James,
Many thanks for your most helpful and informative response to my question regarding cage filament supports. Before posting this question, I had searched Howell & Schroeder, but even though there is a wealth of detail on development of bulb manufacturing techniques, I could find nothing on this admittedly somewhat obscure aspect of early tungsten bulbs.
Shortly after I posted this question, I saw a Mazda on e-bay with the thick copper supports and bid on it. After it arrived, I observed other features in addition to the copper supports that seemed to indicate an early manufacture - the welded lead-ins going through the stem press, and the attachment of the filament to the leads using the earlier crimped tubes as opposed to the simplified "hook" connection. From this, I deduced that probably the copper supports are a sign of earlier lamps. So it was nice to have your confirmation of this as well as the other details which I am pleased to learn about. Again, thanks for answering.
PCris