This section is from the book "The Home Cyclopedia Of General Information", by Charles Morris. Also available from Amazon: Home Cyclopedia of Necessary Knowledge.
Sirius, the brightest of the fixed stars in the Canis Major or Greater Dog constellation. The conjunction of the rising of the dogstar with the rising of the sun was thought by the ancients to be the cause of the great heat of summer and the consequent sickness, and the period of six weeks from the middle of July was hence named dog-days.
 
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