} 
May 4, 1871] 
NATURE 7 

work. If the above names be adopted, they give us at once the 
foot-kinit as the unit of work based on the pound, foot, and 
second, the foot-pound (which varies with the value of g) being 
equal to ¢ foot-kinits. 
In like manner we have, for the metrical system, the metre-dyne 
and its derivatives. 
But it would, I think, be advantageous to have short and in- 
dependent names for these units. For, in the first place, we are 
thus saved from such cumbrous names as metre-kilodyne and 
metre-megadyne, which would be necessary in expressing large 
quantities of work ; in the second place, energy of motion de- 
pends directly upon mass and velocity, and is only indirectly 
connected with the unit of force; and, in the third place, the 
_ characteristics of energy are such as specially entitle it to names 
suggestive of simplicity rather than of compositeness. 
I propose, therefore, to call the foot-kinit, whether of work or 
energy, the exe. A thousand ergs to make one £z/erg, which will 
be about 31 terrestrial foot-pounds, and a million ergs to make 
one Zollexg, which is a little less than the work done by one 
horse-power in a minute. 
The kinitic energy of » pounds, moving with a velocity of 7 
feet per second, is + mv? when expressed in ergs. 
The energy value of a Fahrenheit unit of heat is 772 x 32°194 
= 24,854 ergs. 
In the metrical system, let the metre-dyne of work or energy 
be called the ove (from dvos). A thousand pones to make one 
hilopone, which is the work done by a &ilodyne working through 
a metre, or by a dyne working through a £:/ometre, and is about 
Bar of the variable unit of work in common use among French 
engineers, called the kilogrammetre. A million pones to make 
one megapone, which is about 723 terrestrial foot-pounds. 
In employing the prefix mega to denote a million, I have 
followed the excellent example set by the B. A. Committee on 
Electrical Standards. As megerg would be intolerable, and 
megalerg sounds like a confusion of genders, I have substituted 
pollerg. 
In constructing a new nomenclature, the metrical system is 
entitled to the best names which can be found, but the pound 
and foot cannot be ignored. J. D, EvERETT 
Rushmere, Malone Road, Belfast 
The Name “ Britain” 
In his remarks on the derivation of the name ‘‘ Britain,” 
“A. R. H.” says that tin ‘‘is found only in one of the Britan- 
mias.” This is incorrect, for tin occurs in Brittany, and also in 
Gallicia. The fact of the three Britains mentioned by ‘‘ A. R. H.” 
being all tin-bearing districts seems to confirm the derivation 
given by Mr. Edmonds in NATuRE for February 16. 
: Gal INa EB: 

Piedimulera, Val d’Ossola, Piedmont, April 25 

Derivation of the Word “ Britannia” 
Ir Mr. Edmonds considers himself right in his derivation of 
¢ Britannia” and ‘‘tin,” he will have to explain on the same 
basis the conformable names, and this he will find difficult to do. 
The name B-ritannia corresponds with S-ardinia, D-ardania, 
and possibly with Mauritania, and these again with a number of 
river names of the root RDN (=RND, BRN, &c.), such as Rotanus, 
Rhodanus, Drinus, Eridanus, Artanus, Triton, Orethus, &c. 
B-radanus, P-rytanis, P-arthenias, V-artanus, are examples of B. 
K-artenus, I-ordanes, I-ardanes, I-ardenus. Then there are 
examples of Aternus, &c., Tanarus, &c., Mzeander, &c., Orontes, 
&c. These must all be explained on one principle. 
In the same way as Britannia is allied to river names, so are 
many of the ancient (classic) names of countries (except such as 
are volcanic) allied to river names of various roots, as RBD, &c., 
RKN, &c., SBN, &c. 
These names are not explainable in Phcenician, because they 
were given long before the Phcenicians entered on the stage of 
history. They are Paleogeorgian, in a language to which 
Georgian, Lesghian, and other Caucasian languages are allied. 
These names were given by the Caucaso- Tibetans, 
This is explained in my paper lately read before the Anthropo- 
logical Institute and recorded in NATURE, and the name of 
Britannia is illustrated in papers sent in to the Society of Anti- 
-quaries and the Royal Irish Academy. 
32, St. George’s Square Hypr CLARKE 


