AFter the word public appeared here as "public," I recalled Bob Considine's Law on typographical errors: "Whenever one word or letter can change the meaning of a sentence, the probability of an error being made will be in direct proportion to the embarassment it will cause."

I was embarrassed because most District Line readers are aware that I have for many months been "setting the type" for this column by writing it on a video display terminal hooked into a computer. Seven readers immediately informed me that in my case Considine's Law didn't hold true. There is a more embarrassing way to misspell public . As I. H. Jurow of Chevy Chase put it:

"It must have given Justice Hugo Black no little embarrassment to read, in the June 8, 1965 issue of the United States Law Week, that his dissent in Cameron v Johnson quoted the relevant Mississippi statute as making it 'unlawful for any person to engage in picketing or mass demonstration in such amanner as to obstruct or interfere with free ingress and egress to and from any public premises.'"

However Trudy Hansen of Alexandria thinks Considine was right. Mrs. Hansen does a newsletter for the Salvation Army and "out of 55 issues I have done, I have yet to glance at a printed copy without having at least one error leap to my eye." In the latest issue, a note thanking Hexagon, Inc., for a gift of $1,050 turned into an embarrassment because one word was misspelled - Hexagon , of course.

Bob Donnelly of Arlington thinks artist Jeff MacNelly ought to be embarrassed by a goof in one of his recent "Shoe" comic strips. Jeff showed Shoe sealing his tax return and sending his check off in an envelope addressed, "IRS, Wash., D.C." Tax returns aren't sent to Washington.

Several readers have sent me clippings of a beauty shop's ads that advise the public (see, I can spell it right) where to find a certain hairdresser, "formally" connected with another shop.

However, my favorite ad of the week is one clipped by W. C. Lee Sr. of Bowie. It offers for sale a 1975 model Cherokee Chief that is fully equipped, including an "8,000-lb, wench."

I don't think I'll put in a bid. I can't even handle a little bitty 120-lb wife.