Dog days sometimes used for the lethargic summer markets. Various computations of the dog days have placed their start anywhere from 3 July to 15 August and lasting for anywhere from 30 to 61 days. They may begin or end with the cosmical rising or heliacal rising of either Sirius in Canis Major or Procyon (the "Little Dog Star") in Canis Minor and vary by latitude, not even being visible throughout much of the Southern Hemisphere. Sirius observes a period of almost exactly 365¼ days between risings, keeping it largely consistent with the Julian but not the Gregorian calendar; nonetheless, its dates
Sirius to have traditional astronomical knowledge about Sirius that would normally be considered impossible without the use of telescopes. In 1938 Marcel Griaule produced his dissertation and received his doctorate degree from the École pratique des hautes études (EPHE) based on his research work with the Dogon. According to Griaule's books "Conversations with Ogotemmêli" 1965 and "The Pale Fox" 1972 they knew about the fifty-year orbital period of Sirius and its companion prior to western astronomers. They also refer to a third star accompanying Sirius A and B. Robert Temple's 1976 book "The Sirius Mystery", credits them with knowledge of the