Why the use of tangent arms on older GEMs?

Just wondering why did some of the older GEMs like the Astrophysics 800, and the Meade Research Grade/DS-16 mounts use tangent arms on the DEC axis instead of using a worm gear? Either way, it seems like the machining would not be any harder - just different. The old Star-Liner corporation, and others at the same time and earlier used worm gears for the DEC axis on their GEMs. I suspect that the mount manufactures who incorporated the tangent arm would have also considered a worm gear in there design, so if so is there any advantage at all to using a tangent arm over a worm gear on the DEC axis?

Jim

With a tangent arm you get the leverage of a very large gear without the expense of a very large gear. Before mounts were commonly slewed around the sky by motors, there was no great advantage to using a full gear in declination. Precision gears of that size are certainly more expensive than tangent arms.