Aug. 25, 1870] 
NATURE 
337 
our globe, and the conclusion arrived at was, to ‘‘ grant the first 
rank to the internal, volcanic, or cataclysmic agencies, since, had 
it not been for their operations, our globe would still have re- 
mained a comparatively smooth sphere, surrounded by its ex- 
ternal envelope of water, with no visible land for the rivers to 
traverse or the rain and ice to disintegrate and wear away,” &c. 
In order that your numerous scientific public may not be led to 
judge of the lecture by this outline, I trust to your good will in 
asking you to insert these remarks in your next number. 
DAvip FORBES 
11, York Place, Portman Square, Aug. 22 
A Vivid Mirage 
THE illusion known as the mirage is, I believe, not unfre- 
quently observed in the British Isles; but the vividness with 
which it was displayed on the present occasion will, I trust, be a 
sufficient apology for troubling you with this letter. 
The land bordering the River Nene is protected by banks of 
from twelve to fifteen feet in height, enclosing a space called the 
** Wash,” which receives the flood waters. It was from one of 
these banks that the appearance in question was observed, nothing 
unusual being seen from the level of the fen. I may mention 
et the Wash at this season is as dry as any other portion of the 
and. 
The day (August 12) was hot, the sky cloudless, and a strong 
N.E. wind was blowing. About eleven o’clock the phenomenon 
was first noticed. To the eastward a dark line of trees, some 
eight miles distant, stood out in bold relief against the clear sky, 
and in front of this a shining line of silvery brightness was seen, 
which gradually widened until about twelve o’clock it presented 
the appearance of a broad expanse of water, ruffled into waves 
on its near side, but perfectly calm and clear toward the horizon 
where the line of trees was beautifully reflected on its surface. 
As I had been approaching the scene all this time, the expandinz 
of the lake appeared perfectly natural, and I could scarcely help 
thinking the river must have overflowed during the night and 
drowned the ‘‘ Wash.” This, of course, I knew to be quite out 
of the question, but the semblance was so perfect that it required 
an effort to believe that it was but an illusion. Its shores were 
clearly defined, little bays dimpled it, tiny headlands jutted out 
from it, and the waves were seen rising and falling with life-like 
exactitude. The whole appeared quite stationary, and as I 
approached the spot it gradually faded away, until nothing but a 
thin blue haze beneath the trees remained, and this at length 
dissolved. ; 
On looking behind me (7.¢. westward) another mirage seemed 
forming, which’ increased in apparent extent as I went farther 
from it. In this case the illusion was, if possible, more perfect 
than in the last, and the comparatively high land of Whittlesea 
rose like an island from the shining sea. Vehicles passing along 
the road seemed floating on its surface, their dark drawn-out 
reflections showing vividly against the sun-lit water, which, in 
this instance, was quite calm. How long this illusion lasted I 
know not, but when, about two o’clock, I quitted the bank it 
was still very distinct. 
The dead level of the fen, and the bright sunlight falling 
upon the parched land, from which the heated air rose tremulous 
as from a hot plate, render this district peculiarly favourable to 
the production of such effects. For the accuracy with which the 
appearance of water was simulated it was quite equal to any 
mirage I have witnessed on the African deserts. 
SyDNEY B. J. SKERTCHLY 
Geological Survey, Whittlesea, Cambridge, Aug. 12 
Mirages made Easy 
THE very interesting account of a mirage in this week’s 
NATURE induces me to send a few observations. The mirage 
phenomenon is by no means so uncommon in England as many 
think. Three or four summers ago, on astrip of sand three 
miles long at Morecambe Bay, I was able to see ane almost every 
hot day, by simply stooping until my eyes were about a yard 
above the ground. The further part of the sand then appeared 
as a lake of water, with objects reflected, &c. The nearer edge 
of this lake receded as the eyes were raised, the whole soon 
pecoming invisible. I saw the same effects last summer off the 
Holdemess Coast, but again only by stooping. At Cambridge 
T have lately seen a very good lateral mirage, by looking closely | 
along the surface of a wall fifty yards in length, which had been 
exposed for some hours to a western sun, Objects near the 
further end of the wall were distinctly reflected. 
Cuas, T, WHITMELL 
Trin. Coll. Cambridge, Aug. 4 
Science and the Government 
THE announcement in your last number of a rumour that the 
Government is about to withdraw its promise of aid to the 
Total Eclipse Expedition, seems to bring to a climax the relations 
of the Government towards science. We can hardly forget 
that one of the prominent members of the present ministry, and 
the one considered to have the special control over the spending 
of the public funds, is member for the University of London. 
Mr. Lowe was sent to Parliament, irrespective of party consi- 
derations, as the representative of a body which thinks it has 
some claim to a leading place among the scientific institutions 
of our country. Is it not worth while to consider whether the 
views of the graduates of London University are represented in 
the present attitude of the ministry, and whether some repre- 
sentation might not be made to the Government, through the 
Chancellor of the Exchequer, of the manner in which the 
present relations between the Government and science are re- 
garded by his constituents ? 
3, Park Village East, Aug. 20 ALFRED W. BENNETT 
AROMATIC GLYCOL* 
fe chemists recollect the profound impression caused 
by the discovery of glycol in 1855 by M. Wurtz. 
Up to that time the bodies which were recognised as be- 
longing to the group “alcohol” only included what we 
now call monatomic alcohols (common alcohol and its 
analogues), and M. Berthelot hesitated before venturing 
upon declaring glycerine a triatomic alcohol—an opinion 
to which Gerhardt never entirely adhered. 
M. Wurtz showed that besides ordinary or monatomic 
alcohols, there are others which, when submitted to certain 
reagents where ordinary alcohols furnish only one, pro- 
duce two derivatives. To these substances he gave the 
name of diatomic alcohols or g/yco/s, and recognised that 
to eachmonatomicalcohol belonged acorresponding glycol, 
which only differed from it by the addition of an atom of 
oxygen. This new view becamerapidly extended. It wasad- 
mitted that belonging to each glycol there was, or might be, 
a triatomic alcohol or glycerine; that to each glycerine 
there might be a corresponding tetratomic alcohol, and 
so on ; these alcohols only differing from one another by 
the number of atoms of oxygen which they contained, 
the number being always denoted by the atomicity of the 
alcohol. 
Shortly before M. Wurtz’s discovery of glycol, Signor 
Canizzaro, now Professor at the University of Palermo, 
but then Professor at Genoa, had announced the dis- 
covery of a new alcohol, which he called benzylic alcohol, 
having to benzoic acid the same relation as vinous alcohol 
has to acetic acid. He had obtained this substance by 
the action of potash in alcoholic solution, on the essence 
of bitter almonds. 
Some time later the same chemist discovered that this 
alcohol might be equally obtained by means of toluol 
(toluéne). The method he employed was to subject 
chlorinated toluol to the action of acetate of potash ; and 
finally to decompose the acetate of benzyl thus obtained 
by means of potash. 
This benzylic alcohol was the starting point of a new 
series of alcohols known as aromatic monatomic alco- 
hols, and in fact soon afterwards cumylic alcohol was 
obtained, and Signor Canizzaro himself shortly after- 
wards published his discovery of tolylic alcohol. 
It should, however, be observed that the process by 
means of which Signor Canizzaro had obtained his 
benzylic alcohol from toluol, succeeded ill with the homo- 
* © Sur un Glycol Aromatique.” Par M. Edouard Grimaux, 
