114 
NAT ORE 
[ DECEMBER 3, 1903 
The new elements, based on these data, are as follows :— 
Maximum=J.D. 2396 168°738)\ (M.T. Paris) +7°176382 E. | 
Minimum =J.D. 166°365f +0'14 sin (0°-044 E. + 304°) | 
or | 
Gly di Sri5 Gb Ie ok 
Maximum 1848 May 20 17 42 43\ +7 4 13 594 E. 
Minimum ,, ,, 18 8 45 36) +202m,sin (0°*044 E. + 304°) 
and a comparison of the weighted means of his own and 
other observations leads M. Luizet to the conclusion 
that the interval between the principal and secondary 
maxima is 2-373 days, or 2d. 8h. 58m. (Astronomische 
Nachrichten, No: 3911). 
ABSORPTION OF STaR LiGut By CoMET 1903 c.—Prof. Max 
Wolf publishes, in No. 3914 of the Astronomische Nach- 
richten, two photographs of comet 1903 ¢ taken on July 
25 when the comet was passing in front of the 6.5 magni- 
tude star B.D.+63°.1056. On comparing these photo- 
graphs with the observations of comet 1902 III., Prof. 
Wolf arrives at the conclusion that the later comet exhibited 
a selective absorption of star light which was not exhibited 
b» the earlier one. 
PUBLICATIONS OF THE PULKOWA OBSERVATORY.—Vol. x. 
(2nd series) of the Publications de 1’Observatoire Central 
Nicolas, edited by M. M. Nyrén, contains the details of the | 
observations made with the prime-vertical transit instru- | 
ment from 1869 to 1896. In the introduction, M. Nyrén | 
discusses very minutely the errors of the instrument and | 
their corrections, paying particular attention to the causes 
which might produce a small yet persistent residual as yet 
unaccounted for. 
The results were analysed in order to test the validity 
of Chandler’s ‘‘ Ap ’’ term for the variation of latitude, 
and they indicate that that observer’s 
several special methods being named and clearly elucidated. 
Numerous worked examples are given throughout the book, 
each problem and method being clearly illustrated in this 
manner. The work is published by M. A. Hermann, 6 Rue 
‘de la Sorbonne, Paris. 
THE EDISON ACCUMULATOR} 
R. W. HIBBERT read a most interesting paper on the 
Edison accumulator before the Institution of Electrical 
Engineers last week. Since the first announcement of Mr. 
Edison’ s invention nearly three years ago, very little of an 
authoritative nature has been published about the cell; the 
paper which Dr. Kennelly read in May, 1901, showed that 
the invention was full of promise, and further results of 
more extensive experiments and of practical trials have since 
been awaited with eagerness. A description of the cell 
itself was published in Narure in July, 1901 (vol. Ixiv. p. 
241), and as it has undergone little alteration since then 
we need not describe it in detail here; the active materials, 
it will be remembered, are nickel oxide and iron, and the 
electrolyte is a 20 per cent. solution of caustic potash; the 
chemical changes on charge and discharge may be repre- 
sented by the equation 
After charge After discharge 
NiO,| KHOaq |Fe = NiO)KHO.aq |FeO, 
the electrolyte serving merely as an oxygen carrier, and not 
taking any actual part in the final changes of the active 
material, as does the sulphuric acid in the lead-lead-peroxide 
cell. The active materials are packed in perforated steel 
pockets, and the plates, though thin, are rigid and light. 
The construction is thoroughly mechanical throughout, and 
the lightness is obtained without any sacrifice of durability, 
empirical formula requires some slight aE) 
17 
modification, although M. Nyrén_ hesi- 
16 
tates to make a definite statement on 
this point. The constant of aberration 
as deduced from these observations is 
2 
20".4423 if Chandler’s term be con- 
sidered ; without the latter the value is 
kG 
20-4451, and M. Nyrén observes that, 
in the mean, this term seems of small 
8 
importance. 
Volts at cerminals. 
In vol. xiii. of the same Publications 
ay 
a2 & 
M. Nyrén publishes a new catalogue of 
1336 reference stars situated between 
dec. —30° and dec. +90°. This differs oy 
from Struve’s Pulkowa catalogue in os 
only containing stars between magni- 
tudes 5 and 7; at least this was the 
original proposal, but it has been found 
necessary in practice to admit others 
which are just outside these limits. The idea of this selec- | 
tion was to include stars which were faint enough to give 
exact readings, and not too faint to be observed with the 
vertical circle used. Another feature of the catalogue is 
the division of the zone into squares, of which each side 
is 5° in length, and the observation of only one star in 
each zone, thus ensuring the even distribution of the refer- 
ence positions without incurring too great a labour in the 
observations. The section of the zone —15° to +90° was 
observed at Pulkowa, and stars selected from the Bonn 
Durchmusterung were used, whilst the remaining section 
was observed at the subsidiary observatory at Odessa, where 
the Cordoba catalogue was used. Details of each observ- 
ation made are given in the catalogue, and, together with 
the results, they occupy 487 quarto pages. 
GuIDE FOR ASTRONOMICAL AND GEODETICAL CALCULATIONS. 
—Part ii. of Signor J. Boccardi’s ‘* Guide du Calculateur ”’ 
will be found to be an extremely useful reference book by 
all who desire to perform calculations of observational 
results in astronomy or geodesy. It gives lucid explan- 
ations of many typical computations, such as the calcula- 
tion of precessional effects, reductions to apparent place, 
elements of orbits, the determination of an orbit from three 
observations, and the special perturbations of an orbit; it 
also explains and illustrates the method of ‘‘ least squares.’ 
Under the heading of ‘‘ Geodesy ”’ the solutions of many 
typical problems are explained and examples worked out, 
NO. 1779, VOL. 69] 
Fic: 
1.—Discharge Curves of Edison Cell. 
30 
Ampere-hours 
From the Joxrynal of the Institution of Electrical 
Engineers. 
which is one of the chief faults of the lighter types of lead 
cells. The standard size of automobile cell is 13 inches 
high (over all) and 5-1 3-5 inches horizontally. The weight 
is 17-8 lb. The E.M.F. is approximately 1-35 volts, and the 
internal resistance 0-0013 ohm; the output at 60 amperes 
discharge is 210 watt-hours, the ‘capacity working out, there- 
fore, at 11-8 watt-hours per lb. This figure agrees very 
closely with those which were published originally; Dr. 
Kennelly put the output at about 14 watt-hours per lb., and, 
in the article referred to above, we calculated from a dis- 
charge curve which had been published an output of 10 
watt-hours per lb. The lightest lead cells in some instances 
approach, or even exceed, these figures, but on the average 
the result is considerably better than that obtainable in 
practice with lead accumulators. It wiil be seen, however, 
that in many other respects the Edison cell promises to 
prove much superior, especially for motor-car work. 
Mr. Hibbert’s tests were made partly under laboratory 
conditions and partly on the road. The discharge curves 
reproduced in Fig. 1 were taken in the laboratory, and show 
that the Edison cell possesses in a remarkable degree one 
very desirable characteristic, namely, that of giving a good 
output in ampere-hours when discharged at heavy discharge 
rates. Taking the normal discharge current as 30 or 40 
1 ‘The Edison Accumulator for Automobiles.” By W. Hibbert, 
Abstract of paper read before the Institution of Electrical Engineers. 
November 26. 
