In a recent appearance on "Late Night with David Letterman," actor Richard Harris was ruminating on how a strong belief in heaven keeps his fellow Irishmen at ease with facing death. His only personal concern, Harris declared looking skyward, was whether one could get a Guiness in the hereafter. Such is the infatuation of devotees of the thick and foamy beverage brewed in Ireland and sold around the world.

    In San Diego, this is a big month for Guiness and the 200 bars and restaurants offering it on tap. Courtesy of Coast Distributing Co., locals will quaff 97,000 pints of the bitter brew, much of it on St. Patrick's Day, March 17, paying $3.50 to $5 a glass for the privilege.

    "The amount of people that drink Guiness on St. Patrick's Day is amazing," says Katherine Bidenkap. "A bar will sell twice, maybe three times, as much as it will on a normal day."

     Bidenkap is the regional Guiness draught specialist for 600 bars and restaurants in Southern California. In essence, she teaches people how to pour beer.

    For starters, the ideal Guiness comes in a 20-ounce glass. "That is the traditional size," Bidenkap says. "We call it an Imperial Pint. It gives a beautiful presentation. Most bars do it in a 16-ounce glass. I try and help them dispense it maybe in a slightly different way and show them that the presentation is possibly a better way to sell beer. Just like you eat with your eyes, you drink with your eyes, too."

    And none of this sticking the glass under a tapper, giving a tug and walking away. No, a two-part pour is mandatory, she says, with the glass held at a 45-degree angle until three-quarters full. Then you let the beer settle completely before topping it off so the head rises just above the rim. If you pour it wrong, well, "there is not the same bitterness," Bidenkap says.

    When a bartender pulled out a frozen glass to demonstrate his pouring style, he got a lesson from Bidenkap instead. "Guiness needs to be poured in a room-temperature glass," she says. "In a chilled glass, as soon as it hits room temperature, condensation occurs. So as you start to put the Guiness in the glass, it doesn’t get as thick and creamy as it should. It also diminishes the head size."

    It’s not just enough to use a clean, dry glass held at the proper angle. The keg has to be pressurized at 30 to 40 pounds per square inch, as opposed to the 12 to 13 pounds of pressure used to push most beers. The mixture of nitrogen (75 percent) and carbon dioxide (25 percent) also must be correct. "Gas companies have been great in working with us to get that right mixture," she says. The 20-ounce cans of Guiness sold at liquor and grocery stores have a gadget in the bottom that releases the gas when the top is popped. Bottled Guiness is a completely different beer.

    While Guiness' thickness makes it look fattening, the alcohol content is fairly low 4.2 percent and the 10 calories per fluid ounce about the same as skim milk (not that many people would sit down and pound two or three glasses of skim milk).

    Patrick's II in the Gaslamp Quarter expects to sell a lot of Guiness on St. Patrick's Day, says bartender Barney Plomatos, especially during the block party that will see F Street closed between Fourth and Fifth avenues from 5 to 11 p.m. What’s Plomatos' method for serving Guiness? "Just hit the tap and pour," he says.

    Fraser Cathie, owner of Shakespeare's on India Street, also expects his business to dispense its share of Guiness on March 17. "People who have not drank it before, Americans I’m talking about here, will just get in a party mode and try it just to try it out. Consequently, we’ll sell barrel after barrel of the stuff."