492 THE POPULAR SCIENCE MONTHLY. 



As in all such cases, our interest in the phenomena increases in pro- 

 portion to our understanding of their significance and their true scale 

 of magnitude. In glancing from side to side of the sun's disk, the eye 

 ransres over a distance of more than 860,000 miles not a mere ideal 

 distance, or an expanse of empty space, but a distance filled by an 

 actual and, so to speak, tangible body, whose diameter is of that stu- 

 pendous magnitude. One sees at a glance, then, the enormous scale 

 on which these spots are formed. The earth placed beside them would 

 be but a speck, and yet they are mere pits in the surface of the sun, 

 filled perhaps with partially cooled metallic vapors, which have been 

 cast up from the interior, and are settling back again. It is worth 

 anybody's while to get a glimpse at a sun-spot if he can, for, although 

 he may see it merely as a black dot on the shining disk, yet it repre- 

 sents the play of physical forces whose might and power are there 

 exercised on a scale really beyond human comprehension. The im- 

 agination of Milton or Dante would have beheld the mouth of hell 

 yawning in a sun-spot. 



In order to view the sun, it is, of course, necessary to contrive some 

 protection for the eyes. This may be constructed by taking two strips 

 of glass four or five inches long and an inch wide, and smoking one of 

 them until you can without discomfort look at the sun through it. 

 Then place the two strips together, with the smoked surface inside 

 taking care to separate them slightly by pieces of cardboard placed 

 between the ends and fasten the edges together with strips of paper 

 gummed on. Then, by means of a rubber band, fasten the dark glass 

 thus prepared over the eye-end of your opera-glass in such a way that 

 both of the lenses are completely covered by it. It will require a little 

 practice to enable you to get the sun into the field of view and keep 

 it there, and for this purpose you should assume a posture sitting, if 

 possible which will enable you to keep the glass very steady. Then 

 point the glass nearly in the direction of the sun, and move it slowly 

 about until the disk comes in sight. It is best to carefully focus 

 your glass on some distant object before trying to look at the sun 

 with it. 



As there is some danger of the shade-glass being cracked by the 

 heat, especially if the object-glasses of the instrument are pretty large, 

 it would be well to get the strips of glass for the shade large enough 

 to cover the object-end of the instrument instead of the eye-end. At 

 a little expense an optician will furnish you with strips of glass of 

 complementary tints, which, when fastened together, give a very pleas- 

 ing view of the sun without discoloring the disk. Dark red with dark 

 blue or green answer very well ; but the color must be very deep. 

 The same arrangement, of course, will serve for viewing an eclipse 

 of the sun. 



