Patrick Skene Catling is working in his 14th book, a novel abut jazz.

Saint Patrick drove the snakes out of Ireland, it is said (in Ireland) and they reappeared on Third Avenue, New York.

Well, okay. But that doesn't really quite account for all those astonishing shades of green that were sashaying around here yesterday.

The Irish embassy sent Barbara Edmondson to Capitol Hill early in the morning with a load of genuine Irish shamrock, which had been flown in by Aer Lingus last Friday. The shamrock, of course, was limp. But the limpness did not matter. The Irishness was what mattered.

The magic worked. Washington yesterday was Irish. No other alien ethnicity is so potent. What color would you expect publicans to dye the beer for the patron saints of, say, Czechoslovakia, Taiwan, Peru?

Green, of course, is Mother of Nature's very own spring color, for heaven's sake. The weeping willows were ready just in time.

I did my best.I wore a bottle-green jacket that Abercrombie's gave me free on condition that I would never flash the label in Southampton. Mossgreen socks and a bile-green pocket handkerchief, if you'll allow some St. Patrick's Day J.P. Donleavy syntax. A chartreuse-green tie.

A sympathetic Connecticut Avenue sidewalk florist was kind enough to let me have a Kelly-green carnation for 50 cents. I gave it to Edmondson for some of the real stuff. (Would you have loved it more, Edmondson, if it had cost a dollar? I hope not. I think not.)

I thought I was wearing green, until I saw some of the Washington greens. I saw som green slacks that would have looked gaudy on a golf course in Palm Springs. I saw a dress to brilliantly LSD that I was unable to resist screaming congratulations from the cab. "That is GREEN!" I screamed, and the wearer prettily dimpled, allowing as it was.

I had an Irish story with me, fresh from Dublin - not very fresh, but fresh enough. I took it to Ellen Donlan's Irish Pub on Connecticut Avenue and gave it to the darling lady, herself, in person, in exchange for an Irish breakfast. Breakfast is the best Irish meal. It is served in Ireland three times a day, if you're lucky.

The story went as follows:

Stranger to Dubliner:

"Tell me, is there an Irish word equivalent to the Spanish work manana?"

Dubliner:

No. Nothing that urgent"

Needless to say, the ham and eggs were better, but Ellen was in a holiday mood and forgave me, or seemed to.

Ellen sent me to St. Mattew's Cathedral and I thanked her and God for getting the day off to such a grand start.

Ted Smith, the press officer at the Irish embassy, said he had expected to be "the top shamrock in Baton Rouge" until it became apparent that the ambassador, John G. Molloy, would require his attendance on the Irish Foreign Minister Dr. Garret FitzGerald, whose visit to Washington happened to coincide with St. Patrick's.

Smith consoled himself with the happy thought that he would be required also to attend the annual banquet of the Friendly Sons of St. Patrick.

"Gerry Cassidy, the president of the Friendly Sons, will be there," he said. "So with Hal Roach, the comedian." I tried to reach Cassidy at his office. His secretary said he was out to his St. Patrick's Day lunch and would not be back for 24 hours.

That is what St. Patrick's Day lunches were like. I tried and failed to have corned beef and cabbage at the Dubliner, which was a crowded and as happily chaotic as a Rugby Club after a good afternoon. One of the customers was rewarded for Irishness when he ordered a whiskey in Gaelic. The bartender filled a tumber with the Paddy then, didn't he?

I, myself, scored a few points by paying for a bottle of Harp with an Irish 10-pound note. I thought the bartender was accepting it with Irish love. He was. He gave me $1.69 to the darling pound.

Matt Kane's place was equally active but he didn't seem particularly thrilled by the crowd it had attracted.

A County Mayo man from Chicago, friend of Presidents and many others, Kane said:

"This is the day of the amateur drinkers."

He was right.

I was full up to here with Irishness, so I went to The Clas Reunion, where out-of-work Republicans go to cry.

It is one of Washington's fine nostalgia bars. But yesterday, instead of music by Glenn Miller, there were Irish jogs.

"Is it the Aer Lingus office you're looking for then/" asked a man with a green carnation.

"It is," I said. Now that Fitzgerald's here, there must be some nice quiet music in Dublin.