There isn't an actual drink called a highball. Highballs are more like a genre of drinks. Very simply they are a distilled alcohol mixed with a larger portion of nonalcoholic diluent. There is no classic ratio, it's drinker's choice. Some classic examples of highballs are Scotch and Soda, Jack and Coke, Rum and Coke, Gin and Tonic, and the list goes on.
For those that don't know, Philip Marlowe is the famous fictional detective in the crime noir novels of Raymond Chandler. Often these stories were called "hardboiled" because they were tough and violent. Some of the titles of the Marlowe books might be more familiar to people because of their early movie adaptations: The Big Sleep (starring Humphrey Bogart as Marlowe) and Lady In The Lake (this time with Robert Montgomery in the part).
In the novels there was always a bottle of rye whiskey hiding out in a drawer or cabinet somewhere and often this was mixed with ginger ale or seltzer.
Step 1: The Parts
* Ginger Ale - Since this is meant to be a drink for a hardboiled detective I choose Vernor's, a rough ginger ale.
And that's pretty much it. A glass and some ice and a spoon to stir with.
I use 2 ounces of rye per glass. Pour it in and top it off with ginger ale.