186 
call it the ‘‘declination.” Variation is, properly speaking, the 
hourly, diurnal, annual or secular changes which occur in the 
value of the elements of terrestrial magnetism. This leads to 
great confusion and argument between the electricians and the 
officers of a telegraph steamer. The declination for each place 
is marked on the Admiralty charts. Sailors also speak of the 
‘*deviation ”’ of a compass, meaning by that the local error due 
to the resultant of the quadrantal, semicircular, and heeling errors, 
&c. It would be far betterifthey simply spoke of the ‘* compass 
error,’ or angle which the meridian of their compass-needle 
makes with the true north and south magnetic bearings. This 
deviation or compass error arises from local magnetic influences. 
Sir William Thomson’s well-known compass, when properly 
adjusted on board a ship, has no compass error, and therefore 
the only thing to guard against and correct for in the steering of 
a ship Is the declination of the place where the ship may be at 
the time of observation. Of course, if the magnetism of the 
ship changes in the slightest, due to a change of cargo or posi- 
tion thereof (if of iron or steel), or due to buffeting the waves 
for some time on one course, a slight error will creep in, but the 
compass can be soon adjusted to the new condition of affairs, 
and the officers have therefore seldom to think of or even speak 
of “ deviation ” or ‘* compass error.” 
(9) When we come to electricity generated by batteries, we 
find the expressions ‘‘ galvanism,” ‘‘ voltaic electricity,” ‘‘ dy- 
namic electricity,” ‘‘ electro-kinetics,” ‘‘ current electricity,” ? 
&c., according to the fancy of the writer or speaker. Surely one 
name might suffice ; and certainly the older term ‘“‘ galvanism,”’ 
and ‘‘ voltaic electricity’ might well be left to the past. The 
simple term ‘‘current electricity” seems to commend itself, as 
most of the effects in connectlon with this branch of the subject 
have reference to electricity as if it was in motion or distributing 
itself over a conductor. 
*-(10) *‘ Density fof current” and ‘‘ intensity of current” often 
cause great confusion. ‘Density of current’? should only be 
used in the case of electrolysis or electro-deposition of metals. 
Here it means the amperes per unit of surface of the cathoder. In 
electro-statics ‘‘ surface density ” or ‘‘ electric density ” means the 
quantity per unit area of surface. ‘‘ Intensity” was used at one time 
in the same sense as ‘‘ electro-motive force ” is now, and therefore 
not so much out of place there ; but several writers, notably Prof. 
Silvanus Thompson, have thought fit to borrow the French term 
“Intensité de courant” wholesale, instead of a translation 
thereof, and to symbolise it by the letter 7, The literal transla- 
tion of the French word zn¢enszté being strength or amount, 
therefore the expression ‘‘ current strength,” or simply ‘‘ cur- 
rent,’ symbolised by C, is far preferable, for it conveys the 
correct meaning of the quantity in a given time. With a little 
pressure, French electricians would no doubt agree to the symbol 
C instead of Z, to promote uniformity. Then 7 might be reserved 
for intensity of magnetism, where it suits very well. 
11. ‘Positive electrode,” ‘‘(+) terminal,” ‘‘zincode,” 
“anode,” ‘‘positive pole,” and ‘‘negative plate,” severally 
used by different writers to designate that end of a cell, battery, 
or pile where the current leaves, and ‘‘negative electrode,” 
“*(—) terminal,” ‘‘platinode,” ‘‘kathode” or ‘ cathode,” 
“negative pole,” ‘‘chlorous pole,” ‘‘ positive plate,” where 
the current returns to or enters the same, requires revising and 
simplifying, more especially when we consider that the end 
plates of a battery are of opposite sign to their electrodes or 
terminals, and that the nomenclature is still further complicated 
when we come to consider secondary batteries or electrolysis by 
the terms anion,” ‘‘kation” or ‘‘cation,” and ‘‘ions.” Take, 
for example, the definition given by Sprague? of ‘‘anode” : 
“The positive electrode or pole of a baitery ; the wire or plate 
connected to the copper or other negative element of the battery ; 
the plate which leads the + current into a solution to be decom- 
posed, and at which are set free the oxygen, acid radicals and all 
—ions (anions). In electro-metallurgy it is usually formed of 
the metal to be deposited, in which case it is called the soluble 
anode or pole” !! 
* See Ferguson’s ‘‘Electricity,” second edition, by Prof. Blyth, p. 164. 
The term “ electro-kinematics” has been used by Clerk Maxwell to cover a 
large part of this subject, such as ‘‘electric current,” ‘‘ conduction,” “ re- 
sistance,” ‘‘electro-motive force,” “‘ electrolysis,” &c. (See ‘‘ Electricity and 
Magnetism,” by Clerk Maxwell, vol. i. part 2.) 
