APRIL 30, 1914]| 
of the circuits in cases of accidental short circuits 
with the view of localising the damage that can be done. 
For example, it is possible by placing reactances in 
the conductors between the generators and the switch- 
board, to limit the current under conditions of short 
circuit on the switchboard or feeders to, say eight 
times, the normal working current, and thus to protect 
the machines from enormously greater rushes of cur- 
rent that would be destructive. The paper discusses 
the relative utility of such reactances in the generator 
leads, in the feeders, and between different sections 
of the main ‘“‘bus-bars,” and suggests various com- 
bined arrangements. These reactances generally take 
the form of large coils without iron in their magnetic 
circuit, but a partial iron circuit is sometimes em- 
ployed. An appendix discusses the effect of bus-bar 
reactance on tke parallel operation of alternators. 
In twelve pages oi the March number of the Journal 
of the Franklin Institute Mr. W. P. Davey, of the 
X-ray laboratory, Cornell University, succeeds in 
giving a most valuable summary of the present state 
of our knowledge of R6ntgen, or X-rays. After 
explaining the production of Réntgen rays by the 
impact of kathode rays on the target of a vacuum 
tube, he shows that they produce fluorescence in 
certain bodies on which they impinge, they affect 
photographic plates and ionise the air through which 
they pass. In each case the laws which have been 
found to hold are stated. When the rays fall on metals 
or on metallic salts they produce in certain cases 
secondary radiations which differ in properties from 
the original rays, and by analogy have been called 
fluorescent Réntgen or X-radiations. The methods 
adopted for the measurement of the quality or pene- 
trating power of the radiations, and the quantity of 
radiation which falls on a given surface in a given 
time, are also described. The article will prove of 
great value tc those who wish to make themselves 
acquainted with the principal facts of the subject 
without entering into details. 
THE Société de Chimie-Physique has issued two 
more numbers of its series of monographs. These 
are vii., ‘‘Paramagnetism Applied to the Study of 
Metallic Salts,’ by Mile. E. Feytis; viii., ‘‘ Relations 
between Chemical Constitution and the Coloration of 
Organic Substances,” by M. André Meyer. The latter 
contains, in addition to a review of the chief types of 
coloured compounds, a bibliography of the subject 
extending over ten pages, and containing more than 
two hundred references to original papers. 
AN interesting illustrated article on charcoal burn- 
ing in the Weald, by Mr. W. R. Butterfield, is con- 
tained in the April number of the Selborne Magazine. 
This primitive industry is still carried.on in the 
Weald, although it has declined considerably during 
the last thirty years, owing to the decreased quantity 
of home-grown hops, for the drying of which the 
charcoal is mainly used. All the charcoal that is re- 
quired is made during the few weeks before hop- 
picking, and the ‘‘collier,’’ as the burner is called, 
and his mate move from farm to farm as required, 
and cover a wide area each season. The burners 
NO. 2222, VOL. 93] 
NATURE 223 
depend wholly upon empirical knowledge, either 
acquired by their own experience or handed on to 
them by their predecessors, and the operation is one 
requiring considerable skill and unremitting vigilance 
day and night. 
THERE is an interesting illustrated article in the 
Engineering Magazine for April, giving an account 
of the workshops and methods of the Ford Motor 
Company. This company turns out 1000 automobiles 
a day at its Highland Park Works in Detroit. The 
other two factories belonging to the company, one at 
Ford, Ontario, Canada, and one at Manchester, Eng- 
land, bring the total Ford car-producing capacity to 
at least 1200 cars a day. The company produces one 
article only, viz., the Ford motor-car, and employs 
rather more than 15,000 hands. 
OUR ASTRONOMICAL COLUMN. 
ASTRONOMICAL OCCURRENCES FOR May :— 
May 1. ith. 24m. Neptune in conjunction with the 
Moon (Neptune 4° 17’ S.). 
» 20h. 43m. Mars in conjunction with the 
Moon (Mars 1° 37’ S.). 
15. 7h. 4m. Uranus in conjunction with the 
Moon (Uranus 2° 3' N.). 
16. th. som. Jupiter in conjunction with the 
Moon (Jupiter 1° 13’ N.). 
», 2h. 7m. Venus in conjunction with Saturn 
(Venus 2° to’ N.). 
», 20h. om. Uranus stationary. 
»» 23h. om. Mercury in superior conjunction 
with the Sun. 
25. 23h. 5m. Saturn in conjunction with the 
Moon (Saturn 6° 9’ S.). 
26. 2th. 2m. Venus in conjunction with the 
Moon (Venus 3° 21’ S.). 
28. 17h. 57m. Neptune in conjunction with the 
Moon (Neptune 4° 1’ S.). 
16m. Mars in conjunction with 
Moon (Mars 0° 42’ S.). 
»» oh. om. Mercury at greatest heliocentric 
latitude N. 
CoMET 1914A (KRITZINGER).—Recent observed posi- 
tions of comet 1914a (Kritzinger) have enabled Prof. 
Kobold (Astronomische Nachrichten, No. 4729) to im- 
prove the elements of this comet, and consequently 
the ephemeris. The new positions for the current 
week are now as follows :— 
12h. Berlin M.T. 
30, “shi the 
R.A. Decl. Mag. 
eh ie OS P % 
April 30 18 13 21 +26 30-7) (12.9 18:6 
May I TES. Vote. 17 31-9 - 
2 PO BA i ate 18 32:8 
3 27 14 se 1Q 33°3 
4 OSS pes © 29) 3355 
5 GOEAGer ss 21, 3226 
faye Bar JIT PBS (aad | | GN Gey 
2 tats Pt ES AG '9 te 23) 20:0) ines 838 
The comet is situated in that portion of the con- 
stellation of Hercules lying to the south of Vega, and 
it will be noticed that the present calculation makes 
the object brighter by more than half a magnitude 
than that previously given. 
Tue Aprit METEorIc SHOWER.—Mr. W. F. Denning 
writes :—More favourable weather for meteoric ob- 
servations could scarcely have occurred at the period 
of the Lyrid meteors. At Bristol the fourteen successive 
| nights from April 10 to 23 were clear or generally 
