
‘ 
Dec. 29, 1870] 

NATURE 
167 

the genus Ceratodus. Is not all this the most palpable evidence 
that there exist in nature types which combine structural features 
that are entirely separate in other types? and it is to such types 
I have applied the name of synthetic types.” 
Lumiere Cendree 
Ir may perhaps be of some interest to you to know that the 
phenomena of ‘‘ Lumiere cendrée ” was distinctly seen in Surrey 
on the evening of the 25th inst., between 4 and 5 p.m. With 
the aid of an opera-glass, I saw clearly the whole of the dark 
portion of the moon’s disc ; and some friends who were with me 
at the time were able to see it with the naked eye. 
H. G, S. Smitu 
Trinity College, Cambridge, Dec. 27 

Measurement of Mass 
| 
WITH reference to the very favourable notice in your last | 
number of my edition of Deschanel’s ‘‘Traité de Physique,” will 
you allow me to remark that my reason for rewriting the section 
on mass (§ 42) was that Deschanel, in accordance with what has 
been till recent years an almost universal custom, employs a 
variable unit of force, and, as depending upon this, a variable 
unit of mass, so that the number denoting the mass of one and 
the same body is diminished as the body is carried from the 
equator to the poles, and would increase up to infinity if the body 
fell to the centre of the earth. 
The reviewer says, ‘‘the conception of mass is always a diffi- 
cult ore for a beginner.” ‘This is doubtless true when the con- 
ception is hampered with the inconsistencies arising from this 
vicious system of measurement ; but I do not think the concep- 
tion of a found or gramme of matter presents much difficulty, and 
these are the units in which, according to the best modern usage, 
I have indicated that mass is to be expressed. 
As regards the coefficient of absorption of ammonia, the re- 
viewer is right. A mistake was committed in extracting the 
number from a table, of which, if I may judge by his initials, the 
reviewer is the author. In future, I would entreat him to 
make his tables more easy of reference. J. D. EVERETT 
Belfast, December 26 
Hailstones 
In Nature of the 15th there is an account of hailstones of a 
form deviating considerably from the spherical. Hailstones are 
frozen raindrops, and a rain-drop falling through a vacuum 
would of necessity be spherical, but in falling through the air it 
must tend to assume the form of least resistance, whatever that 
may be. I was told many years ago of hailstones which had 
been picked up and found to be of the form of Minié bullets. 
I do not vouch for the truth of this, but I think it likely; the 
Minié bullet was, I believe, the nearest approach to the form of 
least resistance that the inventor was able to arrive at. 
JosepH JOHN MURPHY 
Old Forge, Dunmurry, Co. Antrim, Dec. 20 
Darlingtonia Californica 
Mr. Ropinson’s suggestion, reported at page 159, as to the 
cultivation of this plant in England, has been anticipated by 
Messrs. Veitch and Sons, who have grown the plant for a con- 
siderable time in their houses at Chelsea. 
In London, as in California, this curious plant possesses the 
same irresistible attraction to insects, and as I have repeatedly 
examined living plants at Chelsea, perhaps the following notes 
taken in connection with those printed in your last number may 
have some interest. 
This so-called ‘‘ pitcher plant,” when fully grown, resembles 
in shape the upraised head and body of an excited cobra, with 
hood expanded and prepared for a spring; the head is at right 
angles with the hollow vertical body, and apparently presents no 
opening by which an insect could enter ; under the place where 
the lower jaw would be, hang two large reddish appendages like 
the ‘‘wattles” of a fowl. At Chelsea this plant possesses such 
an extraordinary attraction for flies (principally blue-bottles), that 
the hollow “pitchers” are generally full of their dead bodies ; 
what this attraction is I am unable to say, as the plant is scent- 
less, 
| name forthe Milky Way. 

