Strange sound resumes

     Back on February 23rd I wrote about a strange sound that seems to only be present in the library. Before I got a chance to explore into the matter, the sound quit occuring. Its back again, begining last night it was first heard at 7:58pm. Neither of us were in the library at 8:58, or thereabout so we don't know if it repeated at that time; however, it was heard again at 9:58pm and 10:58pm. I await to see if it repeats tonight.