Fune 25, 1885] 
NATURE 
185 
Only last November M. Hospitalier brought this subject 
prominently before the International Society of Electricians at 
Paris, and strongly advocated an investigation, so that you shall 
no doubt have their support and concurrence.! 
Examples.—(1) At the very outset students are perplexed by 
such different terms as ‘‘ Ordinary? or Static or Frictional or 
High-tension Electricity.” One author will tell his readers or 
students : ‘‘ For a long time the name Frictional Electricity was 
given to a group of phenomena produced by electrical charges. 
This is an improper expression, because friction is only one 
means for producing electrical charges.”® Another says: 
“Static Electricity is, however, a misnomer: it has no exist- 
ence: all the phenomena are due to static strains, but there is 
always a gradual loss called leakage, which is, however, the 
current due to the actual conductivity of all circuits, and every 
motion set up by so-called static electricity implies a transfer of 
energy and action occurring in a field of force set up in the form 
of strains in the particular inductive circuit in which the motions 
occur.”* A third objects to the word ‘‘ tension” in respect to 
electricity, and points out that ‘all the phenomena observable 
in connection with so-called High-tension Electricity may be 
produced by electricity drawn from batteries or dynamos if the 
electromotive force or difference of potential is sufficiently in- 
creased.” Would not the term ‘‘Electro-statics’” be more 
suitable and comprehensive ? ® 
. (2) The old nomenclature ‘‘ vitreous” and ‘‘resinous,” as 
applied to substances which, when rubbed by certain other sub- 
stances, produce opposite electrical properties, and the scholastic 
one and two fluid theories based upon these effects, should be 
discarded for the more comprehensive modern theory of electric 
polarity of molecules or continuous particles, expressed by 
a ” and ‘‘negative,” or by the algebraical signs (+) 
and (—). 
(3) ‘‘ Electrics,” ‘‘ dielectrics,” ‘‘non-conductors,” ‘‘ insu- 
lators,” and ‘‘isolators”’ are terms used by different writers to 
express a condition or behaviour of certain materials with respect 
to electricity, in contradistinction to the terms ‘‘non-electrics” 
or ‘‘conductors” as applied to other materials. The words 
Ee electrics,” **non-conductors,” and ‘‘ non-electrics ” are, strictly 
speaking, meaningless, because all materials may be termed 
electrics and all conductors, only differing in degree. The 
words ‘‘isolators” and ‘‘isolation” (from the French verb 
zsoler, to isolate or separate) should give way to ‘‘ insulators” 
and ‘‘insulation”” as applied to substances which offer a com- 
paratively greater resistance to electricity than semi or good 
conductors used in connection with the apparatus being referred 
to at the time. 
The term ‘‘ dielectric” ® was first used by Faraday on finding 
that conduction was effected by induction (of polarity from 
molecule to molecule), and is generally employed by practical 
electricians when speaking of the inductive capacity of the insu- 
lating material surrounding the conductor of leading wires or 
submarine cables, or that placed between the plates of a con- 
denser. In this sense, viz., of a body transmitting electric 
induction, or capable of undergoing electric stress, and retaining 
the stressed condition, it is a very appropriate term to use. 
2 ’ 
eS Communication faite A la Société Internationale des Plectriciens, le 
5 Novembre, 1884, par M. E. Hospitalier sur L’Unité de Definitions, Conven- 
es Notations, et Symboles Electriques (vide L’ Electricien, 15 Décembre, 
1884). 
¥ “Sur la proposition du Président, l’assemblée décide qu’une Commission 
spéciale sera nommée  l’effet de rechercher les meilleures méthodes a adopter 
pour les notations électriques et de codifier ces notations. 
M. le Président propose, au nom du Bureau, d’appeler & faire partie de 
la Commission des notations électriquez— 
““MM. Ed. Becquerel MM. H. Becquerel 
E. E. Blavier G. Cabanellas 
Marié-Davy J. Capentier 
Tresca Gauthier-Villars 
Maurice Lévy E. Hospitalier 
G. Lippmann D. Monnier 
Félix Lucas D. Napoli 
Mercadier | Pollard 
De Meritens J. Raynaud 
M. V. Williot. 
“* L’assembleée adopte cette liste a l’unanimité.” 
? The term used by Faraday. (See ‘‘Experimental Researches,” by 
Michael Faraday, p. 82, Art. 264. 
3 “‘Electrician’s Pocket-Book,” by E. Hospitalier, p. 5. 
4 “Electricity,” second edition, by Sprague, p. 6, Art. 20, 
5 ‘Electricity and Magnetism,” by Clerk Maxwell, vol. i., part 1. 
