\Dog" days`\
A period of from four to six weeks, in the summer, variously
placed by almanac makers between the early part of July and
the early part of September; canicular days; -- so called in
reference to the rising in ancient times of the Dog Star
(Sirius) with the sun. Popularly, the sultry, close part of
the summer.
Note: The conjunction of the rising of the Dog Star with the
      rising of the sun was regarded by the ancients as one
      of the causes of the sultry heat of summer, and of the
      maladies which then prevailed. But as the conjunction
      does not occur at the same time in all latitudes, and
      is not constant in the same region for a long period,
      there has been much variation in calendars regarding
      the limits of the dog days. The astronomer Roger Long
      states that in an ancient calendar in Bede (died 735)
      the beginning of dog days is placed on the 14th of
      July; that in a calendar prefixed to the Common Prayer,
      printed in the time of Queen Elizabeth, they were said
      to begin on the 6th of July and end on the 5th of
      September; that, from the Restoration (1660) to the
      beginning of New Style (1752), British almanacs placed
      the beginning on the 19th of July and the end on the
      28th of August; and that after 1752 the beginning was
      put on the 30th of July, the end on the 7th of
      September. Some English calendars now put the beginning
      on July 3d, and the ending on August 11th. A popular
      American almanac of the present time (1890) places the
      beginning on the 25th of July, and the end on the 5th
      of September.