Frederick Tilp's book is like one of those sturdily built great schooners he describes that sailed the Potomac a century ago loaded with every imaginable local cargo.

Solidly packed into his 35 chapters is the varied and abundant history of the river, its lore and its legends, gathered and recorded with infectious enthusiasm by a waterman who has known the Potomac for 60 years and has "witnessed the panorama of sailing craft, steamboats, shipyards, lighthouse keepers, fishermen, oystermen; yes, even the gamblers, rum-runners, and prostitutes."

The author, an architect by profession but one with a love of the river that led him to limit his shoreside practice to buildings almost in sight of the water, has sailed it would seem every cove and inlet of the tidewater river, talked at one time or another with everyone with memories of an earlier day and remembered everything he has learned. More, he has explored equally thoroughly the holdings of libraries and archives and old newspapers that might yield cargo for his book.

His more than 300 large double-column pages of text, with a small library of rare photographs, can be intimidating as well as inviting and it is well to take the author's advice that "each chapter is complete in itself" and the reader "may start and stop at any point without concern for continuity."

The best strategy for a reviewer, as Randall Jarrell once said when faced with the poetry of Marianne Moore, may be "to go though the book pointing."

Are you a Civil War buff? The comprehensive chapter on "Palasades, Forts, and Wars" will make the book an indispensable one for you and you will get a bonus chapter on John Wilkes Booth.

Are you a gourmet? Then turn first to the chapter "Stuffed Ham and Ice Cream." If it does not finally settle the question of the only proper way to prepare stuffed ham, it does provide the principal contending recipes.

Are you fascinated by marine disasters? There have been enough tragic collisions and fires and explosions on the Potomac to make a long and somber chapter here.

Do you know the difference between a barge, pinnace, shallop, wherry, canoe, skiff, doryboat, sharpie, sturgeon skiff, sloop, yawl boat, schooner, lumber schooner, pungyboat, brogan and bugeye, skip-jack, ram, longboat, fish lighter, shad galley and xebec? If not, you will find them all, with drawings of most, in "Sailing and Rowing Craft." (The xebec, a favorite vessel for the early slave trade on the Potomac, strongly influenced the design of all river and Bay sailing craft.)

A chapter of "River Towns" provides admirable succinct sketches of Accotink, Aire, Alexandria, Bladensburg, Colchester, Colonial Beach, Dumfries, Georgetown, Jackson City, Kinsale, Leonardtown, Marlborough, Matildaville, Occoquan, Piscataway, Port Tobacco, Saint Mary's City and not least Washington.

The opening chapters of the book are on "Indians" and "Early Explorers" and "The Tobacco Society," and these three are followed by two chapters that chronicle what unhappily is now almost equally ancient history: "Fisheries" and "Sturgeon and Terrapin." Tilp notes soberly that we have "plundered and ravaged the nation's finest equipped estuary of profitable production of seafood."

In the space at hand I can only list some of the remaining chapters that I have found of most interest: "Lightships and Lighthouses," "Floods and Ice Gorges," "Bridges," "Roads, Taverns, and Ferries," "Canals and Railroads" and "Riverside Stores."

Mr. Tilp writes at the outset: "The Potomac River and its beauty may be truly known only by those who sail from the head of tidewater along the winding reaches, into every estuary to the Bay. Viewing the river by automobile, aircraft, power vessel, large sailing ship or while sitting in a comfortable room reading this book will not give the true feeling of the river. A slow cruise in a slow cruising sailboat is an absolute requirement, and cruising simply means sailing to a particular place you want to see or explore, rather than just sailing aimlessly."

This may be true but Mr. Tilp is too modest. No cruise on the Potomac today, however purposeful, could provide the voyage through time that "This Was Potomac River" so admirably presents.