© Faraday’s “Experimental Researches.” p. 364- “T use the word 
dielectric to express that substance through or across which the electric 
forces are acting.” (See also pp. 537, 538-) 
(4) The term ‘‘accumulator” is the name given in several 
text-books to apparatus, such as the Leyden jar or condenser, 
for receiving and retaining quantities of electricity, but has been 
lately inappropriately applied to secondary batteries, which do 
not accumulate electricity. 
(5) ‘‘Cascade,” as applied to Leyden jars, should give way 
to ‘‘ series.” 
(6) ‘*Tension’”’! ‘‘ potential,” and ‘‘electro-motive force,” 
are terms which, when variously and indiscriminately applied, 
have given rise to considerable confusion, and a great deal of 
writing in trying to define them. If we consider ‘‘tension”” as 
simply the stress put upon the current by the electro-motive force, 
and not in the sense that it used to be employed (for example: 
‘Join up a battery or set of condensers for tension”), it might 
do very well if kept in its place ; but it can easily be dispensed 
with.  ‘‘ Potential” is a word that has also given great trouble. 
We find in Sprague’s ‘‘ Electricity ’’? no less than three pages 
devoted to an explanation of the different ways in which the 
words ‘‘ tension” and ‘‘ potential” are employed. Clerk Max- 
well said: ‘‘ The theory of electro-statics is greatly simplified by 
the introduction of this new conception of potential.” ‘* As soon 
as we pass from electro-statics to other departments of electrical 
science, we find that the conception of potential is no longer 
available, except when used in a restricted sense and under care- 
fully-defined conditions.” ‘‘In other parts of electrical science 
we have to deal with electro-motive force in cases where ‘ po- 
tential’ and consequential ‘potential difference’ are words with- 
out meaning.” Prof. Fleeming Jenkin, in his well-known text- 
book on electricity and magnetism, devotes twenty-six pages to 
‘potential,’ and defines ‘‘unit difference of potential or 
electro-motive force in electro-static measure to exist between 
two points when the unit quantity of electricity in passing from 
one to the other will do the unit amount of work.” ‘* The 
property of producing a difference of potential may be 
said to be due to a peculiar force, to which force the name 
electro-motive force is given.” ‘‘ The words electro-motive force 
and difference of potential are used frequently one for the other, 
but they are not, strictly speaking, identical.” ‘‘ Electro-motive 
force is the more general term of the two, and includes differ- 
ence of potential as one of its forms.” ‘‘ Potential” might well 
be reserved for electro-statics, and ‘‘electro-motive force’ for 
electro-kinematics, or current electricity, and thus prevent con- 
fusion. The word ‘‘electric-pressure’’ has come into yogue 
lately, and strongly appeals to those of a mechanical turn of 
mind, seeing that the hydraulic simile of ‘‘ head” or ‘* pressure ” 
is often brought forward to assist in explaining the terms 
‘* potential ” and ‘‘electro-motive force.” 
(7) In magnetism we find the same want of uniformity exists. 
Take the case of a freely-suspended magnetised needle. The 
pole which turns towards the geographical north is variously 
called the ‘‘austral pole,” ‘north pole,” ‘‘ north-seeking pole,” 
marked pole,” and is painted red by Sir Wm. Thomson, while 
Sir Wm. George Airy, Prof. Guthrie, and others paint it blue. 
It is sometimes indicated by French makers by the letter 4, and 
by British by the letter V. The pole which turns towards the geo- 
graphical south is correspondingly called the ‘ boreal pole,” ‘fsouth 
pole,” ‘‘south-seeking pole,” ‘‘non-marked ;”’ painted blue by 
Thomson, and red by Airy, Guthrie, and others, and indicated by 
the letter B. or S. Such is the general doubt and diversity in regard 
tothe nomenclature onthis subject, that eachauthor on magnetism 
considers it necessary to state at the outset which term and symbol 
he intends to apply. If once for all the pole which turns 
towards the north was termed the ‘‘ orth pole,” painted blue, 
and indicated by the letter 2V, and the opposite pole was termed 
the “south pole,” painted red, and indicated by the letter 5S, 
much vexation would be saved. The French terms “‘austral” 
and ‘‘ boreal,” with letters 4 and B, should be obliterated. In 
this way the earth would have a uniformly recognised polarity, 
which would of course be opposite to that of the magnetised 
needle—in other words, the true north pole of the earth would 
be that situated near the geographical south pole.* 
(8) Sailors and some writers on the mariner’s compass call the 
angle which the magnetic meridian makes with the geographical 
meridian the ‘‘ variation” of the compass, while electricians 
1 For a good definition of these terms, see “ Electricity and Magnetism,” 
by Clerk Maxwell, vol. i. p. 49. ? 1884 edition, pp. 58-62. 
3 Sir Wm. Thomson calls the magnetic pole of the earth, situated near. the 
geographical north, the “north pole,” and the end of the magnetised 
needle which points towards it the “ trwe south pole ” of the needle, and 
paints it red 
