"The Greek Interpreter"

The Greek Interpreter.

The case begins on Wednesday, June 20, 1888.

Why?

TIME HOLMES AND WATSON HAVE BEEN FRIENDS:
"During my long and intimate acquaintance with Mr. Sherlock Holmes I had never
heard him refer to his relations, and hardly ever to his own early life."

THE SEASON OF THE CASE:
"It was after tea on a summer evening . . ."

A SIGNIFICANT ORBITAL COMMENT:
"The conversation, which had roamed in a desultory, spasmodic fashion from golf clubs to the causes of the change in the obliquity of the ecliptic . . ."

THE NIGHT OF THE CASE:
"This is Wednesday evening," said Mr. Melas. "Well, then, it was Monday
night — only two days ago, you understand — that all this happened."

THE RESIDENTS OF 221B:
"We had reached our house in Baker Street . . ."

AND A MUCH LATER EVENT:
"Months afterwards a curious newspaper cutting reached us from Buda-Pesth."

WHAT THE BARING-GOULD ANNOTATED SAYS:
September 12, 1888. 

WHAT ZEISLER, THE KING OF CHRONOLOGY, SAYS:
August 15, 1888.

THE BIRLSTONE RAILWAY’S TIMETABLE:
The obliquity of the ecliptic isn’t something that comes up every day in casual conversation. In fact, it really is only particularly pertinent on two days of the year: the summer solstice and the winter solstice, the high and low points of the Earth’s cock-eyed spin around the sun. Well, we know it’s summer. We know that summer solstice usually occurs on June 21. And we know it’s Wednesday. The only pre-Reichenbach date on which the summer solstice occurs on a Wednesday is in 1882 — far too early for Holmes and Watson to have had a "long and intimate acquaintance." 

The years 1887 and 1888 are somewhat likely candidates, as Wednesday falls the day after and the day before summer solstice, respectively, in those years. But Holmes, being a forward-thinking individual, was most likely anticipating the solstice that would occur in the early morning hours of the next day. Therefore, I’m calling this one as beginning on Wednesday, June 20, 1888.