2 Sprague’s ‘‘ Electricity,” 1884 edition, p. 624. 
3 See Faraday’s ‘‘ Experimental Researches,” articles 661 to 667, on De/t- 
nitions of New Terms, where he very clearly points out the meaning he 
a:taches to the words ‘‘electrode,” ‘“‘anode,” ‘‘ cathode,” “ions,” ‘‘anion,” 
“cation,” &c. 
NATURE 
[Fune 25, 1885 
12. Again, we have the two different ways of graphically 
representing a battery 
ere Pep me ee 
fl + | 
according to the whim or fancy of the writer. Practical sub- 
marine electricians were the first to use this very neat and handy 
way of representing a battery and its poles, and always adopted 
the former method, with the long thin vertical line for the plate 
where the current leaves, and the thick short line for the plate 
where the current returns to the battery. Why should this have 
been departed from? It is a mere arbitrary arrangement, but, 
being a most convenient symbol, it should be used in a uniform 
manner. Mr. John Munro proposes that the symbol for a 
secondary battery should be a modification ef this, viz., 
Li b— 
+ 
pe le 
the current outside the cell proceeding from the long line to the 
short one. 
13. °‘ Parallel circuit, multiple arc,” ‘‘loop circuit,” ‘in 
loop,” ‘‘ derived circuit,” ‘‘shunt circuit,” are all expressions 
to signify pretty much the same thing, where one expression, 
‘shunt circuit,” would do. 
14. ‘‘ Polarisation” is a term used in many different senses— 
for example, the polarisation of battery plates, molecular 
polarisation due to electrification sr magnetisation, polarisation 
of light due to magnetism, &c., as in Dr. Kerr's experiments. 
Some reform is required here. 
15. Coming to telegraphy, telephony, and electric lighting, 
we find, as M. Hospitalier points out, ‘‘the words ‘ generator,’ 
‘receiver,’ ‘transmitter,’ and ‘motor’ are mixed up by different 
inventors, sometimes through ignorance, sometimes willingly.” 
“‘A ‘generator’ is an apparatus which, receiving energy of a 
certain nature, produces an energy of another nature, and it 
borrows its name from the nature of the energy which it gene- 
rates. A ‘receiver’ is an apparatus analogous to the generator, 
but it borrows its name from the energy which it receives.” ‘*A 
given apparatus is at once a generator and receiver—for example, 
an electric motor is a generator of mechanical energy and a 
receiver of electrical energy.” ‘‘ The name ‘transmitter’ ought to 
be reserved for an apparatus which, receiving an energy of a 
certain kind, produces or brings into play an energy of the same 
kind or of the same form.’’ For example, a relay on a telegraph 
system, or induction coils as used on a trunk telephone line with 
several subscribers’ Jines at each end, or in electric lighting on 
the Gaulard and Gibbs’ system, lately tried in London. Pro- 
fessor Silvanus Thompson uses the phrase ‘‘ Dynamo-electric 
machinery ” in the most general etymological sense of the term, 
as meaning machinery for converting the energy of mechanical 
motion into the energy of electric currents, or vice versa, except- 
ing such induction machines as Holtz, Voss, &c. He thinks 
this reduces the ambiguity to a minimum, and leaves the word 
‘*motor” to be applied, if desired, to the steam-engine, water 
wheel, &c., from which the mechanical motion is derived. The 
terms ‘‘magneto-clectric machine,” as applied to a dynamo 
fitted with permanent field-magnets, and “electro-magnetic 
machine” to a series, separately-excited, shunt, or compound- 
wound dynamo (generator or receiver) are very handy expres- 
sions, and should not be discarded. 
16. We have dealt hitherto chiefly with definitions and no- 
menclature, and have given a few examples: others will occur 
to every member present. We now come to abbreviations and 
notation with symbols. The want of uniformity here, and the 
need for systematising, is still more obvious, but perhaps more 
difficult to accomplish. Every one admits the great advantage 
in being able to write down the symbols for chemical elements 
and their actions and reactions one with the other in the form of 
simple equations, which any one may comprehend who knows 
the subject, without a detailed description of what each letter or 
symbol stands for. Electricians should not rest satisfied until 
they are supplied with a similar universally-accepted notation, 
whereby electrical phenomena and actions may be similarly 
treated. The author submits a sample of what he considers 
would be useful in this respect. Many of them are taken from 
Munro and Jamieson’s ‘‘ Pocket-book of Electrical Formule,” 
where an effort was made to use the same notation and abbre- 
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