Last year I had a Darlingtonia before me for some three or 
four hours, whilst sketching it, and I then observed that the 
blow-flies made straight for itimmediately they entered the room. 
| Insects alight on the red ‘‘ wattles ” and then fly upwards into 
the (previously unseen) red-lipped entrance to the tube ; owing 
to the sudden twist in the neck of the pitcher, they are at once 
compelled to descend the hollow body, and, as far as I have 
observed, they never return alive. They keep up a buzzing 
noise for half an hour or so, and then apparently die. 
The old ‘ pitchers” are generally full of dead flies, &c., and 
the lowermost insects, in rotting, cause the ‘‘ pitchers’ to decay 
and split, the flies within being then displayed. These deacl 
flies often drop out through the fissures and become grouped 
round the bottom of the plant. 
os WORTHINGTON G, SMITH 

Aurora Arcs in the East 
I AM inclined to agree with Dr. Burder as to the invisibility of 
Auroras by daylight, yet I can confidently assure him that I have 
many times seen the arch ‘‘almost due east,” that is when the 
extremities point N.N.W. and S.S.E. When such a pheno- 
menon occurred in Newfoundland, some of the old weather- 
wise settlers would tell me to expect falling weather (snow or 
rain) on the following day, as the Northern Lights were in the 
south. But I am sorry to say that I did not note how often the 
Aurora appeared as above, but I dd note that snow fell on 
seventy-eight consecutive days in the autumn of 1867 and com- 
mencement of the winter of 1868. HEnry REEKS 
The Milky Way 
In the number of Narure for November 17, Mr. John 
Jeremiah states that ‘‘ Heol y Gwynt” is the only proper Welsh 
Such is far from being the case. I 
am acquainted with no less than wize other names, equally 
proper for that luminous appearance, such as y //zybr laethog, 
y ffordd laeth, llwybr y gwynt, galaeth, eirianrod, crygeidwen, 
caer Gwydion, llwybr Olwen, and lwybr y mab afradlawn. Of 
these names, y //uybr Uaethog and y ffordd laeth answer precisely 
to Milky Way ; //wybr y gwynt (common enough in Carmarthen- 
shire) is synonymous with feol y gwynt; galaeth (from laeth, 
milk) corresponds with galaxy ; eirianrod signifies a bright 
circle ; and crygeidwen a white cluster. To caer Gwydion (the 
mural enclosure of Gwydion) belongs a tale, which may be com- 
pared with the stories of classical antiquity on the same subject. 
Gwydion is a noted character in early Welsh romance, in which 
he figures as an astronomer andan enchanter. He was the son 
of Don, king of Llychlyn or Scandinavia, and is said to have 
lived in the fourth century. According to the Welsh poets, he 
travelled through the heavens in search of a lady, who had 
eloped with Gronwy Befr, and left a track behind him, which 
has ever since been called Caer Gwydion. When he found the 
faithless lady he changed her into anowl. His scientific acquire- 
ments are often mentioned in Welsh mythology, and frequent 
allusions are made to him as an enchanter by the early bards. 
He is said to have been instructed in magical arts by Math ab 
Mathonwy, and in the Mabinogi, or tale which bears the name 
of the latter, his achievements are detailed at length. According 
to some of the Welsh records he was buried at Morfa Dinlle, 
on the seashore near Carnarvon. 
Gwydion is not the only one of the family of Don whose name 
is associated with astronomy. Don himself gave his name to 
the constellation of Cassiopeia, which is called in Welsh Zlys 
Don, the Court of Don ; and Caer Arianrod, the Corona Borealis 
or Northern Crown, is so called after his daughter Arianrod. 
Lhwybr Olwen (the path or course of Olwen) refers to another 
distinguished character in Welsh mythology. Olwen was the 
daughter of Ysbyddaden Bencawr, a prince of the Northern 
Britons, who lived in the sixth century. Her extreme beauty 
was proverbial, and her charms are frequently alluded to by the 
ancient bards. It is stated of her that four white trefoils sprang 
up wherever she trod, and from this circumstance she was called 
Olwen, or white track. She was sought in marriage by Cilhwch, 
prince of Clyddon, and his adventures in order to obtain her 
form the subject of the Mabinogi of Cilhwch and Olwen, which 
will be found printed, with an English translation, in Lady 
Charlotte Guest’s ‘‘ Mabinogion,” ii. 197,249 
What connection the other name, //wyér y mab afradlawn 
(the path_or course of the prodigal son), may haye with the 
