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Page:Popular Science Monthly Volume 86.djvu/436

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THE POPULAR SCIENCE MONTHLY

MEASURING HEAT FROM STARS
By Dr. W. W. COBLENTZ

I. Some Questions Answered

IF the title of this paper had been chosen as, "Measuring Heat from Stars—Of What Practical Use Is It Anyway?" it would express the feeling of the average interviewer. The question is not meant to be contemptuous. It is the expression of the mind that figures everything on the basis of an immediate return upon his investment.

The interrogator may be one "engaged in writing an article for some magazine" and he must needs "tell the layman the practical side of the subject." Suppose I, in turn, ask my interrogator the question: "Of what prospective use was your layman when he was in the first stages of development?" Said interrogator shrugs his shoulders, smiles, and admits that perhaps the "layman" is not the only one to be considered; that some of the results of investigations must go into the great storehouse of knowledge, no one knowing what their ultimate use may be; that the great unknown can be explored only step by step; that each achievement may be only one more link in the chain of knowledge, perhaps to be disputed and refuted by some future investigator or perhaps be put to some practical use of some future "layman."

Another question raised is, "Why the Government should be measuring the heat of stars?" not realizing that such activities are incidental, conducted to assist, if possible, its citizens in every possible way. The narrow-gauge college professor may perhaps take it as an intrusion upon his field. To such an one the writer can but tell the lesson taught him some months ago, when one bright morning, on walking through the woods, a loud commotion was heard in the topmost branches of a tall oak tree. Two wood-peewees were quarreling for the possession of this tree—as a place to catch flies! There were hundreds of other trees close by, then why quarrel about this one. How like the scientific man, I thought. We quarrel for fields of research, just as though the heavens were not ablaze with objects for investigation.

A further question asked by the interrogator is, "Well, how do you measure the temperature of the stars?" This question may be easily dismissed by saying that we can not measure the temperature of the stars. The best we can do is to attempt to measure the rate at which they are losing heat. But until the past summer even this attempt was of little interest to the astronomer. Heretofore experimenters were glad to be able to record heat from a few of the brightest stars; let alone attempting to measure stars of the 6.7th magnitude which are about