Aurora by Daylight 
TuHaT the Aurora Borealis has been seen by daylight has 
never been doubted by me, although till now I have not been 
able to collect sufficient evidence to induce others to believe in 
the possibility of it. Your correspondent Mr. John Langton, in 
your last issue, gives two instances of the aurora having been 
seen during day time, which, I think, ought to dispel all further 
doubt. However, to satisfy the most sceptical of your readers, 
the following few cases have occurred to me :— 
‘A.D, 1122, . . . . « ~ This same year died Ralph, 
Archbishop of Canterbury ; that was on the 13th of the kalends 
of November (October 20). After this were many shipmen at 
sea and on the water, and they said that they saw on the north- 
east along the earth a great and broad fire, and it increased 
speedily upwards in extent towards the sky, and the sky opened 
itself in four parts and fought there against it as if it would ex- 
tinguish it; but nevertheless the fire extended up to heaven. 
They saw that fire in the dawn of the day, and it continued until 
it was quite light. This was on the 7th of the ides of December 
(December 7).”— Axglo-Saxon Chronicle. 
It may seem bold to advance this as the record of an auroral 
appearance, but not to those who have studied this and other 
chronicles with their wearying vaguenesses. This passage gains 
clearness by the following lines from the ‘‘ Prose Edda,” con- 
cerning ‘* The Twilight of the Gods and the Conflagration of the 
Universe,” which I have elsewhere* supposed to be a description 
of the aurora borealis :— 
“«The fire-reek rageth 
Around Time’s nurse, 
And flickering flames 
With heaven itself playeth.” 
In the ‘‘ Second Continuation of the History of Croyland,” 
there is the following curious passage, under A.D. 1467 :— 
CMa eOeeEN; 6 Me NG a o eoeb horsemen and men 
in armour were seen rushing through the air; so much so, that 
St. George himself, conspicuous with the red cross, his usual 
ensign, and attended by a vast body of armed men, appeared 
visibly in great numbers. To show that we ought not to refuse 
our belief to what has been just mentioned, those persons to 
whom revelations of this nature were made were subjected to the 
most strict examination before the venerable Father Thomas, the 
Lord Archbishop of Canterbury.” 
I understand this occurrence to have taken place in the day 
between the rising and setting of the sun, because this passage is 
only part of a longer account of remarkable events which were 
said to have been observed in ‘‘one day.” I do not put this 
instance forward as one of very great value, as the Chronic’e 
of Ingulf is undoubtedly spurious, as shown by Dr. Hickes and 
Sir Francis Palgrave, but the continuation, I think, can be safely 
said to date about the end of the 15th or the beginning of the 
16th century, which, if correct, will place the phenomenon above 
referred to amongst the earliest notices of daylight Auroras in 
English History, and will come next to that mentioned in the 
Anglo-Saxon Chronicle. Of course I only speak here of my own 
acquaintance with the Chronicles, there may be other records, 
but I have not had the opportunity of searching through every 
monastic production. 
Leaving this field of speculation, I come next to a more reliable 
record. | give the whole ot the passage, as it is not very long :— 
** Aurora Borealis, seen in the Day-time at Canonmills.” ‘* Tle 
morning of Sunday, September 9, was rainy, with a light gale 
from the N.E. Before mid-day the wind began to veer to the 
west, and the clouds in the north-western horizon cleared away : 
the blue sky in that quarter assumed the form of a segment of 
a very large circle, with a well-defined line, the line above con- 
tinuing dense, and covering the rest of the heavens. The centre 
of the azure arch gradually inclined to the north, and reached an 
elevation of 20°. Ina short time, very thin fleecy clouds began 
to rise from the horizon within the blue arch ; and through these 
very faint perpendicular streaks of a sort of milky light could be 
perceived shooting ; the eye being thus guided, could likewise 
detect the same pale streaks passing over the intense azure arch, 
but they were extremely slight and evanescent. Between nire 
and ten in the evening of the same day, the aurora borealis was 
very brilliant, so that there is no reason to doubt that the azure 
* Vide NATURE, vol. ili. p. 175. 
+ For a similar case to this see note to my letter on the aurora borealis in 
NATUuRE, Vol. iii., p. 487, 
