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is bad, and if permitted will greatly militate against con- 
venience and uniformity in using the current both for 
light and for motive-power. Where the undertakers dis- 
tribute “alternating”? currents it is provided that the 
mains should have a ‘‘ constant (?) difference of potential”’ 
or standard pressure of not less than forty-five and not 
more than six hundred volts. Here again we think that 
the Board of Trade might very wisely insist on a further 
restriction. If steady currents at a pressure of four 
hundred volts are dangerous, alternating currents at four 
hundred are far more so. Yet here the undertakers talk 
of six hundred! Indeed, considering the risks involved, 
and the difficulty in distributing alternating currents 
through long lines or lines where there is great self-induc- 
tion; and also considering that the supply of electric 
currents is not for lighting alone but for the providing 
also of motive-power, it would not be any loss to the 
public if the use of alternating currents under the pro- 
visional orders were absolutely disallowed. It is true 
that the patentees of certain specific forms of machine 
might cry out loudly against such a prohibition; but the 
public would be guaranteed against one source of danger 
and difficulty. According to the orders the undertakers 
may charge consumers either by the amount of electric 
energy consumed, or by the quantity of electricity sup- 
olied, or by time, or by a yearly agreement. In connection 
with the first of these methods the proposal is made to 
call by the name “one unit” the energy contained in a 
current of r0o0co amperes flowing under an electromotive 
force of one volt during one hour. Most of the pro- 
visional orders name sevenpence per unit as the price of 
electrical energy. We have here for the first time an 
actual quotation-price for evevgy; a fact which should be 
mteresting to those who have striven so hard to drive 
mto the popular mind exact ideas concerning energy and 
its conservation. One “unit’’ thus defined for commercial 
purposes being 1000 volt-amperes (z.e. 1000 watts) for one 
hour, and one horse-power being 746 watts, we see that 
the scale of payment is about 54 pence per hour per 
(electrical) horse-power. 
Into the further provisions for the inspection and test- 
ing of mains, the inspection of meters, the testing of 
insulation, provisions for safety, and penalties for default 
in supply, we cannot here enter. Suffice it to say that 
there is no detail that does not appear to have had thought 
expended upon it, no provision that is really superfluous 
or harassing, no possible want or eventuality that does 
not appear to have been anticipated. Such masterly 
treatment cannot but greatly facilitate the work of the 
Board of Trade in agreeing to orders and licenses, and 
will tend to bring about unity of method in the organisa- 
tion of the actual work of laying down town supplies so 
soon as such orders and licenses shall have been granted. 
If it be true that the effect of the Electric Lighting Act 
has been to produce a temporary lull in the progress of 
electric lighting, we are convinced that such a lull will be 
in the end an unmixed good, since it gives the oppor- 
tunity for thought to ripen, and for projects and inven- 
tions to mature, if not to survive. Two dangers indeed 
seem yet possible in the future of public electric lighting, 
and either of them may be sufficiently serious to damage 
public confidence in this new industrial factor. Firstly, 
some better guarantees ought to be insisted on that the 
NATURE 
385 
Companies or other parties who obtain orders or licenses 
as undertakers should be possessed of capital adequate to 
carry out the projects in hand. A very hasty glance at 
the list of applicants for provisional orders will suffice to 
show that this fear is not unfounded. Secondly, it ought 
to be made impossible for a Company which has obtained 
an order for any limited district to delegate the responsi- 
bility of supplying any section of such district to a sub- 
company. No Company should be allowed to hold a 
monopoly (if the limited monopoly created by the pro- 
visions of the Electric Lighting Act be a monopoly at all) 
of a single square yard of territory which it cannot with 
its own resources supply under the terms of the order or 
license which has been granted. If this principle be not 
upheld, serious abuses will creep in, to the detriment of 
progress and in contravention of the interests of the 
public. 
CRYPTOGAMIC FLORA OF GERMANY, 
AUSTRIA, AND SWITZERLAND 
Dr. L. Rabenhorst’s Kryptogamen-Floravon Deutschland, 
Oesterreich, und der Schweiz. Zweiter Band: Die 
Meeresalgen Deutschlands und Oesterreichs. Bear- 
beitet von Ferdinand Hauck. 1-3 Lieferung. (Leipzig : 
Eduard Kummer, 1883.) 
INCE the appearance of the original work (1845-53) 
the systematic study of living alge has, through a 
more accurate knowledge of the structure and fructifica- 
tion of these plants, led to great changes in their diagnosis 
and classification. Hence the necessity of a new edition 
of Rabenhorst’s work. 
In order to render it more valuable, the preparation of 
the parts of which it is composed have been intrusted to 
authors specially conversant with the subjects of which 
they treat. The first volume, five numbers of which have 
already appeared, contains the Fungi, and is edited by 
Dr. G. Winter of Zurich; the second comprises the 
Marine Algz (exclusive of the Diatomacez); then will 
follow the Fresh-water Algz, edited by Herr Paul Richter 
of Leipzig; the Diatomacee, by Dr. A. Grunow of 
Vienna; and the Frondose Mosses and Hepatice, by 
Herr G. Limpricht of Breslau. To these will succeed 
works on the Lichens, Charice, and Vascular Crypto- 
gams. 
The second volume, which forms the immediate subject 
of this notice, has been intrusted to M. F. Hauck, who, 
from his residence on the coast at Triest, has, during 
many years, had opportunities of studying marine alge in 
a living state; and by his connection with German and 
other algologists, has been able to obtain authentic ex- 
amples of most of the species. It may also be mentioned 
that M. Hauck has published “ A List of the Algze of the 
Adriatic” (Beitr. 2. Kenntn. d. adriat. Algen, Wien, 
1878). 
The present work, of which three numbers have ap- 
peared, includes not only the algz inhabiting the Austrian 
coast and islands of the Adriatic, but also those of the 
Baltic and North Seas, and the coasts of Heligoland with 
the adjacent islands: the latter have been found especially 
rich in species. 
In the Introduction to his work, M. Hauck gives in- 
structions for the collection and preparation of the various. 
