Mohs scale of mineral hardness incorporates additional substances that may fall between levels: Comparison between hardness (Mohs) and hardness (Vickers): Mohs scale of mineral hardness The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Created in 1812 by German geologist and mineralogist Friedrich Mohs, it is one of several definitions of hardness in materials science, some of which are more quantitative. The method of comparing hardness by seeing which minerals can visibly scratch others is, however, of great antiquity, having been mentioned by Theophrastus in his treatise
Worshipful Company of Scientific Instrument Makers or using scientific instruments. This could be any kind of scientific instrument: a measuring instrument, like a feeler gauge or an atomic clock, or an imaging instrument like a PET scanner. It might even be a piece of control engineering incorporating many instruments. What makes the Company a community is partly a shared interest in scientific instruments and, more generally, in science and engineering. It is also partly a shared love of good company, of meeting for discussion over food and wine, and of bringing partners or guests to a grand banquet in distinguished surroundings. But what makes the Company