APRIL 11, 1907 | 
NATURE 
571 
early report summed up the entire connection between the 
various units as follows :— 
““A battery or rheomotor of unit electromotive force 
will generate a current of unit strength in a circuit of 
unit resistance and in the unit of time will convey a unit 
quantity of electricity through the circuit and do a unit 
of work or its equivalent.” 
Mr. Duddell’s report on the proceedings at the St. 
Louis Conference brought up the question of electrical 
standards in its present-day phase. Mr. Duddell referred 
to two important resolutions passed at St. Louis, and the 
question of giving effect to these was considered. Since 
then matters have progressed considerably, and a con- 
ference was held at Charlottenburg at which represent- 
atives from America, Austria, Belgium, France, Germany, 
and Great Britain were present, and the following resolu- 
tion was adopted :— 
““In view of the fact that the laws of different countries 
in relation to electrical units are not in complete agree- 
ment, the conference holds it desirable that an official 
conference should be held in the course of a year with 
the object of bringing about this agreement.”’ 
The result of the above resolution is that a future con- 
ference will be held this year in London, when the ques- 
tion of the fundamental electric units will be brought up. 
Only two electrical units will be chosen as fundamental 
ones, and these will in all probability be the international 
ohm, defined by the resistance of a column of mercury, 
and the international ampere, defined by the deposition of 
silver. 
The international volt will depend on the above two 
definitions. Experiments have been going on in all 
countries since October last to determine with extreme 
accuracy the quantity of silver deposited in a given time 
and the best method of constructing practical standards 
having a resistance of one ohm, and these results will be 
considered at the conference to be held in London this 
autumn, when we may hope that definitions of the inter- 
national ohm and ampere will be finally settled. 
Not only is it necessary that the fundamental units of 
electrical science should be the same throughout the world, 
but the conviction has grown stronger that the extension 
of this principle would be of enormous assistance to the 
welfare of nations in general, and consequently inter- 
national standardisation has become of the greatest 
importance. 
At the St. Louis Congress two years ago Colonel 
Crompton introduced this question, with the result that 
it was unanimously agreed that the cooperation of the 
technical societies should be secured in order that the 
questions of the standardisation of the nomenclature and 
ratings of electrical apparatus and machinery might be 
thoroughly discussed. The Institution of Electrical 
Engineers appointed an executive committee for this pur- 
pose, and practically all the civilised nations of the world 
cooperated. 
In this way the International Electrotechnical Com- 
mission was formed, and the central offices are for the 
present in London, at the offices of the Institution of 
Electrical Engineers. 
The task before the commission is a large one, as the 
nomenclature alone will probably occupy its attention for 
a considerable period if one may judge by the labour 
entailed in the work of the electrical committees of the 
Engineering Standards Committee, which have been sitting 
lately. 
Standardisation has its dangers as well as its advantages, 
and it is in the avoidance of the one and the utilisation 
of the other that the great difficulty attendant on the 
work of such a commission will consist. It is to be hoped 
that a happy mean may be found, which, while reducing 
the number of types of machinery which the responsible 
consumer or the consulting engineer can order, will not 
stultify the inventive faculties of engineers towards future 
developments. 
Dr. Glazebrook further gives details of the reports of 
the Engineering Standards Committee on the various 
sections of engineering work on which it has already re- 
ported, the reading of which is of the greatest interest. 
The work appears to have been done in a way that is 
NO. 1954, VOL. 75| 
thorough and complete, and every endeavour has been 
made throughout to increase the facilities for obtaining 
greater Output per machine and to reduce the multipli- 
cation of patterns. 
It is gratifying to know that the work is already bear- 
ing fruit, and the recommendations have been adopted 
by the Government Departments, Lloyd’s Registry, the 
British Corporation, and several other registry societies 
in regard to ship and boiler specifications. With regard 
to rails, the Railway Engineers’ Association are adopting 
the standards, and with but few exceptions every new 
tramway system in this country and many in the colonies 
which are under construction are being provided with these 
standard rails. It is estimated that the saving to the 
British manufacturer by standardisation of iron and steel 
sections alone will amount to some millions sterling, and 
we do not think that this figure is exaggerated when 
we take into consideration the fact that the frequent 
changing of the rolls to produce in small quantities 
“ec 
the many 
with. 
Although dealing with an infinitesimal part of this vast 
subject, the address opens out a most important question 
which will have to be considered, not only by the various 
branches of the engineering profession, but by every 
Government that has the welfare of its nation in view. 
Dr. Giazebrook is to be heartily thanked for the clearness 
with which he has dealt with his subject, and there is no 
doubt that his presidential address to the Institution of 
Electrical Engineers will long be remembered by those who 
were fortunate enough to hear it. is eM: 
special ’’ sizes asked for would be done away 
THE INFLUENCE OF PARASITES ON THEIR 
HOSTS. 
SCIENCE of February 8 contains the report of an 
interesting and suggestive address on this subject 
delivered by Prof. H. B. Ward before the Section of 
Biology of the American Association for the Advancement 
of Science at the New York meeting held in December 
last. (For other presidential addresses see Nature of 
February 7, p- 352-) 
After certain preliminary remarks, Prof. Ward mentioned 
that some parasites, such as the distome Heterophyes, 
found in the intestine of Egyptian fellahin, seem to have 
no appreciable effect on their hosts. The African eye- 
worm (Filaria loa), except when it actually enters the 
sclerotic of the eye, affords another instance. Many 
encysted worms likewise come under the same category. 
As a rule, single parasites leave no lasting effects on 
their hosts; it is rather the multiplication of parasites 
which should be dreaded. The most serious effects occur 
when this multiplication takes place within the host. On 
the other hand, when multiplication takes place during 
successive generations in other hosts, it is unlikely that 
the parasites, when in the proper stage, will reach the 
original host in sufficient numbers to cause serious mis- 
chief. The real danger lies in a multiple infection through 
the numerical increase which such a species often under- 
goes in the intermediate host, or within a limited external 
area, so that by the intake of a single object a swarm 
may be introduced. 
As a rule, the harm caused by a parasite bears some 
proportion to its size as compared with that of its host; 
when, however, parasites occupy positions in connective 
tissue or between muscular fibres they may be relatively 
harmless, no matter what their size. 
Some parasites cause harm in a mechanical manner, by 
blocking, for instance, natural passages, or, as in the 
case of the Egyptian blood-fluke, by the ova entering the 
capillaries, when serious trouble is bound to ensue. 
Embryos, in the case of filaria, may likewise infest 
the lymphatic vessels, to the great detriment of their 
host. 
The migrations of parasites, as when Ascaris lumbricoides 
passes along the natural gangways from the intestine to 
the liver, may also cause serious harm, as abscess of the 
latter organ. But parasites do not always confine them- 
selves to such natural lines of movement; they may drive 
