In yesterday's column, we declaimed about the problems of Arlington's chaotic and too often disconnected street network. Although the District of Columbia sometimes produces problems for visitors, its network, by contrast, is organized and relatively easy to comprehend.

Longtime Washingtonian Shari Kharasch says few people today seem to appreciate the concept of the "four alphabets" for east-west streets. She's right in asserting that it should be more widely recognized.

Moving northward (or southward) from downtown, the "first alphabet" is letters. Going northward in the Northwest quadrant, they run from C Street through W Street. Lower-lettered streets generally would be in the middle of the Mall. (In the Northeast, with no Mall, they start with A Street.) The "second alphabet" is two-syllable names in generally alphabetical order: Hobart, Irving and Kenyon, for example. The "third alphabet" is three-syllable names, also in alphabetical order: Albemarle, Butterworth and Cumberland, for starters. The "fourth alphabet," east of Rock Creek Park, is horticultural names, also in alphabetical order: Floral, Geranium and Hemlock are examples.

There are, of course, interruptions to the pattern. "Roads" -- Columbia and Military are examples -- are interspersed among the streets.

Why do the lettered streets northward from downtown end with W Street? There's a good reason, which was logical in the last century but makes little sense in 1984. Do you know it?