History of sour cocktails
The combination of base spirit, water, sugar and citrus mean that a sour is basically a scaled-down punch.
Punch is the earliest form of cocktail [see history of punch] and due to the similarity in ingredients, many site the punch as being the sours predecessor - and by extension, also of Collinses, Fixes, Daisies, Coolers and Cobblers - what drinks historian David Wondrich calls "The Children of Punch" or "Lesser Punches".
The British Navy is credited for popularising, if not inventing the sour. Rum was readily available around the Caribbean, and unlike beer, didn't go off during long voyages, so rum became the official libation of the British Navy. To help combat scurvy and malnutrition, the sailors often mixed their rum rations with lime juice to make a Daiquiri-like mixture known as Grog, which in turn led to British sailors being nicknamed 'limeys', and the phrase, "Too many and you'll be 'groggy" in the morning." [see Naval rum and the history of the Grog]. Sailors brought Punches and Grogs ashore and Punch Houses where first established in London in the 1600s.
The first record of a Sour appears in 1856, alongside that for a Fix, as part of the hand-written list of the 107 mixed drinks then offered at in the Mart Ackermann's Saloon in Toronto, Canada. The first known written recipe for a Sour appears six years later in Jerry Thomas' 1862 book The Bartender's Guide which has recipes for a Brandy Sour, a Gin Sour and a Santa Cruz (rum sour).
Page 59, The Bartender's Guide 1862
The oldest known mention of a Whiskey Sour comes eight years later in a God-fearing Wisconsin, USA, newspaper, the Waukesha Plain Dealer. "Then may God have mercy on your soul," says I, taking a drink out of me cousin's glass. "Amen" says the Methodist, as he ordered another whisky sour."
Waukesha Plain Dealer, Tuesday 4th January 1870.
The way the whisky sour is mentioned in this 1870 newspaper shows that its popularity is such that it needs no explanation. As David Wondrich writes in Imbibe, "From roughly the 1860s to the 1960s, the Sour, and particularly its whiskey incarnation, was one of the cardinal points of American drinking...." Wondrich illustrates the Sours status with this 1879 quote from the Atlanta Daily Constitution, "When American meets American then comes the whisky sour".
The Sour's simple three-ingredient construction - base spirit, citrus and sweetener, plus water (from ice) adding essential dilution - is replicated in countless cocktail recipes such as that for a Daiquiri and countless others. Indeed, it's the balanced composition of these ingredients which can set excellent craftmanship apart from the rest. A Sour, particularly a Daiquiri is the best test of a bartender's mastery of balance.
What shape and size of glass deemed appropriate for a Sour has changed enormously over the decades. Back in 1862 Jerry Thomas stipulated to "use a small bar glass", but as the sour evolved, the dedicated eponymously named sour glass, a footed glass, deeper than a cocktail glass, became ever more popular and by 1884, in his Bar-Keeper's Handbook George Winter specifies to "use a fancy sour glass" for some sours and a "large bar glass for others.
In his 1908, The World's Drinks and How to Mix Them William Boothby calls for Sour recipes to be strained into a highball or punch-glass. Then in 1912, in his The Hoffman House Bartender's Guide Charles S. Mahoney says the Dizzy Sour and Gin Sour should be served in a sour glass whereas the Whiskey Sour should be served in a claret glass.
Modern-day Whiskey Sours tend to be served on-the-rocks in an old-fashioned glass, but the same drink could be shaken and strained into a stemmed sour glass and served straight-up. When it comes to Sours, as long as the glass is appropriately sized, pretty much anything goes.