Herbert Butler, 72, is a retired telephone company employe who lives in the split-level house in South Arlington "100 feet from Shirley Highway" that he bought 16 years ago for $37,000.

Since then Butler, like homeowners throughout the metropolitan area, has watched his assessment and real estate tax payments climb steadily as the value of his house has more than tripled. Last weekend he learned that the assessment on his three-bedroom home rose another 18 percent over last year and will face a property tax bill of nearly $1,800.

"My taxes will exceed my mortgage payments," Butler told the Arlington County Board Tuesday night at a hearing on the 1978 real estate tax rate. "In effect the county has confiscated my property and now lets me live there for the same amount as I pay the banker."

Butler was one of nearly 150 Arlington residents, many of them older citizens on fixed incomes, who jammed the acrimonious four-hour public hearing on the real estate tax rate to protest what one woman called "these wildcat increases in assessments." Arlingtonians received their assessments beginning last weekend.

Despite repeated statements by County Board members that the board legally could only retain or lower the real estate tax rate of $1.49 for each $100 of assessed value, most of the speakers bitterly insisted that the board could reduce their assessments.

The board voted 3 to 2 Tuesday not to change the rate, although it may decide to reduce it when it adopts a budget that will run from July 1 through June 30, 1979.

Assessments are made by county employees who through visits to property and studies of sales records compute the assessment for the full value of each house as of Jan. 1 each year. The County Board, which is legally barred from interferring with assessments can change only the tax rate.

"This is a very technical field and we have relied on the county manager to hire technically competent people," said County Board Chairman John W. Purdy, noting that homeowners can appeal assessments to a special panel of homeowners. His statements were met with jeers and groans of disbelief.

Early in the hearing board member Joseph S. Wholey leaned forward from the dais and patiently addressed the group. "Are people in this room aware that the value of single family homes has been rising by 10 percent each year? If people don't like the (increase) they . . . should ask us to lower the tax rate. That's what this hearing is about."

When one man complained that his house was assessed at $107,000, Purdy asked him the selling price for comparable homes in his neighborhood. "Oh, I could get $125,000 for my house," the man said confidently.

When another speaker said he believed that the board could do something about his assessment, Wholey angrily said, "You wouldn't like to live in a county where the County Board could lean on the assessor to lower assessments" or grant similar favors.

Victor Lloyd, a PTA president, was one of three speakers who urged the board not to adopt a lower tax rate. "My assessment went way the hell up but if it's a choice between higher assessments and (cutting) services, then we have to go with higher assessments," he said.

A motion supported by conservative board members Dorothy T. Grotos and Walter L. Frankland Jr. to cut the rate 9 cents per $100 of assessed value was defeated 3 to 2 when Wholey, a fiscal conservative, failed to support it.

Wholey, who exerts great influence on Arlington's budget, hinted that he would rather wait until after consideration of the upcoming budget before possibly changing the tax rate. One high-ranking county officials speculated that, the board might then vote to cut the tax rate by 3 or 4 cents.