In an era of credit card calculators, it's hard to imagine trying to figure the interest on your savings account via a wrought-iron drum with knobs.

But Pleasant Grove native Kay L. Jacobs, now president of Deseret Bankcorp, can still spin out a calculation on such a device, which has been recently donated to Brigham Young University's repository of historical accounting instruments.The massive calculator, used at the bank until 1954, is "very easy to use," explains Jacobs. "It only takes about 15 to 20 minutes to become familiar with it, if you have a little math background, of course."

Shaped like a long cylinder with a calculating table printed on the surface of an inner drum, the calculator was produced and patented by the Meilicke Calculator Co. of Chicago, Ill., in the early 1900s.

By manipulating a wheel on either side of the device - which positions the date and month - the exact accumulated interest charge can be calculated by checking the interest rate chart printed above a series of numbers.

While interest on savings accounts during the 1940s hovered around 1 or 2 percent, interest on bank loans was considerably higher, ranging between 6 and 10 percent, Jacobs says.

Solid-looking and rather elegant with its black veneer, large, adjustable magnifying glass and trim detailing (complete with a painting of a bald eagle), the calculator is a valuable addition to BYU's growing collection, says Norman E. Wright, a BYU professor of computer science.

"This drum calculator represents a very clever counting device,"

says Wright, a self-driven historian who loves to ferret out such hidden treasures.

Wright and Jacobs, in fact, were childhood buddies whose fathers co-managed a Pleasant Grove canning company at one time. The fact that Wright was gathering historical counting devices for BYU made Jacobs feel that the bank's cherished piece of history would stay in the family.

Even though progress in the form of electric adding machines, calculators and computers eventually replaced the cumbersome instrument at the bank, Jacobs doesn't quite harbor the same affection for the more modern devices.

"I've kept this calculator around for years because I thought there might be a time when someone else would appreciate it," says Jacobs, who started out at the bank in 1946 as a teller and eventually moved through the ranks to become president. "People here developed an attachment to it. Especially me."