Jury 23, 1914] 
NATURE 
Dad 
It is still the elect to whom it is given to escape 
from the bondage of their own consciousness so 
completely that they can think of time as nothing 
more than the most convenient means of ordering 
events. Sir Oliver Lodge was voicing the feeling 
of the man in the street when, at Birmingham, 
he said: “Surely, we must admit that space and 
time are unchangeable: they are not at the dis- 
posal even of mathematicians.” 
It is not so long since a similar divergence of 
view existed in respect of the other fundamental 
dynamical magnitude mass. But here the con- 
troversy has subsided; the mass of a body is 
still something more than a shadow, though no 
teacher of dynamics would to-day think of defining 
it as “the quantity of matter” in it. Rather the 
conception has gained in concreteness through its 
separation from the crude intuitive notion of heavi- 
ness, through the realisation that no precise de- 
finition is possible apart from the uniformity which 
is expressed in the laws of motion. 
A reader of “The Grammar of Science” might 
well have exclaimed: “From this day forth mass 
is amere shadow.” But no one now would assert 
that mass as a measurable quantity is ana priori 
and obvious concept, independent of the pheno- 
mena of motion. 
Now, apart altogether from the particular 
assumption of the principle of relativity that elec- 
trical phenomena cannot reveal an absolute 
motion, it was implied by its founder that as 
measurable quantities space and time are on ex- 
actly the same footing as mass, in that they 
are inseparable from the uniformities which they 
are used to describe. They are no more at the 
disposal of the metaphysician than of the mathe- 
matician. The psychologist is within his pro- 
vince in endeavouring to elucidate the nature of 
the consciousness of duration, but in the region 
of exact physical measurement this aspect of time 
is eliminated, so that only experiment can say 
whether there is, for instance, a unique sense in 
which two events at different places are simul- 
taneous. It is exactly this which experiment 
has failed to do. Whether it will ever do. so 
cannot be foreseen; the principle of relativity 
seeks to examine some of the consequences of 
assuming that it will not. But it is for the 
present generation to decide whether it is a sound 
scientific principle that time, like other physical 
concepts, is dependent for its significance on the 
observation of uniformity in physical processes, 
and that the reality of it to our minds is only due 
to the unbroken regularity of these processes. In 
this sense we may surely say with Sir Oliver 
Lodge that space and time are unchangeable, but 
at the same time we must leave it to nature to 
tell us what they are, and not foist upon the 
measures of them a metaphysical significance 
borrowed from a conceptual scheme which has 
been outgrown by experiment as the dynamical 
universe conceived by Laplace has been. The 
small volume before us embodies the classical 
papers, in which the gradual transition from the 
Newtonian thought about space and time to this 
point of view is developed. 
NO. 2334, VOL. 93| 
ae 
THE HAVRE MEETING OF THE FRENCH 
ASSOCIATION. 
"THE arrangements are now complete for the 
visit of members of the British Association 
who have been unable to take part in the meeting 
in Australia, to the congress of L’Association 
Frangaise pour l’Avancement des Sciences at 
Havre, beginning on Monday, July 27, and end- 
ing Sunday, August 2. Nearly one hundred mem- 
bers have intimated their intention of availing 
themselves of the courteous and kindly invitation 
with which they have been honoured by the French 
| society. Among them are about fifty delegates of 
the associated and affiliated societies which are 
in correspondence with the British Association. 
The council of that association has approved of 
the holding of a meeting of the conference of dele- 
gates at Havre during the present year, to be 
followed later on, if necessary, by a meeting in 
London for any formal business that may still 
require to be done. 
The session of the conference of delegates will 
be held at Havre on Tuesday, July 28, at 2.45 
p-m., and as it forms part of the accepted pro- 
gramme of the French Association, it is hoped 
that it may be attended by many members of that 
association. It will be presided over by Sir 
George Fordham, who will deliver an address, in 
which he will direct attention to the work of the 
conference, since its establishment in 1885, and 
that will be followed by a discussion, in which 
the functions of local societies will, it is hoped, 
be considered from an eminently practical point 
of view. There is, it is understood, a strong 
feeling among scientific men in France in favour 
of the organisation of local societies in that 
country upon similar principles, and it would be 
very satisfactory if one result of this joint meet- 
ing should be to facilitate the movement in that 
direction. 
At the opening meeting of the congress, to be 
held in the Grand Theatre, Place Gambetta, on 
Monday, July 27, at 2.30, Sir William Ramsay 
will speak as the principal representative of the 
British Association. In the sectional meetings 
on the four following days, several papers will be 
contributed by the English visitors. On Friday, 
July 31, at 2.30, a general Anglo-French meeting 
will be held, at which it is proposed that the 
subject of the Channel Tunnel should be discussed, 
and on the evening of the same day a discourse 
will be delivered by a member of the British Asso- 
ciation in the Grand Theatre. Thursday, July 30, 
will be devoted to an excursion to Rouen, and 
the congress will conclude with a cruise and visit 
to Cherbourg on the Transatlantic steamer La 
Touraine. 
The committee to which the council of the 
British Association has entrusted the making of 
these arrangements owes much gratitude to Dr. 
A. Loir, who two years ago conveyed the invita- 
tion of the French Association to the meeting at 
Dundee, and has been most assiduous in his care 
for the comfort of the English visitors. The invi- 
tation is felt to be a very graceful act on the part 
of the French Association. 
