ESU legs and knobs/pulls  

My 2 Cents
The original ESUs, designed in 1950, had legs that were integral to the structure -- i.e., like the current reproductions. These are called the "first series" ESUs.
In about 1952, I think, the legs were changed to the tubular ones with the triangular supports -- these are the "2nd series" ESUs. The legs were no longer integral to the structure of the piece, and were moved "in" toward the middle part of the unit. This was done because of a structural problem with the 1st series -- the legs on those were frequently bent during shipping, and proved somewhat unstable as well. On many 1st series ESUs one sees these days, e.g., the legs are bent inward.
The 2nd Series also brought about a change in the pulls and contained visibly dovetailed drawers. Why this occurred I don't know.
ESU production ceased in 1955. I think the repros by Modernica, and then by HM, started in the early to mid 1990s.
In sum, the current repros resemble the 1st series. Maybe HM has strengthened the material or something, I don't know.
P.S. From the collector's perspective, my sense is that the 1st series, because of their greater age and rarity, were initially favored. However, most agree that the 2nd series units are actually more attractive. And I'm told that, these days, those forking over their big bucks for vintage ESUs prefer the 2nd Series.

That's Strange
Thanks for the info. I had always assumed that the 2nd series was the first series. I guess because I prefer the (real) 1st series I thought it was second, since in my mind it was an improvement. However, in thinking about it further I would rather know that the 'better' design was first. The model with the integral legs seem more eamesian to me, being that the design seems to flow together wholistically. The 2nd series, while I still think it is attractive and a nice design, doesn't contain the same continuity. I think the pulls and integral legs blend with the design better than the recessed legs and the knobs. It acually comes as a suprise to me that the 2nd series is preferred aesthetically .... functionally I can understand.
Most design changes based on manufacturing functionality that I am aware of was made internally at Herman Miller, perhaps with Charles' permission. I wonder about this instance. I wonder why the pulls were changed to knobs at the same time. Could it be that the new legs were viewed as a fugitive element and it was believed to need another fugitive element to balance it out? Perhaps I am the only one that sees the knobs as a fugitive element .... I don't know.