The dean of writing at Cornell University is in hot water for the most embarrassing of reasons: people are saying he doesn't write very well.

To make matters worse, Robert Farrell, who heads a $1-million-a-year campus "war on illiteracy," appears to have written the brief for the prosecution. It came last week in the form of a letter to the Cornell Daily Sun.

The letter was meant to be Farrell's defense against attacks on the writing program from the student newspaper and some history professors.

Whatever the merits of Farrell's case, the letter left more than a few red faces on the Ithaca, N.Y., campus. Farrell's opponents charge it "is the most spectacular illustration of the weaknesses the 'war on illiteracy' was supposed to combat." And even his supporters acknowledge the letter is awkwardly worded and contains more than a few grammatical errors.

The harshest blow came from a young Cornell alumnus who alleged that the letter contains "no less than six outright, palpable, indefensible grammatical or technical errors" - in the first paragraph.

"Mr. Farrell does not write as well as the average Cornell freshman," wrote Daniel Margulis, a technical adviser to the student paper. "His knowledge of the rules of grammar and syntax is rudimentary. His vocabularly is so limited that he is frequently unable to express his thoughts for want of a precise word or phrase . . . Worse, he is verbose and redundant."

To be fair, a number of errors in Farrell's letter are minor ones and might have been overlooked had they been made by anyone but a dean of writing. Twice he used unnecessary adjectives, saying, for example, "rigid constraints," which is redundant because constraints are rigid by definition.

But he also made several serious, basic errors. He used, for example, "are" instead of "is" in one sentence. He mixed a cliche by trying to "set the record clear" instead of the more conventional "Set the record straight." He wrote the following run-on sentence: "At no time did I approach the provost directly, since it is not my place to do so; I report to the dean, he carries affairs as he will from that point."

In addition, some of his sentence structure is confusing and almost impossible to follow. For example, he wrote: "I had communicated with Dean Levin on the general problem several times, starting last spring, and the second, that of over acceptance came to me in late August."

Farrell dismissed the letter as a "rather nasty" example of grammatical nitpicking.

"What we have here is a student newspaper looking for a story to start off the fall," he said. Academic politics was also at play, he added. "There is a tension in the university between traditional allocations of money and anything that is new," he said.

It is true that Farrell has enemies on campus. They've accused him of everything from empire building and inept management to advocating a "soft-line" approach to improving student writing.

"There's a lot wrong with him," declares history professor L. Pearce Williams, Farrell's most outspoken critic. "He's incompetent to run a writing program. Basically, he's not a very good writer; he has a tendency to be overbearing. The letter showed a complete lack of talent."

Williams advocates a hard-line approach to student writing.

"My method is the same as that used by the Marine Corps. I take freshman apart and then put them back together as literates," he once explained. "You might say I destroy them. I am a believer in the total assault concept."

Farrell, believed to be the nation's only "dean of writing," advocates a more gradual, confidence-building approach, which has had it opponents ever since he was named to the post last winter.

But the stakes escalated during freshman registration for the fall when a dispute developed between Farrell and the history department over who would teach writing seminars in a class on Western civilization. A number of history department professors called for Farrell's removal for alleged administrative blunders.

Arts College Dean Harry Levins refused to remove Farrell, but he did strip him of much of his power to establish how and by whom writing would be taught at Cornell. Levins gave control to a blue-ribbon faculty committee.