If you're restless this weekend, try inventing something. In fact, try doing it Saturday, which is the anniversary of the first U.S. patent (July 31, 1790).

The first patentee, Samuel Hopkins of Vermont, was very like the millions who would follow in his footsteps: average and largely obscure. His invention for making "pot and pearl ashes" (potash) made a big hit where it counted -- with the patent board, which was composed of Secretary of State Thomas Jefferson, the secretary of war and the attorney general.

The process of securing a patent then was rigorous, but it was also democratic -- first come, first served -- and absolutely essential to the nation's industrial development. The procedure was uniform among the states, thanks to a constitutional provision empowering Congress "to promote the progress of science and the useful arts by securing for limited times to authors and inventors, the exclusive rights to their respective writings and discoveries."

The process was also cheap: four or five bucks secured a patent. The cost has remained within the average person's grasp, although the Patent and Trademark Office has recently proposed fees that would make it cost more than $5,000 to obtain and maintain a 17-year patent.

The history of the patent office has sometimes been as dramatic as the inventions it has patented. For example, the first patent law passed in 1790 was revised three years later, making it easy -- much too easy -- to register a patent. In place of scrutiny by a board of examiners, a system was introduced whereby each inventor swore to the utility and novelty of the claim and simply paid a fee. Then the real fight between inventors took place in the courts.

In those early years, the patent office was bureaucratically situated in the Department of State. But its actual location was four rooms in Blodgett's hotel (E Street, between Seventh and Eighth streets), where confusion abounded, what with guests, inventors, and sly-by-nighters. The first commissioner, Dr. William Thornton, tried to keep on top on things, but the traffic was heavy and assistants were few.

Then came the War of 1812, when the British marched on Washington and threatened to put a torch to the hotel. Dr. Thornton, a learned physician who had a way with words (including a published treatise "On the Elements of Written Language"), shamed them: "This is the Emporium of the Arts and Sciences of America," he scolded. "Don't burn it. If you must, let the first shot pass through me." To the surprise of everyone save Dr. Thornton, the building was spared. Congress even met there for a time while the war- ravaged Capitol was being renovated. Unfortunately, what the British didn't set aflame became a towering inferno in 1836 when fuel stored in the basement caught fire. Everything went up in smoke.

No matter. Congress had already decided to provide funds for a new building and to revise regulations to ensure scrutiny of each application -- much in line with today's procedure. The legislation paid off in more ways than one: the allegedly fireproof patent office became the repository of the Declaration of Independence from 1840 to 1876. The new office also became the National Museum for the models of inventions that were required by the 1836 law.

So inundated was the office by the rising tide of American inventive genius that it was forced to tranfer some of its model collection to the Smithsonian Institution after its founding in 1846.

By the latter part of the 19th century, the patent office -- after surviving another serious fire -- was lodged in the Department of Interior, where it occupied 99 of the 252 rooms. Although some household names would emerge from the office's records by the early 20th century -- Isaac Singer and Thomas Alva Edisonia, for instance -- thousands of " little" people were anonymously making their mark on the nation's economic development. According to the patent office's 1923 annual report: ". . . there were filed 80,522 applications for patents as well as 16,817 applications for the registration of trademarks, and there are now over 200,000 applications pending. . ."

By the time it moved in 1925 to its present lodging in the Commerce Department, the office had already issued the millionth patent. The second million was reached in 1935, the third in 1961. The current number is approaching 4.5 million.

Prospective inventors should pay a visit to the Patent and Trademark Office before formalizing their inventive genius. Until the late 1960s, the breathtaking starting point for this venture was the huge and magnificently ornate public search room in the Commerce Building. Today, the search room -- as well as much of the patent office -- is located in Crystal City. But the process is much the same as it has been since 1836: search the records, which are catalogued according to subject matter, to ensure the novelty of your idea; make application; submit drawings; pay fees; and take an oath. And then wait.