Clack, clack, clack ...

The metallic ring of a hammer pounding in a spile, or maple sugar tap, echoed through the woods Friday morning, and I held my breath for a moment.

Sure enough, a miracle: A single drop of sap grudgingly appeared on the spout. An hour or so later about a cup of the clear liquid collected in a plastic jug.

"Spring is upon us! " I cried.

"Great!" Steve Kurczy, a friend visiting from Bueonos Aires by way of Woodstock, Conn., replied.

Having endured such a relentlessly frigid winter we all need some reassurance that days of warm sunshine eventually will return. Some rely on the first sighting of a robin; others welcome crocuses and skunk cabbage poking through the snow; others await the arrival of pitchers and catchers at baseball's spring training; meteorological sticklers insist on holding out until the official vernal equinox that occurs this year precisely at 12:57 p.m. EDT March 20.

For the last several years, as loyal readers and viewers of The Day's videos may recall, my most reliable spring indicator has been sap flowing from the maples.

Historians credit Native Americans with discovering that sap can be converted to syrup by allowing it to freeze and removing the ice. Colonists later perfected the operation by boiling saps in kettles.

Though modern producers string miles of plastic tubing between tapped trees and then employ sophisticated reverse-osmosis technology and hydrometers to remove water and measure sugar content, my system hasn't evolved much from centuries-old practices: I drill holes in maples, pound in taps, collect sap in gallon jugs that hang below the spigots, and then, using a makeshift fire pit behind our house, boil the clear liquid for hours until it turns a rich brown.

Regardless of which method you use, it still takes about 40 gallons of sap to make one gallon of syrup.

I customarily tap about 20 trees and in good years have been rewarded with a gallon or so of syrup — much of which friends and I immediately consume at the fire over pancakes cooked on a cast iron skillet topped with ice cream, or, for health fanatics, over Greek yogurt.

Because this season has gotten off to such a late start I don't have high hopes for a bumper yield, but I'm hoping quality compensates for what may be lacking in quantity.

For the last several weeks I've been monitoring the outdoor thermometer closely, waiting for the right conditions to tap. You need cold nights followed by warm days, but until late in the week we've had nothing but freezing temperatures 24/7.

Steve, eager to gain insights into the maple operation, came over to help.

In past years the sap started flowing as if from a faucet, but not so this season.

"It's a leap of faith," I explained.

It's also a question of timing: You can't tap trees too soon or you'll get nothing but sawdust from the hole drilled into the tree; if you tap too late in spring maples produce bud sap that after boiling down tastes more like like Palmolive dish detergent than something you want to serve with pancakes.

I hope to start boiling in about a week.

The key is to remove just enough water to sweeten the liquid — but if you let the kettle boil too long the sap can disintegrate to ashes in a heartbeat. A couple years ago I rescued one batch just in the nick of time. It had started to carmelize and turned into a kind of maple crème brule — a feat I could never repeat in a millennium of maple syrup production.

Anyway, I'm thrilled that my spring has finally arrived. It's been a bitter winter; we all deserve something sweet.