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.