July 27, 1986

It is a long, hot summer in New York for David Letterman. First, there is the problem of the Nielsen ratings - they've never been higher. ''It's like a tap on the shoulder from some ominous unknown force,'' said Mr. Letterman the other night after the 5:30 P.M. taping of NBC's ''Late Night With David Letterman'' in studio 8H in the RCA Building, where Toscanini once conducted. ''It's like a warning that I've got to do better, and keep doing better, or the ratings will go down and I'll be left a lonely broken shell of a human - like I am now.'' Then there is the Emmy Award problem: NBC has already announced that Mr. Letterman will be the co-host of the Emmy ceremonies on Sept. 21. ''The way I look at it, they have till mid-September to find someone else for the Emmy deal,'' said Mr. Letterman. ''I'm especially afraid that they'll want me to sing and dance in a large group of people.'' Even more troublesome are the four television specials that NBC has announced he'll be doing next year: ''I hope we don't have to do a one of them,'' Mr. Letterman said. ''I mean, we have our hands full just keeping this thing going every night.''

''A songwriting partnership is like a marriage,'' Richard Rodgers wrote. ''Apart from just liking each other, a lyricist and a composer should be able to spend long periods of time together - around the clock if need be - without getting on each other's nerves. Their goals, outlooks and basic philosophies should be similar, so that the song they create is accepted as a spontaneous emotional expression emanating from a single source.'' Rodgers's comparison of songwriting collaboration to marriage is one of those cliches that happens to be profoundly apt. But while it applies as much today to Broadway collaboration as it did 30 years ago during the golden age of the Broadway musical, the ethics and expectations of theater songwriting, like the institution of marriage itself, have changed and relaxed. It now costs about $4 million to mount a typical Broadway show, and the process of investment and development usually takes several years. Ambitious songwriters have to scramble to become involved in the few projects that eventually get produced on Broadway. And with so much riding on each show, their collaborations tend increasingly to be short-term affairs tailored to specific projects.

It's no secret to say that drama is a restrictive medium, and that those of us who try to write plays are hedged in on all sides by tough laws of dramaturgy which we break only at our peril. To compound the problem, American playwrights, dependent as we are on the uneasy generosity of private enterprise, would seem to be even further encumbered by economic inhibitions that require us to be downright miserly about the number of characters we use or the settings in which our plays take place. Of course, all playwrights everywhere have long been used to dancing in various chains. Aeschylus was bound by the ritual rule that only two characters on stage at one time were allowed to exchange dialogue. Moliere had to be scrupulously tactful about church and court under the shadow of Louis XIV. Samuel Beckett embraces and makes a virtue of the very spareness which good contemporary drama is asked to impose upon itself.

''This isn't a drought,'' Ray Ward, a Georgia dairy farmer, said one day last week. ''It's not even a disaster. It's a catastrophe.''

BEFORE New York's office economy grew as burly as it is today, financial institutions often required developers to have anchor tenants in place before they would write a construction loan for a major new office tower. In the current market, however, an unusual number of major buildings have been started by financially strong development companies without any tenant commitments at all. Perhaps the most notable was 7 World Trade Center, a 47-story, 1.9 million-square-foot office building begun a year ago by Silverstein Properties with no tenant commitment. Drexel Burnham Lambert, the investment house, agreed only two months ago to take an equity interest in the project and also lease the entire building for 30 years. Other major office buildings that have started without major tenants include Olympia & York's 607,000-square-foot building at 425 Lexington Avenue, at 44th Street; Madison Equities's 400,000-square-foot building at 135 East 57th Street, at Lexington Avenue, and a William Kaufman Organization building at 17 State Street near the Battery with 525,000 square feet of space.