The tomb of Quoyness is found on Sanday, while Vinquoy Hill is located on Eday. Finally, there is an unnamed tomb on the Holm of Papa Westray. Anna Ritchie reports that there are three more Maeshowe type tombs in Orkney but she doesn't name or locate them. According to the description herein, a chambered tomb is normally characterized by grave goods, which were found at Cuween Hill and the tomb on Holm of Papa Westray (see the paragraph above) but were not found at Maeshowe. Further, the description of a passage grave states: "Not all passage graves have been found to contain evidence of human remains. One such example is Maeshowe." In addition, the Statement of Significance (cited below in the section describing the Maeshowe World Heritage designation) says, "It is an expression of genius within a group of people whose other tombs were claustrophobic chambers in smaller mounds.". A potential explanation for the extraordinary genius of Maeshowe engineering and the lack of human remains was described by Tompkins (1971) who compared the structure at "Maes-Howe" to the Great Pyramid (p. 130-133), suggesting the site was used as an observatory, calendar, and for May Day ceremonies rather than as a tomb. Tompkins (1971) extensively studied numerous documents related to the measurement and exploration of the Great Pyramid of Giza. He stated the central "observation chamber" (p. 130) at Maeshowe was "corbeled like the Great Pyramid's Grand Gallery", was carefully leveled, plumbed", and the jointing is of a quality that "rivals that of the Great Pyramid". Rather than chambers of a tomb, Tompkins suggested the structure contained small "retiring rooms for the observers" (p. 130). He suggested the entrance was very similar to Egyptian pyramids in that it had a "54-foot observation passage aimed like a telescope at a megalithic stone [2772 ft. away] to indicate the summer solstice" (p. 130) in addition to its "Watchstone" to the West that indicated the equinoxes. The "sighting passage" (p. 133) points to a northern star like the pyramids of Saqqara, Dashur and Medûm. Tompkins stated that "The similarity [of the pyramids] to the structure at Maes-Howe is indeed amazing" (p. 133).