avoid the blue stars of less than the fourth magnitude, owing to the difficulty in measuring their radiations. However it was found possible to measure the heating effect of red stars down to the 6.7 magnitude.

Fig. 3. Ironclad Thomson Galvanometer Used in Measuring the Electric Current Generated by the Thermocouples. One of the iron shields Is shown to the right.

If it had been merely an attempt to show the possibilities of the instruments, then by selecting red stars, and by increasing the galvanometer sensitivity, positive indications could have been obtained of radiation from stars of the eighth to ninth magnitude. That, however, would have been simply a spectacular achievement, to awe the layman, and under the present conditions of observation, could not contribute much to science.

The aim was to do one thing thoroughly, rather than to attempt a varied program. This one thing was the establishment beyond all reasonable doubt, by two distinct methods, that the red stars as a