Then they needed to be derived from some aspect of the underlying fabric of the Universe that was not anthropocentric, that did not depend on where you are located when you measure it, or when the measurement was made. This ruled out traditional approaches to standards which took a standard mass of a kilogram or a length of a metre and kept them in a specially controlled environment somewhere and just compared other reference masses or lengths to them. These masses and lengths are anthropocentric in origin but, what is worse, they are anthropocentric in principle because there is no way in which to tell extraterrestrials how much mass or length defines our standard without sending it to them.

In order to escape the shackles of anthropocentric bias Stoney looked to the constants of physics to supply something that might transcend human standards of quantity. Newton had discovered that gravity obeys an apparently universal law. The force between two masses whose centres are separated by a distance is proportional to each of their masses and inversely proportional to the square of the distance between their centres. The constant of proportionality should be the same everywhere in the universe.34 This constant, G, gives a measure of the strength of gravity. The important thing about it is that it is believed to be constant35 – the same value should be found everywhere it is correctly measured. Moreover, it has a strange value when expressed in our convenient anthropocentric units (G = 6.67259 × 10–11m3s–2kg–1) because those units were devised for other anthropocentric purposes.

The second constant of Nature that Stoney appealed to for his non-anthropocentric standards was the speed of light, c. Again, this quantity transcends human standards. It has a fundamental significance. In fact, it has an even more fundamental significance than Stoney could ever have known. Einstein showed that the speed of light in a vacuum should act as the ultimate speed limit in the Universe – no information can be sent faster. It had also been discovered that the product of the permeability and permittivity of space that defined different units of electricity equals the inverse square of the speed of light, so revealing its special universal status with respect to electricity as well. To these two constant quantities Stoney added his own candidate for the third great constant of Nature – his basic electron charge, which we now label by the symbol e. It was the last piece needed to complete the jigsaw. It fitted the bill in the same way as Gand c. It was presumed to be universal. It was associated with a fundamental aspect of the structure of Nature. And it didn't care about human convenience. Stoney announced his trinity of constants like this:36

‘Nature presents us with three such units and that if we take these as our fundamental units, instead of choosing them arbitrarily, we shall bring our quantitative expressions into a more convenient, and doubtless into a more intimate, relation with Nature as it actually exists.

For such a purpose we must select phenomena that prevail throughout the whole of Nature, and are not simply associated with individual bodies. The first of Nature's quantities of absolute magnitude to which I will invite attention is that remarkable velocity of an absolute amount, independent of the units in which it is measured, which connects all systematic electrostatic units with the electromagnetic units of the same series. I shall call this velocity V1 [i.e. our c]. If it were taken as our unit velocity we should at one stroke have an immense simplification introduced into our treatment of the whole range of electric phenomena, and probably into our study of light and heat.

Again Nature presents us with one particular coefficient of gravitation, of an absolute amount independent of the units in which it is measured, and which appears to extend to ponderable matter of every description throughout the whole material universe. This coefficient I shall call l [i.e. our G]. If we were to take this as our unit of coefficients of attraction, it is presumable that we might thereby lay the foundation for detecting wherein lies the connection which we cannot but suspect between this most wonderful property common to all ponderable matter, and the other phenomena of nature.

And, finally, Nature presents us in the phenomenon of electrolysis, with a single definite quantity of electricity which is independent of the particular bodies acted on … This definite quantity of electricity I shall call E1 [i.e. our e]. If we make this our unit quantity of electricity, we shall probably have made a very important step in our study of molecular phenomena.

Hence we have very good reason to suppose that in V1, Gl, and E1, [i.e. c, G and e] we have three of a series of systematic units that in an eminent sense are the units of Nature, and stand in an intimate relation with the work which goes on in her mighty laboratory.

We have thus obtained … the three great fundamental units offered to us by Nature, upon which may be built an entire series of physical units deserving of the title of a truly Natural Series of Physical Units.’

In his talk Stoney referred to the electron as the ‘electrine’ and gave the first calculation of its expected value.37 He showed that the magic trio of G, c and e could be combined in one way, and only one way, so that a unit of mass, a unit of length and a unit of time are created from them.