In the mid-1920s, these women were the equivalent of today's circuit board builders. Called "coil winders," they worked winding transformer coils for radios in a Philadelphia factory. Featured on the Shorpy blog, this image gives us a glimpse of old-school tech at the moment when it was most cutting edge. Says one of the commenters on Shorpy:

This picture is taken in Atwater Kent's bright new factory on Wissahickon Avenue. Built in mid-1924 at a cost of $2 million, it originally covered 5 acres and eventually covered 32. You can see how fresh and unscarred the tops of the assembly benches are in this excellent picture, taken less than a year after this huge factory opened.

A little over ten years earlier in 1912, women's work looked a lot more old fashioned. Shorpy has this great image of office life at that time, in what the photographer termed the "government printing office, Washington." The contrast is astounding.

Radio Girl [via Shorpy] Government Office [via Shorpy]