
_—”. 


Nov. to, 1870] 
NATURE 
25 

cal America from which herbaria, both in England and on 
the Continent, have been inore bountifully supplied. The 
consequence is, that out of this 180 we do not think that 
more than from twelve to twenty species are really new, 
in any sense in which we understand in this country what 
is meant by a species. For instance, we have some seven 
or eight species elaborately characterised and figured from 
what cannot be called anything else than so many indi- 
vidual fronds of that most cosmopolitan of ferns, our 
common English Asfidium or Polystichum aculeatum. 
Or, to take one of the exclusively Brazilian species, Cya- 
thea Gardneri, a very distinct tree-fern, is included in 
the list under five different names—Gardnervz (Dr. Gard- 
ner’s number on which Hooker described the species 
quoted), zzcurvata (a name of Kunze’s published in the 
Linnea from Regnell’s specimens), mamzllata, taunay- 
stana and attenuata, the last three new species here named 
and figured for the first time ; but the figures, beautiful as 
they are, might, any of them, have been drawn from Gard- 
ner’s specimens. The author does not seem to have any 
knowledge of numerous English and German books and 
papersin which Tropical American ferns are described, as 
for instance, Grisebach’s excellent Flora of the British 
West Indies ; and this leads to further name-crossing. In 
short, although one cannot but admire the excellence and 
the copiousness of the illustrations in these memoirs, and 
ought not to leave out of sight the example of devoted- 
ness to science which they show, expenditure of time 
devoted to one object through a long course of years, and 
of money, only a very small proportion of which their sale 
can possibly repay, yet still the predominant feeling on 
the mind must needs be that to deal with plants in this 
way has a direct tendency to bring species-botany at a 
very rapid rate into a state of utter confusion. 
J. G. BAKER 
The Laboratory Guide. A Manual of Practical Chemistry 
for Colleges and Schools, especially arranged for Agri- 
cultural Students. By A. H. Church, M.A., Professor 
of Chemistry in the Royal Agricultural College, Ciren- 
cester. Second edition, enlarged and revised, pp. 170. 
(London: Van Voorst, 1870.) 
THIS little book, as its title indicates, is intended mainly 
_for the use of students of agricultural chemistry, and 
we fear it might cause disappointment to anyone who 
wished to employ it as a guide to general analysis. The 
science of chemistry is so rapidly increasing, that it would 
seem almost hopeless, at the present time, to give students 
a complete knowledge of chemistry and leave them to 
apply their information to the special subject they intend 
to follow. Professor Church’s book is intended to obviate 
this difficulty, and after a few introductory lessons of uni- 
versal application, the student commences experiments on 
materials with which he is certain to come in contact in 
agriculture, such as superphosphate, milk, soils, &c. Part 
I. treats of chemical manipulation, and consists of a 
number of lessons intended to accompany the course of 
lectures, and from which the student will learn the mode 
of performing some simple operations, as solution, filtra- 
‘tion, crystallisation, specific gravity, and will become ac- 

quainted with the modes of preparation and properties of | 
the principal elements and compounds. 
commences with a list of the apparatus required, the 
ordinary reagents, and the special materials and tests 
necessary for the performance of the experiments, 
which are detailed with great clearness. This arrange- 
ment is calculated to cause the student to be careful to have 
everything ready before commencing work, and will thus 
save him much time and inconvenience, for few things 
are more likely to endanger the success of an experiment | 
than leaving it at a critical moment in order to obtain 
some piece of apparatus or reagent which should have 
been previously prepared. Part II. treats of qualitative 
analysis, of which Chapter I, deals with the elements, re- 
Each lesson | 

agents and tests, and reactions ; and here we find the terms 
univinculant, bivinculant, trivinculant, &c., as equivalent 
to monad, dyad, triad, &c. The principal distinguishing 
characteristics of the different groups of elements are here 
given. The section on reagents and tests will be found 
useful, for it contains the modes of testing for impurities, 
and indicates the strength of the different solutions em- 
ployed, two things to which attention should always be 
paid. The second chapter of this part describes the 
methods of qualitative analysis, all rare elements and 
those with which the agricultural student is not likely to 
meet being omitted. The third part is devoted to the 
general processes of quantitative analysis, and the fourth 
to the examination of manures, soils, water, and food. 
This book will doubtless be invaluable to agricultural 
students, besides being useful to those requiring special 
information on the subjects of which it treats. The 
appearance of such a work is a satisfactory indication of 
the extension of the application of scientific chemistry to 
the useful arts. 
The Book of the Roach. 
Field). 16mo. pp. 118. 
1870.) 
WHILST Mr, Pennell has instructed us in catching /ege 
artis all the various fish in British rivers and lakes, Mr. 
Fennell has been content to devote a little volume to the 
natural history and fishing of the Roach. Let no one 
smile at the man in the punt with his humble notions of 
enjoyment. Maybe he has been toiling hard the whole 
week in the noisy, murky town ; the quiet sport of the 
Saturday afternoon suits his purse exactly, and there will 
be real enjoyment over the dish of fried roach “ caught 
by father.” Nay, if we could measure the amount of 
pleasure, healthy recreation, and renewal of vigour ob- 
tained by the multitude in the unpretentious sport of 
roach-fishing, and compare it with that sought for by the _ 
select few who have the privilege of finding their amuse- 
ment on a salmon river, we should probably find the 
balance very much on the side of the former. No 
apology, therefore, was needed from Mr. Fennell. for the 
publication of his little book on the Roach. He has 
divided it into eight chapters, of which the first two are. 
devoted to the natural history of this fish, and the five 
following to a description of the tackle and various kinds 
By Greville Fennell (of the 
(London: Longmans and Co. 
| of baits, and to the methods of roach-fishing generally as 
| well as at certain localities. 
| given on the roach as an article of food, on the method of 
In the last chapter hints are 
cooking, &c. Aan 


LETTERS TO THE EDITOR 
[Zhe Editor does not hold himself responsible for opinions expressed 
by his Correspondents. No notice ts taken of anonymous 
communications. | 
Hypothesis regarding the Corona 
HAVING read in Nos. 34 and 35 of the valuable periodical 
NATURE (of June 23 and 30) the two articles about the Corona, 
I beg leave to direct your attention to an hypothesis concerning its 
nature, and especially the origin of the deams, which I sent to 
the Physical section of the Amsterdam Academy of Sciences, of 
which I have the honour to be a member. 
I have just received No. 1776 of the Astronomische Nachrichten, 
for October 15, where the American astronomer, Dr. Gould, in a 
notice regarding the total eclipse of the sun of August 7 (1869) 
says :— 
Xe Of the Corona I made some hasty measurements both with 
the telescope and without it. Its form varied continually, and I 
obtained drawings for three epochs at intervals of a minute. It 
was very irregular in form, and in no apparent relation with the 
protuberances of the sun, or the position of the moon. Indeed, 
there were many phenomena which would almost lead to the 
belief that it was an atmospheric rather than a cosmical pheno- 
menon, One of the beams was at least 30’ long.” 
