_ 
APRIL 25, 1884.] 
Three hypotheses were suggested as to the na- 
ture of the explosive; viz., coal-gas, gunpowder, and 
dynamite. The fact that all the gas apparatus was 
found intact disposed of the first. The absence of all 
residue, and the extremely local and brusque action 
of the explosive, testified unmistakably to the use of 
an agent possessing greater detonative energy than 
gunpowder, while these properties are characteristic 
of dynamite. The finding of a piece of Bickford 
safety-fuze and fragments of copper, presumably from 
a detonator, strengthened this belief. Accepting this 
theory, experiments were made by Col. Majendie, 
together with Professor Abel and Dr. Dupré, to de- 
termine the amount of dynamite necessary to pro- 
duce the observed effects, the switch-rod and gas-pipe 
from the Praed Street tunnel being used in similar 
positions to the charge which they bore there; and it 
was found that two pounds of ordinary dynamite 
would be sufficient, if properly detonated. The cir- 
cumstances surrounding the explosions, however, in- 
dicated that a larger amount — probably five pounds 
— had been used, but that a portion had burned with- 
out explosion. 
The means used for inducing the explosion was 
probably a suitable fuze of such a length as would 
burn for the desired time. This was then attached 
to a detonating-cap, and the latter inserted in a 
zine case containing the dynamite. The assassin 
then boarded a passing train, and, lighting the fuze, 
threw the contrivance from the window, the fuze 
being timed to explode the cartridge under the train 
following. In the case of the Praed Street train the 
explosion was premature, and exploded under the 
_ train in which the assassin was. In the second case 
the explosion occurred at the time designed, but the 
train fer which it was intended was late. In one 
minute more the train would have reached the spot, 
and the result would have been more serious. 
UNIFICATION OF TIME. 
A PART of the minutes of the session of the In- 
ternational geodetic association held in Rome last 
October, embracing the resolutions and discussions 
concerning an international prime meridian and sys- 
tem of expressing time, has been published. The 
resolutions have already appeared, but the discussions 
are now made public. Delegates were present from 
Bavaria, Belgium, France, Italy, Holland, Norway, 
Austria, Prussia, Roumania, Russia, Switzerland, 
Spain, United States, and Great Britain, and the alma- 
nacs were represented by Foerster, Loewy, and Puja- 
zon. 
The French delegates alone seemed to be somewhat 
opposed to the project; and their arguments, singu- 
larly enough, were not altogether unlike those that 
are so commonly urged against the adoption of the 
metrical system of weights and measures in this 
country. 
Mr. Faye admitted the ‘practical and undeniable 
need of a universal system of time;’ but he would 
regret to see the suppression of all the nautical alma- 
SCIENCE. O17 
nacs except that of England as a result of adopting 
the meridian of Greenwich, because ‘these publica- 
tions fed the sacred fire of astronomy.’ ‘‘Still,’’ said 
he, ‘‘the French government may be found more ac- 
cessible to the proposal, if it be brought to the con- 
viction that the reform would be advantageous from 
the point of view of general civilization;’’ which we 
may interpret as meaning, ‘“‘if England will adopt 
the metric system in return.’’ Professor Foerster 
thought it a strange phenomenon tosee scientific men 
more narrowly nationalistic upon scientific questions 
than the nations and governments themselves. He 
considered it wicked to multiply repetitions of sub- 
stantially the same calculations of ephemerides in the 
different countries merely to ‘feed the sacred flame 
of astronomy;’ or, in other words, to find support for 
computers. 
Col. Perrier urged that the adoption of a distant 
meridian would be found extremely inconvenient in 
topographical maps; but Dr. Hirsch replied, that the 
meridian of Greenwich would hardly be more unfa- 
vorable than that of Paris for the eastern parts of 
France; and Helmholtz pointed out, that Germany, 
which had during a long period used the meridian of 
Ferro, had experienced no inconvenience from its 
being so distant. 
Mr. Yvon Villarceau held, that any reform of the 
system of reckoning longitudes and time should be 
accompanied by a decimal division of the circle and 
of the day. But the idea of sweeping away the divis- 
ion of the day into twenty-four hours met with no 
favor; though the conference consented to a resolu- 
tion expressing the ‘incontestible advantages of a 
decimal division,’ not of the circle, but of the ‘ quad- 
rant of the circle, in extensive calculations.’ 
Mr. Loewy, the director of the Connaissance des 
temps, was more decidedly hostile to the change than 
any other delegate. He thought its advantages slight, 
its inconveniences considerable; and he could not con- 
sent to changing the usage of centuries in the arrange- 
ment of an ephemeris, without the most conclusive 
reasons. Professor Foerster in reply, holding the 
Connaissance des temps for 1884 in his hand, showed 
the great simplifications which would result from the 
change, and added, that Loewy himself had, in his 
direction of that ephemeris, been one of the most 
radical of innovators, and had certainly modified the 
arrangement far more than the proposed reform 
would do. 
Notwithstanding the objections of the French mem- 
bers, some of whom voted against single resolutions, 
when the question was put, whether the body of 
resolutions should be adopted as a whole, it was car- 
ried unanimously, Loewy alone not voting. A very 
gratifying degree of accord may therefore be said to 
have been reached. Mr. Christie, the astronomer 
royal, declared his personal sympathy with the reso- 
lution expressing the hope that Great Britain might 
enter into the metre treaty, while explaining that he 
was not authorized by his government to encourage 
that hope. After the adoption of the resolutions, 
Gen. Cutts, the delegate of the coast survey and of 
the American government, which, it will be remem- 
