464 NATURAL SCIENCE. Jone, 
In the matter of handbooks, however, there is probably no 
country that has met the wants of the beginner and the skilled 
amateur so fully as England. Carpenter’s ‘‘ Revelations of the 
Microscope” has, in each of its seven editions, held its own not 
only in England and America, but has been largely used on the 
Continent. Nevertheless, and, perhaps, indeed for this very reason, 
there is no country in the world where the great Diffraction theory 
of Abbe, explaining the principles of vision with the modern micro- 
scope, has been so critically and, at the same time, so warmly and 
generally received asin England. At the same time, there are few 
working microscopists whose shelves are without Handbuch der 
Allgemeinen Mikroshopie by Dr. Leopold Dippel; and it may be safely 
predicted that the splendid Theorie dey Optischen Instrumente nach Abbe 
by Dr. Siegfried Czapski, which has just come from the publishers’ 
hands in Breslau, will anywhere find a more appreciative circle of 
students than in England; but the English microscopist, who is 
not only a student of what the microscope does and can reveal, but 
also a critic and connoisseur of the principles and modes of manufac- 
ture of the instrument, really needs books of the class above indicated. 
The day for handbooks that are better illustrations of the art of the 
printer and the wood engraver than of the science and art of 
microscopy has passed away. 
In the treatise now before us great pains has been taken to pre- 
sent in its most attractive form the facts of microscopical science as 
known to us ten or fifteen years ago, and to make an appendage to 
these of the most recent knowledge which has come to us as the 
result of theory and practice in more recent times ; but between the 
old and the new there is no coherence. The treatise purports to 
cover all the area of modern microscopy, in the interests and for the 
benefit of the amateur. That it fails of its purpose there can be no 
doubt. It does this partly because of its method. It adopts the 
older style of teaching, and simply forces the new optical doctrines 
and details of the new methods of manufacture and manipulation 
(where given at all) into a place or position in the text without pre- 
face or explanation. The result is that we obtain an account of the 
‘‘ Theory of Microscopic Vision” which is in itself excellent, but 
quite beyond the range of the class of reader for whom the book is 
ostensibly written, because, clear as Abbe is in the exposition of his 
great theory, it needs at least a chapter of explanation and introduc- 
tion to make it fully accessible to the ordinary, and especially the 
non-mathematical, reader. The result is, that this book appears to us 
to fail from the fact that it directs the student to go beyond his depth, 
without even the semblance of assistance on the one hand, and, on 
the other, guides him with great care over shallows where no guide 
was needed, save the catalogues of certain English and foreign 
opticians—that is, as to the forms of certain instruments mostly on 
the same type. 
It is quite true that the tyro wants above all things to know how 
wisely to purchase an instrument; but this is not unfolded to him 
by an indiscriminating description of the microscopes of certain 
makers however diverse, but by an unbiased description of the 
essentials of any good instrument, and such an account of practical 
tests as would enable a beginner at least to see how far a certain 
pattern of stand, or a specific instance of workmanship, answers to 
this set of requirements. And in furnishing these data there need be 
no more dogmatism than in an experienced photographer’s affirmation 
