The rectangular sense core wiring is I believe limited to 1024 cores. Diagonal sense (with a diagonal wire axis) replaced it. Click image for larger view.

Not sure the date of this core, it could have been made in the early 1950's but there is no way to know yet for sure. What computer used this kind of core? The use of diagonal sense core became the standard by 1955. Maybe this was an experiemental core for some engineering purpose. Click image for larger view.

Side corner view. Click image for larger view.