But now the stirring events in the arctic regions which had so held and enthralled them day by day had, after a time, ceased. Mr. Gibbs was engaged in making experiments, observations, and explorations, the result of which he would embody in carefully prepared reports, and Sammy's daily message promised to be rather monotonous. Roland Clewe felt the great importance of a thorough exploration and examination of the polar sea. The vessel he had sent out had reached this hitherto inaccessible region, but it was not at all certain that another voyage, even of the same kind, would be successful. Consequently he advised those in charge of the expedition not to attempt to return until the results of their work were as complete as possible. Should the arctic night overtake them before they left the polar sea, this would not interfere with their return in the same manner in which they had gone north, for in a submarine voyage artificial light would be necessary at any season. So, for a tune, Roland and Margaret withdrew in a great measure their thoughts from the vicinity of the pole, and devoted themselves to their work at home. When Roland Clewe had penetrated with his Artesian ray as deeply into the earth beneath him as the photic power of his instrument would admit, he had applied all the available force of his establishment--the men working in relays day and night--to the manufacture of the instruments which should give increased power to the penetrating light, which he hoped would make visible to him the interior structure of the earth, up to this time as unknown to man as had been the regions of the poles. Roland had devoted a great deal of time to the arrangement of a system of reflectors, by which he hoped to make it possible to look down into the cylinder of light produced by the Artesian ray without projecting any portion of the body of the observer into the ray. This had been done principally to provide against the possibility of a shock to Margaret, such as he received when he beheld a man with the upper part of his body totally invisible, and a section of the other portion laid bare to the eye of a person standing in front of it. But his success had not been satisfactory. It was quite different to look directly down into that magical perforation at his feet, instead of studying the reflection of the same, indistinctly and uncertainly revealed by a system of mirrors. Consequently the plan of reflectors was discarded, and Roland determined that the right thing to do was to take Margaret into his confidence and explain to her why he and she should not stand together and look down the course of the Artesian ray. She scolded him for not telling her all this before, and a permanent screen was erected around the spot on which the ray was intended to work, formed of Venetian blinds with fixed slats, so that the person inside could readily talk and consult with others outside without being seen by them.