When Carlyle Peterson opened his structural engineering office in the Insurance Exchange Building in downtown Des Moines in 1952, long-sleeved white shirts and neckties were the typical attire. Coat and tie remained so for many years, and for him even into his 90’s before he retired and moved to Sun CIty, Arizona. Slide rules were used for structural design calculations, even after the first electric mechanical calculators were acquired. Carlyle became known for always being on the cutting edge of new technological developments in that arena. The Monroe mechanical calculator, Frieden 4-line CRT electonic desktop calculator with memory, later more sophisticated calculators, and eventually a room-sized IBM 1130 computer with 8K core, removable 512K storage disks, punch card input and line printer required an addition to the Peterson and Appell office building at 5615 Hickman Road in Des Moines, not long after they first moved in from their second office location on Polk Boulevard. This computer was kept in use for 25 years, and proved to be an invaluable engineering tool.

Design of a large variety of buildings for a number of different architectural firms across the state required increasing staff size in the 1960’s, but conditions later dictated scaling back after Don Appell left the practice in 1972. This was done by attrition, rather than abrupt reduction by dismissal. A number of those who left became direct competitors, but they left well-trained for the most part.

Drafting was done manually with tee squares, triangles and mechanical pencils, later parallel rules on larger drafting boards, using mylar film instead of clearprint tracing paper. The decision to go to computer drafting was only made when it became possible to make computer drawings look as good as manual drafting. The development of the ink-jet plotter aided in that decision, as pen plotters were deemed to be too bothersome.

In the 1960’s the firm provided consulting structural engineering to Fair-Play Scoreboards of Des Moines for installation and support of scoreboards in baseball parks around the country.

Scoreboard support frames were designed for Indiana University and Drake University in 1960, Dodger Stadium in Los Angeles in 1961, Municipal Stadium in Philadelphia and Mets Scoreboard in 1962, Lamar Scoreboard in Beaumont, Texas in 1963, the Astrodome in Houston in 1964, Veterans Memorial Auditorium in Des Moines in 1965, Busch Stadium in St. Louis in 1966, University of Illinois in 1968, Truman Stadium in Kansas City in 1970 and Texas Stadium in 1972.

In 1968 Peterson & Appell moved into a new office building that they designed. This provided a custom designed space with ideal north light for the drafting room in the main north wing, and office space for the principals and receptionist under the folded plate roof south of the west main entrance. This building has been owned and occupied by Camp Fire since 1979, as Peterson Engineers no longer required that much space and moved to Valley Square at 974 - 73rd Street, and to an office space in West Towers at 1200 Valley West Drive, West Des Moines from 2000. - 2025 and NOW LOCATED AT 3524 ELM STREET, WEST DES MOINES, IA 50265