CoLENSo. — Presidential Address. 143 



appearance will commence about two hundred miles north of 

 Scotland, out at sea, and will cease on the Pacific Ocean at 

 180 degrees of east longitude and 20 degrees north latitude. 

 Though invisible here, I mention it for two reasons : (1.) It is 

 exciting active scientific consideration at Home and through- 

 out the old civilised world, so that great preparations are 

 being made for the proper observation of it. Some months 

 back the " Norse King," a large steamer of 3,000 tons, was 

 chartered to take an astronomical party to Vadso, in Nova 

 Zembla, in order to observe this eclipse ; while similar arrange- 

 ments will also be carried out for Japan. On this occasion 

 two instruments will be used, one called a coelostat and 

 the other a heliostat, their purpose being to deflect the rays of 

 the object into a fixed telescope, instead of having to put the 

 telescope itself into motion. The importance which attaches 

 to the investigation of the sun during eclipses is very great, for 

 it is only at these times, and during brief occasional opportu- 

 nities, tiiat knowledge of its physical construction and condi- 

 tions can be obtained. It is only when the brilliancy of the 

 flood of hght which emanates from its whole surface is shut 

 -off from our eyes by the intervening moon, and we are left in 

 the darkness of the lunar shadow, that we are able to see the 

 corona radiating from the vast orb, and here and there within 

 its zone the remarkable outburst of still more luminous com- 

 bustions — certain brilliant star-like points, commonly called 

 " Baily's beads," and irregular flame-like protuberances on 

 the dark edge of the moon, usually of a pink or rose colour. 

 Although solar eclipses are annually in greater number than 

 lunar eclipses, they are more locally distributed, and, whilst 

 the shadow of the lunar eclipse rests over a full hemisphere, 

 the solar eclipse is a mere streak on the earth's surface. 

 Hence the necessity for expeditions of observers. And (2) to 

 tell you what I have myself observed, in a small way, w'ith 

 reference to the corona radiating from the sun, or, more par- 

 ticularly, those irregular flame-like projections, but not during 

 an eclipse. During several years, in the month of December, 

 and about the middle of it, or on or near to our longest day — 

 the 21st — I have been employed in watching with my glass 

 the sun at sunset and seeing it descend south-Vk^est beyond the 

 Euahine Mountain-range, about fifty miles distant, when two 

 things I have noticed — one being a kind of corona or areola, 

 with long, attenuated, red flames, ever changing, proceeding 

 from its margin (much as the sun is represented in drawings of 

 it when eclipsed), and one an abrupt bare rock or broken pre- 

 cipitous crag on the crest of the mountain standing out in bold 

 relief and black shade in front of the sinking orb. These inter- 

 esting sights are only to be seen for a few evenings, owing to 

 the daily change in the apparent position of the sun travelling 



