446 
NATURE 
[April 6, 1871 

South. But on its arrival at his Observatory it was found to | 
have suffered so much that it actually fell to pieces! Only a few 
of the more massive parts were entire ; and of the rims of the 
circle nothing remained except that which carried the divisions, 
which, as I was informed by Troughton, was of ‘* Dutch brass,” 
and was quite unchanged. 
The excellence of this Dutch brass is, I believe, recognised 
also by watchmakers, and it seems to deserve inquiry to what its 
superiority over English brass is to be attributed. 
It is worthy to be mentioned that among the instruments 
ordered from Ramsden by Usher was an equatorial telescope 
driven by clockwork. But owing to Ramsden’s feud with Usher, 
this was not executed ; and this important aid to the as!ronomer, 
which had been proposed by Hook nearly a century before, lay 
dormant till it was applied by Frauenhofer, forty years later, to 
the Dorpat telescope. aT Ree ik 
Armagh 
Morell’s Geometry 
IN answer to your criticisms on my work, ‘‘ The Essentials of 
Geometry,” I have given an explanation as to the sources of that 
book. I proceed to give very briefly my arguments for what is 
there advanced. 
I shall do so under two heads, which will be in the form of in- 
dictments against my reviewer. 
For I charge him, first, with overlooking the nature and object 
of the book ; and, secondly, with overlooking the context of 
passages he criticises, an omission that changes the entire aspect 
of the case. 
First it is explained (Preface, p. vii.) that my little volume is an 
attempt at a manual and memento for students, of which so many 
exist in France and Germany. It is notorious that such works 
do not dispense with others, or touch the plan of school text- 
books, and then much of their contents consists of results with 
hints of demonstrations. Then at p. viii. of Preface it is added 
that an inspection of the methods empleyed will show that 
German and French geometricians . . do not condemn the 
student to keep a geometrical figure rigidly in the place in which 
it is laid down on paper. evolution and superposition are 
allowed . . . simplifying and shortening the proof, &c. 
Passing to the second indictment, I find that the criticism 
levelled against my so-called theorems of parallels commits two 
serious offences. First, it garbles my matter ; secondly, it over- 
looks the principles first laid down in the preface, applying from 
logic two propositions treated by me both manually and logic- 
ally ; thirdly, it overlooks claims in pp. 15, 24, 25, where the 
technical terms in p. 20 are explained; lastly, it ignores the 
fact that all our theorems about parallels rest on assumptions and 
not on logic. 
It is evident that if superposition be allowed, two parallels 
as they cannot cut (hyp.) must coincide, thus the angles they 
form with a secant will be equal. 
Again, the charge of want of logic in my proof of the inequality 
of triangles with three equal sides falls to the ground, if the first 
clause of p. 44 be read. For as this is a case of superposition by 
making the bases coincide, the arms of both triangles must coin- 
cide as radii of equal length intersecting at only one point on the 
same side of the base. The proof is equally direct from sym- 
metry, from inversion and juxtaposition, and from subposition, as 
in the Notes to Todhunter’s School Euclid. 
As to the critic’s difficulties about explaining the coincidence of 
two semicircles, to any one used to the free handling of geometri- 
cal figures in France and Germany, the thing wears a ludicrous 
aspect. 
Then about the statement that two equal adjacent dihedral 
angles are right angles, a moment’s reflection shows that if a 
dihedral angle be defined (Bos. p. 32) as an angle formed by the 
revolution of a movable plane at its common section over a sta- 
tionary plane, when it reaches the point where the two adjacent 
angles are equal, they must be right angles. The definition may 
be disputed, but the conclusion is correct. 
As regards the criticisms on my definitions, I do not think it 
necessary to enter into this matter. The ground of definitions is 
a wide and a disputed one, and Iam content to err, if err I do, 
with very high authorities. Euclid has defined a straight line to 
be that which lies evenly or equally between its extreme points. 
This definition affords no assistance in arriving at the properties 
of straight lines, In Dr, Simson’s edition, a point is defined to 
be that which has no parts or no magnitude. This is objec- 


