This is about the very lowest temperature yet experienced on the earth's surface.

To understand how such results are obtained a few words must be said about the absolute zero of temperature.
_The Zero of Temperature._ Heat is now believed to be entirely due to ether-vibration, which produces a correspondingly rapid vibration of the molecules of matter, causing it to expand and producing all the phenomena we term 'heat.' We can conceive this vibration to increase indefinitely, and thus there would appear to be no necessary limit to the amount of heat possible, but we cannot conceive it to decrease indefinitely at the same uniform rate, as it must soon inevitably come to nothing.

Now it has been found by experiment that gases under uniform pressure expand 1/273 of their volume for each degree Centigrade of increased temperature, so that in passing from 0 deg.

C.to 273 deg.

C.they are doubled in volume.