggling Magnetic Lights .* By Philipp Walburg Kramer. 
Breslau. 
We have in this pamphlet vehement attacks upon medicine as 
taught and practised by the scientific physicians of the day, and 
* Magnetische Streiflichter, 
