162 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1913. 



We will now consider a deforming action dependent also on 

 Newton's law but of a differential nature and consequently propor- 

 tional to the inverse cube instead of the inverse square of the distance. 

 This difference helps to compensate for the inferiority of the mass 

 of the earth with reference to the greater planets and gives it a chance 

 for an honorable rank in this contest. 



We have under our eyes an encouraging phenomenon. The attrac- 

 tion at the surface of the earth due to the sun is but a small fraction 

 compared to the weight of a body here, and the yet feebler attraction 

 due to the moon can not lighten a body by one one-hundred thou- 

 sandth part of its weight. Yet we see the moon exerting this power 

 and indeed with three times more strength than is felt from the sun, in 

 deforming our globe. This action can be detected upon the atmos- 

 phere, the oceans, and even the solid crust of the earth. The seas, 

 however, are what render it most evident to our eyes. Under favor- 

 able conditions, for instance, in the Bay of Mount St. Michel, on the 

 French coast, we see the sea following faithfully the passage of the 

 moon across the meridan. The sea's level changes at the flood some 

 20 meters in a few hours, displacing the shoreline several Irilometers. 

 The work thus developed, if we could only put it to use economically, 

 would be enough to render useless aJl our oil wells and all the engines 

 in the world. 



We may find that no planet is as favorably situated to trouble the 

 sun as the moon is the earth. But perhaps we should not be so ex- 

 acting. We see upon the sun no such liquid seas which might be 

 made to extend or contract their domains. The weight there to be 

 conquered is great, 27 times greater than here. Despite that, we 

 see chances that the sun may react as actively, or even more actively, 

 than the earth, under the action of a distant body. We are indeed 

 led by several converging paths of reasoning to think that the sur- 

 face layers of the sun are to a great depth formed of extremely tenu- 

 ous mobile matter, little subject to the action of weight and all 

 ready, consequently, to obey the least force. 



A first piece of evidence along this line is the development of spots, 

 rents which seem to appear in the luminous veil of the solar surface, 

 reaching in a few days an extent of ten, twenty, or thirty thousand 

 kilometers and disappearing with equal rapidity. In the spectrum 

 of these spots there is an increase in the number and intensity of the 

 absorption bands, leading us to think that various metallic molecules 

 of considerable atomic weight are spouted out in torrents, carried 

 along by currents of the lighter hydrogen. 



More impressive yet is the appearance of protuberances — clouds 

 which develop and remain at heights where they could not be sus- 

 tained by the dense and refringent atmosphere. Much less bright 



