Every day, "the horse" leads 260 or so men and women, mostly in their late 20s or early 30s, up the concrete path to a dirty brown, brick schoolhouse at 14th and Q streets NW not far from downtown Washington.

There, an increasing number of people daily receive a pain-killing drink that temporarily wards off the physical -- if not the mental -- stress of drug addiction.

"Horse" is street talk for heroin. The "schoolhouse" is a city-operated narcotics treatment facility that serves addicts along the 14th street corridor, known for prostitution, drug abuse and, most recently, the shooting death of a District of Columbia police officer.

Despite an intensive and continuing police crackdown on drug traffic that began in the area about six months ago, the number of addicts seeking treatment at this clinic has increased almost 30 percent.

The clinic now provides legal doses of methadone, an addictive substitute for heroin, to 260 people every day to keep them out of the drug traffic and related crime on the streets.

That number is up from 170 only six months ago. There are nine other such drug treatment centers around the city, now serving 2,000 addicts daily; a year ago the figure was 1,400.

A woman wearing a dress hat, short length fur coat, beige business dress and high-heeled shoes -- perhaps on a lunch break -- enters and walks past a man leaning against the wall who epitomizes the stereotype of the junkie -- tattered clothing, foul smell and a blank stare into nowhere. The woman passes another woman in too-tight jeans, presumably a prostitute, without a glance. All of them are junkies.

At the drug treatment facility, the signs of increasing drug addiction problems in the city are clear. Throughout the day, one by one, men and women amble up the sidewalk and enter the Barrett schoolhouse, more than a century old, shouldering symptons of anger, worry and despair.

There are those like Faith, 22, a Hagerstown native who arrived first in Alexandria to escape a boyfriend who beat her "every day for no reason. I learned after I lived with him he was mentally ill." Aimless, vulnerable and without money or family support, she turned to prostitution and then to heroin.

Or Marcie, 28, who after three years of study at the University of Wisconsin, won a scholarship and came to Georgetown University to become a nurse. One night, she said, she was raped. Frightened, angry and alone, a friend "who didn't know any better" offered her heroin. "Heroin helped me forget. It's the nicest feeling I know, but I don't recommend anyone trying it."

Louise, now 50, laughs when she remembers when she began riding the "horse" as a teen-ager. "I did it because of the men in the neighborhood that I admired, because they looked like they were living the good life, wearing fancy clothes, going to Atlantic City, and I wanted to be like them."

Officials said they see few young adult addicts. It takes awhile, they say, for the physical signs of addiction -- the itchy skin, the swollen flesh, the festering sores -- to drive the addict to seek help.

Drug addition has reached alarming levels in the District, according to police and drug treatment officials. Burglaries, larcenies and robberies -- all, to some degree, offshoots of narcotics problems -- were up significantly in 1979 compared to 1978.

Indicators that city medical officials use to gauge drug addiction levels also show an increase with no signs of significant decreases ahead.

At the drug center, addicts come daily for their methadone, standing at the glass-enclosesd counter with schedule card and color identification picture in hand. Through the glass window, they are handed the flower-printed paper cup of methadone that many swallow in one gulp, then swagger away.

They come to the center, medical officials say, when the street supply is periodically low or when police pressure becomes too intense. They stay in the maintenance program for as long as they like, then disappear into the streets.

It only takes one day for a physical checkup and paperwork to get on "maintenance" at one of three programs available. The others are detoxification -- a gradual decrease in dependency on drugs -- and abstinence.

Most of the 14th Street clinic's clients are enrolled in the maintenance program, some for as long as 10 years, others until the street supply is easily available, according to administrator Margie Truesdale. Follow-up is nearly impossible because many of those who enter the program give false addresses and phone numbers, officials said.

City Officials said about $4 million annually is spent on the drug-abuse program, an average of about $1,900 for every person enrolled in one of three programs. Nevertheless, the success rate is poor, officials said.

"What we are talking about is changing a person's life habits," said Truesdale, who began as police officer and has spent 25 years in law enforcement or drug treatment-related work.

"These people have severed family ties after years of being in trouble with the law, of begging money," she said. "Many of them have no marketable skills and no history of work. They have nowhere to turn except back into the street."

"This is a serious problem and there is no sign of it abating," said Kurt Brandt, medical director at the city's Substance Abuse Adminstration, a division of the Department of Human Resources.

"All of the indicators we use are up," said Brandt, ticking them off one by one on his fingers.

"Overdoses have jumped from 8 in 1978 to 41 in 1979. Emergency room cases involving overdoses have increased from 204 in 1978 to 316 in 1979. Street prices of heroin per milligram have dropped from $5.40 in 1978 to $2.44, while at the same time the purity of that heroin is up 50 percent. Regular admissions in our treatment program have increased from 2,239 in 1978 to 2,849 in 1979, while we have about a 30 percent increase in new admissions," he said.

"We've looked at the surveillance results at the D.C. Superior Courts and we find that urine samples of [those awaiting arraignment] show that evidence of narcotics [usage] is up from 17 percent in those tested in 1978 to 22 percent in 1979, and most of both year's samples involved the drug heroin," he said.

Gloria Hardy, a counselor at the clinic, sees the faces, not the statistics. A former-addict herself, who, after 10 years with the "horse" went cold turkey in 1968, she knows the people and the problems.

"Drugs are an escape from reality. It's a symptom of a much deeper problem," said Hardy, leaning back in a chair in her sparesely furnished cubicle. She cups her hands, which are still swollen and blotchy from collapsed veins after years of addiction.

"Other people find other ways to escape the pressure, but for many of these people, drugs is the way out from the conditions they live in, from low self-esteem after not having a job, or decent clothing or shelter," she said.

"When I go out there in the streets(among young folks) I see anger -- anger about a system that denies them what they see a lot of other people having," Hardy said. "Narcotics kill the pain of feeling that you've been dealt a bad card in the system. That goes for blacks, it goes for whites, it goes for anyone poor."