Procter's Astronomical Lectures. 



facnlro, and yon vrill recognize on the border of tho 

 sun's disk mottled markings, the first sign of the 

 complexity of the solar surface. That is a feature 

 which can be recognized in a telescope of *hreeinches 

 ic aperture. We will have another of those pictures 

 brought on the scene, differing from the last in the 

 fact that there are spots oi considerable size on this 

 view of the sun. These spots are stin-paintcd and 

 actual pictures of the spots themselves. You can 

 recognize the half shadow boundary, and the greater 

 brightness of the interior part the mottled part, 

 the border, and the bright facular streaks. But now 

 we will have pictures of one and the same spot in 

 various stages of its progress, and you will recognize 

 the evidence by which Pr. Wilson of Glasgow in 

 1776 recognized tho fact that spots are depressions 

 below the surface of the sun. 



PECULIARITIES OP THE SPOTS. 



Here are various pictures of the same spot. Thty 

 are all numbered, and you will see, first of all, the 

 spots appearing on the edge of the sun, and you are 

 able to look on the further half shadow part of that 

 spot, and it would seem as if you were looking on 

 the edge. The half shadow part around the dark 

 region becomes more and more uniform in breadth. 

 You see the shape of the spot, and the formation 

 acros-< it of a streak of bright light, and you see it 

 gradually changes in shape. All these spots are ac- 

 tually sun painted, and you will recognize the fact 

 that you are looking on the actual economy of the 

 solar surface, able to review some of the processes 

 rcaiiy taking place there. You may not bo able to 

 find an explanation of these changes of form. They 

 remain still a mystery of astronomy. The processes 

 are continually taking place, although the sun 

 looks so calm and still. I have spoken of the irreg- 

 ularity of the sun's surface, and we will now have a 

 picture showing that irregularity on a larger scale. 

 Father Seccki took a picture of one of those faculae. 

 If you look on the surrounding part as representing 

 the general surface of the sun, you will see that the 

 facuhsare very large, and distinguished from tha 

 rest by their brightness. The irregularities around 

 the faculse are not the rough mottling, but a feature 

 more delicate. This was recognized by Herschel, 

 and railed by him the corrugation. He compared ic 

 to the irieirularity of the surface of an orange. 



Now vou have another picture showing the same 

 corrugations, the whole picture being devoted to 

 that one leatuiv. There are the corrugations, and 

 y..n see them surrounding a small spot without a 

 penumbra, Now you can recognize the justice of 

 Herschel's description. These corrugations have 

 p i v'en rise to a great deal of study in late times. 

 You can recognize the central part of these corruga- 

 tions as bright granules, but in preference I will use 

 the terra " rice-grains," because Prof. Langley has 



found it convenient to distinguish the rice-graina 

 from still smaller spots to which tho name of 

 granules has been given by him. 



The picture next to be shown will indicate tho 

 rice-grains, which are not so delicate as those Prof. 

 Laugley has discovered. Dr. Huggins in England 

 has taken the picture, and from its regular aspect it 

 has been called Dr. Huggins's floor cloth. Still 1 

 have very little doubt that he perceived these gen- 

 eral features. You can see the general darkness of 

 that portion where granules are few. 1'heso 

 dark regions are the dark parts of that mottling 

 which is seen in smaller telescopes. These rice- 

 grains are not in reality small, although they look 

 small in the telescope. Their length is about COO or 

 700 miles, and the breadth about 300 miles ; in other 

 words, they are about as large as Great Britain. 

 [Laughter.] The study of these objects led to a very 

 singular theory. It was thought by one gentleman 

 from the aspect of the spots that the sun is sur- 

 rounded by double coating, the outer giving light, 

 the inner coating only able to reflect the light, but 

 with no power of its own to give light, and that 

 when the inner coating is broken you see through, 

 the dark surface of the sun, and that surface may be 

 so slightly illuminated and heated by surrounding 

 cloud layers, that life may be possible there. Sir 

 John Herschel said that whatever view we michfe 

 form about these rice-grains, it was certain tha 

 greater part of the light and heat of the sun cornea 

 from them, and he thought that vital energy ia 

 living organisms might be the secietof that light; 

 that, because vitality is connected with electricity, 

 and electricity with light, some of these spots of 600 

 miles long by 300 miles wide, might be living crea- 

 tures ! 



OBSERVATIONS OF ASTRONOMERS. 



I now pass to the particular observations whic't 

 suggested these thoughts. On the sun's surface 

 there were observed " willow leaves," which gavo 

 rise to a great deal of controversy as to their char- 

 acter. You all see those willow leaves of Nasmyth. 

 You will notice that the whole of the broad surfaco 

 of the sun appears to be made up by the crossing of 

 a multitude of willow leaves. They appear moro 

 distinctly in the central part, and are very well 

 recognized on the outlying border of the spot. But 

 Avhen that matter was submitted to careful study, it 

 was found that there was great occasion to doubt 

 whether the long willow-leaved streaks existed all 

 over tho surface of the sun, and an astronomer of 

 your own has given a good account of them. 



But before I come to Laugley's work 1 must gire 

 a picture by Father Secchi. It would appear that ho, 

 observing the solar spots in the clear atmosphere of 

 Eome, was able to recognize the true nature of thesa 

 streaks. The general surface of the aun is made up 



