detect the warmth of a young lady's cheek some miles away, failed to record any heat from the stars.
Perhaps you think the heat may get used up on the way because it has to pass through such frightfully cold space. There is no doubt that if we actually took our "Voyage in Space" instead of only pretending, we should be chilled to the marrow very soon indeed. It is terribly cold in space—far colder than we can possibly imagine. You remember the liquid air? Well, cold as that is, it is hot compared with the cold of space. And yet the heat does not get lost in passing through this cold any more than light in passing through simple darkness. If there is anything to stop the light—anything material, such as a dark nebula, however flimsy that is another story; then light would be lost. But if there is nothing of that kind in the way the light can go on for hundreds and thousands of years, and so also can heat. Let me show you rather a pretty experiment. Here is a flask of liquid air—very cold, as you know already. We can pass a beam of light and heat from the lantern through it so that the liquid air will not only transmit the heat, but will focus it like a "burning glass," so that we can set a piece of paper alight. There, you see, the paper is on fire! That is because the liquid air, cold as it is, and the flask containing it, are transparent to heat; and similarly space, cold as it is, is transparent to heat, so that we get the heat of the stars across these immense distances, and though the early experiments to detect it failed, others were more successful. The heat of some stars has been definitely measured.
Now let us turn to quite a different thing concerning the stars; to an announcement made two
