198 
NATURE 
[ Dec. 29, 1881 
astronomical and geographical knowledge is but of recent date, 
and, as already stated, Dante formed many of his cosmographic 
conceptions chiefly from hearsay. N. PERINI 
ss 
The Horse-Power given to any Part of a Circuit by 
Intermittent Light 
Some time ag», with Prof. Ayrton, I designed and constructed 
an instrument t» measure the horse-power given electrically to 
any incandescent or arc lamp, or to any part of a circuit, an 
improvement 0. the instrument previously devised by M. Deprez ; 
the pointer of a suspendcd coil moves at once to a mark on a 
scale which tells the horse-power, The instrument is dead beat, 
and, what is very important, by a special commutator arrange- 
ment it can be calibrated with much smaller forces than it is 
intended to measure. The current in the suspended coil is pro- 
portional to the difference of potential at the ends of a part 
of the circuit, and the fixed current which causes its deflection is 
the total main current in the circuit, so that the deflection repre- 
sents the product of these two factors. The instrument was 
deserib:d at the Society of Arts in March last, and was exhibited 
at the British Association meeting at York. It will, however, 
necessarily only work accurately with non-reversed currents 
because of the self-induction of the suspended coil of fine wire, 
and it is very important to be able to make the same measure- 
ment for reversed currents, 
At the Electrical Congress at Paris, soon after the reading of 
M. Joubert’s paper, in which he showed how to measure the 
mean value of the square of the difference of potential at two 
ends of a part of a circuit in which reversed currents are flowing, 
Prof. Ayrton described to me a method of performing the mea- 
surement of the horse-power for reversed currents which seemed 
to have suggested itself to him and to Prof. Fitzgerald of Dublin 
simultaneously when hearing M. Joubert’s paper. It was this : 
Let there be three points in the circuit at potentials 4, VY, V3, 
at any instant, and let there be a known resistance (wiih no 
self-induction) between VY, and V,. Let V3 be coanccted with 
the needle of a Thomson’s electrometer, and let /; and V, be 
connected with the quadrants, | being also connected with the 
outside of the Leyden jar: then the deflection of the needle 
measures the mean value of 
(e- Vy) (% - “thy, 
Now let the needle and a pair of quadrants be connected with 
V,, the other pair with 14, and we measure the mean value of 
the square of (/,—V,). The difference of these measurements 
is easily seen to be A times the expeaded energy which we 
want to know. 
I was not present when Professors Ayrton and Fitzgerald 
communicated their idea to one another, but immediately after- 
wards Prof. Ayrton explained it to Sir William Thomson and 
to me together, makiny sketches of the necessary connections. 
Sir William thought well of it, but feared that perhaps the 
present quadrant electrometer would not be sensitive enough for 
the measurements. We suggested, however, the use of our 
multireflex arranzement (see La Lumiére Electrigue, October 5, 
1881) for creating greater sensitiveness, and as he was pleased 
with the idea, we have, sivce that tine, in our very short inter- 
vals of leisure, been trying t» arrange an electrometer which 
shall be sensitive enough fur the purpose. 
I observed to-day that M. Potier in the October nuwnber of 
the Fournal de Physigue publishes the same idea, and I wi-h 
to place it on record that the fundamental idea of the new 
process, which seems to me very feasible and of considerable 
practical importance, oceurred to Messrs, Ayrton, Fitzzerald, 
and Potier independently. JoHN PERRY 
Talgarth Road, West Kensington, 1ecem'er 6 
The New Red Star in Cygnus 
THE above star, which I found on the 22nd of May last, and 
which then appeared of the 9th magnitude, and reached § m. on 
June 8, seems now no more than 12m. Estimations of very 
small magnitudes are, of course, very difficult, but I believe I 
am not under the mark in saying 12 m., as I found the star not 
easy with a 44 inch O.G. At the same time its deep crimson 
seemed very striking by glimpses, and in its present state it is, 
perhaps, the smallest amonz the stars whose red colour has been 
observed. It will probably have to be classed among the most 
remarkable variables. J. BIRMINGHAM 
Meteor 
TAKING a look at the eclipse of the moon oa December 5, 
about 5.44 p.m., I happened to see a meteor that is, I think, 
very noteworthy, thouzh, perhaps from distance, its apparent 
size was so small that I might have scarcely seen it but for the 
temporary lessening of the light of the moon, Its motion was, 
throughout its visible course, horizontal and slow. When it 
met my eyes, it was just below the Pleiades. I followed its 
flight to the northern end of the eastern sky ; there it seemed 
to go on out of my sight, without fall or collapse: for aught I 
know, I might have observed it even from the extreme south, had 
my eyes been turned thither at the outset ; I would draw attention 
to this fact, as well as to its horizontal motion and its seemingly 
slow progress. The grandeur of the glories displayed_by that 
night’s clear sky was at its height as this mysterious stranger 
passed above our winsome satellite—ihen a thing of ‘‘eerie 
beauty,” its glistening golden ring half-clasping, like ‘the old _ 
moon in the new moon’s arms,” the earth-shadowed orb over it, 
and the latter shimmering with the maroon ember-like sheen 
called by the French /a /umiétre cendrée. 
Joun HoskyNns-ABRAHALL 
Combe Vicarage, near Woodstock, December 16 
SEA-SICKNESS.—-This must be declined as a subject for 
correspondence, 
A NEW ELECTRICAL STORAGE BATTERY‘ 
“I“HE great utility of some thoroughly practical method 
of conserving electric force has caused a great deal 
of attention to be applied to the subject ; no system of 
electric supply can be considered as perfect until some 
means is used to so store the force generated that it may 
be drawn off equally and regularly, and this whether the 
generator be on or off. If we take, as an example of 
electric supply, the present systems of electric lighting, it 
is at once seen, should an accident or stoppage take place 
in the machinery generating the current, the whole of the 
apparatus such as lamps or motor-machines are influ- 
enced ; should there be a reservoir of electricity between 
the generator and the apparatus of whatever sort for 
utilising the force this inconvenience would not occur. 
All the present systems of storing electricity depend on 
certain chemical changes produced by electrolysis. 
I have gone through a long series of experiments on 
storing electricity and made many forms of cells, one 
being a porous pot containing dilute hydric sulphate and 
a sheet of lead, in an outer vessel containing a sheet of 
lead in solution of acetate of lead, the plate in the porous 
pot being made the positive electrode ; this cell had the 
power of storing electricity, by peroxidising the positive 
electrode, and depositing from the acetate of lead solution 
metallic lead on the negative electrode, the hydrogen 
having combined to form acetic acid. On discharging 
the peroxide is reduced, and the oxide formed during 
discharge on the other plate dissolves in the acetic acid, 
forming the original solution of acetate of lead; by this 
means I eliminated the injurious effects of the hydrogen 
on charging. 
During my experiments I found that red oxide of lead 
is a very bad conductor of electricity, and the peroxide 
a good conductor. I also discovered that by amalga- 
mating lead plates with mercury a marked increase was 
* “On a New Electrical Storage Battery."’ By Henry Sutton (Ballarat 
V.ctoria). Communicated to the Royal Society by the President. 
