The particular specimen of Weston instrument shown is called a "milammeter", because a current may be directly measured with it in "milli-amperes", or thousandths of an ampere.Condensation of unit and prefix happens sometimes when the prefix and unit meet in a vowel. Megavolts and Gigavolts are uncondensed, but Megohms and Gigohms are condensed. Milamps would seem to follow the same rule as Megohms. Not clear why it didn't last. Is a front vowel more sticky than a back vowel? Incidentally, Weston was among the companies that followed Social Economics, treating workers well and receiving quality and loyalty in return. Newark, America was a rich city with abundant hi-tech jobs as late as the 1960s.
The current icon shows Polistra using a Personal Equation Machine.