is, 4 Perkins: Absolute Units and Relativity Principle 343 
6. The apparent hardness of the diamond; 
7. The apparent compressibility of sulphur dioxide (under 
definite pressure and temperature) ; 
8. One thousand and one apparent physical quantities that we 
can measure; 
To find: 
1. Absolute units of length, time, and mass such that, if we 
should send our experimental data on the density of water to 
a scientist on a planet of Sirius, he could interpret the results 
without any reference to his velocity relative to us. 
2. A criterion of absolute simultaneity at two different points 
which shall no*t involve the velocity of those points. 
Now if Bucherer’s experiment on the mafss of an electron 
had preceded the Michaelson-Morley experiment on the veloc- 
ity of light, I suppose the principle of relativity would have 
been deduced from the constancy of the Mass of an Electron, as 
it certainly could have been, because if the mass really varies 
with the absolute motion through space we would get very dif- 
ferent results for one electron going along with the absolute 
motion of the earth and another going against this absolute 
motion. 
Similarly if some brilliant physicist had discovered that the 
compressibility of. sulphur dioxide was remarkably constant, 
whether taken in the direction of the earth’s absolute motion 
or across it, the principle of relativity might have been founded 
on the constant Compressibility of Sulphur Dioxide. 
As it happened, however, the relativity principle was dis- 
covered by means of experiments on the Velocity of Light, so 
the relativists set up the constancy of the velocity of light as 
a “graven image,” and commanded the rest of the world to come 
with them into the mud of “ambiguity,” “clocks,” and “light- 
signals,” and worship it. 
It seems to me that there is only one conclusion that we can 
arrive at from the data that have just been stated.* It may be 
wrong, of course, and some other conclusion may be right; but 
wrong or right, the other conclusion was obtained from some 
other sources than the experimental data. The conclusion that 
corresponds to the data is that every item given represents a 
natural constant which is absolutely independent of uniform mo- 
tion through space. Whether we draw this conclusion or not, 
we can solve the problem, as stated. 
