Time was when public transit in Washington meant horsepower. Stagecoaches carried travelers from Georgetown to Capitol Hill starting in 1800. Horse-drawn omnibuses owned by the Vanderwerken family had a monopoly in hauling riders over what passed for pavement from about 1844 onward. The city's first streetcar line, the Washington & Georgetown Railroad, began with horse-drawn cars in 1862, passing a White House occupied by Abraham Lincoln.

The last of Washington's horse cars halted on May 26, 1900, on the LeDroit Park line, replaced by electric streetcars.

Yesterday--would you believe: yesterday, Sept. 23, 1983?--the Washington Metropolitan Area Transit Commission got around to deciding officially that it does not have legal jurisdiction to regulate public transportation service provided by horse-drawn vehicles.

Strange as it seems, the matter is not frivolous. A bit of background: The transit commission once regulated D.C. Transit and other area bus systems. When Metro took those over, the commission was left with several residual chores, including the regulation of regional sight-seeing bus services.

Recently, an outfit called Old Vet Carriage Co. Inc., inquired whether it was required to get the same kind of approval from the commission to run a horse-drawn sight-seeing service that motorized operators are required to get.

Careful lawyer that he is, Gregory Paul Barth, the commission's general counsel, looked up precedents. And he found that in 1967, the commission decided officially that horse-drawn operations needed licenses. A potential applicant in that year decided, however, to back off from applying, and the issue remained dormant until Old Vet Carriage raised its recent inquiry.

In a unanimous decision, the commission decided yesterday that "horse-drawn vehicles are nostalgic memories . . . no longer a mode of public transit," and agreed to exempt them.