tionable, as being wholly negative. Again Dr. Simson, in the 
notes to his edition of Euclid, admits that the 11th axiom is not 
self-evident. 
In conclusion, the reviewer is of course as likely to attack the 
fre> treatment of theorems and problems practised, especially in 
G-rmany, by the conception of the generation of all figures from 
their elements by the movement of points and lines. But it can 
scarcely be charged against the author of the ‘‘ Essentials” that he 
has not shown some of these shorter methods of demonstration 
as used in France and Germany. 
The nature of revolution is fully illustrated at pp. 6, 8, and the 
treatment of angles as ratios in note 2, p. 9. Our limits prevented — 
anything more than indications, but verbum sat. to the great 
logicians of England. J. R. MoRELL 
“ Britain ” 
HAVING been from home, I did not see the letter of ‘A. H.” 
in your publication of March 16 until yesterday. His only ob- 
jection to my derivation of the name Srifain is that the word fa 
in his opinion was ‘‘ not used in this island so early as the argu- 
ment for its forming part of the word Srifam requires. The 
following remarks will show that it #zs¢ have been used in this 
island quite as early as the word Britain. 
His assertion that ‘‘ our word “7 is of comparatively modern 
formation,” cannot be established. It #ust have been familiar 
to the Cornish centuries before Diodorus Siculus described St. 
Michael's Mount, in Cornwall, under its name of /é¢in, from 
whence tin was exported by the Phcenicians as far back as the 
time of Moses (Numb. xxxi. 22) ; and from none but the Phee- 
nicians could the Cornish have derived the word ¢—for that 
metal, as well as its name, was unknown to them before they 
were visited by the Phoenicians. The name /ééz (Tin-port) by 
which the Mount was called in the time of Diodorus, proves the 
existence of the word ¢ prior to that period, and the present 
Cornish word s¢é27 can only be acorruption of the very ancienuly 
adopted word 4 —a corruption arising probably during the 
Roman period, so that instead of / being a corruption of the 
Welsh ystaen, or of the Latin stannum, as ‘A. H.” imagines, 
the reverse is evidently the case. 
Assuming, with most authors, the original Phoenician word to 
be dz, that name continues unchanged in the Saxon, English, 
Dutch, Danish, and Icelan:lic languages ; but the Swedish name 
is now én; the German, zzz; the French, é¢aiz and fain ; 
the Latin, séaznwm; the Italian, stagvo ; the Spanish estano ; 
the Portuguese, estanho; the Irish, san; the Welsh, ystaen ; 
the Cornish, steaz ; the Armoric, sfeaz and also staen—the ini- 
tial letter or sound s in each of the last nine names being a mere 
prefix, as in the modern word sweeze for neeze (Job xli. 18). With 
this exception, and except the ordinary terminations of the Latin, 
Italian, Spanish, and Portuguese names, these thirteen different 
spellings are merely the different ways in which different nations 
of Europe pronounce the Pheenician word f77. 
Diodorus speaks of /é¢/n as an island adjoining Britain ; and 
this island (for it 2s anisland two-thirds of the day) was no doubt 
long before his time called sometimes /é/ and sometimes 
Bretin ;—Iktin when it was regarded as a ‘‘ port,” and Bretin 
when regarded as a ‘‘ mount ”—7é being the Cornish for “* port,” 
and dre the Cornish for ‘‘mount.” It was however most gene- 
rally known as a mount, and as the most remarkable object in 
Mounts Bay, to which it has therefore given its Zg/ish name, 
having long before the Christian era, in all probability, given its 
ancient Cornish name of Sveti to the island in which we live. 
Plymouth, March 29 RICHARD EDMONDS 
On the Derivation of the name 

Records of European Research 
Tue Chemical Society has taken up a good cause, that of re- 
porting foreign labours much more fully than could be worth the 
while for any periodical publication to undertake. 
I have suggested in another quarter the advisability, if possible, 
of joining in this scheme. But funds are requisite to have the 
work well done. 
It has struck me that, as a matter of completeness and economy, 
it would be far better if the learned societies subscribed, and the 
Royal Society made a grant besides its subscription, to engage 
an efticient staff to report foreign contributions not merely to,one 
branch of science, but to all, forming, let us say, a quarterly 
comptes vendus of European research, 
