The one property of the diamond, however, which makes it easy of determination is its extraordinary hardness--greater than that of any other mineral. Put in simple language, the hardness of a substance may be described as its power to scratch other substances when drawn across them under pressure. To compare the hardness of two substances we should draw a sharp point of one across a surface of the other under a pressure of the fingers, and note whether a permanent scratch is left. The harder substances will always scratch the softer, and if both have the same hardness they may be made to mutually scratch each other. Since diamond, sapphire, and ruby are the only minerals which are harder than emery they are the only ones which, when drawn across a rough emery surface, will not receive a scratch. Any stone which will not take a scratch from emery is a gem stone and of sufficient interest to be referred to a competent mineralogist. The dissemination of information regarding the lake diamonds through the region of the moraine should serve the twofold purpose of encouraging search for the buried stones and of discovering diamonds in the little collections of "lucky stones" and local curios which accumulate on the clock shelves of country farmhouses. When it is considered that three of the largest diamonds thus far found in the region remained for periods of seven, eight, and sixteen years respectively in the hands of the farming population, it can hardly be doubted that many other diamonds have been found and preserved as local curiosities without their real nature being discovered. If diamonds should be discovered in the moraines of eastern Ohio, of western Pennsylvania, or of western New York, considerable light would thereby be thrown upon the problem of locating the ancestral home. More important than this, however, is the mapping of the Canadian wilderness to the southeastward and eastward of James Bay, in order to determine the direction of ice movement within the region, so that the _tracking_ of the stones already found may be carried nearer their home. The Director of the Geological Survey of Canada is giving attention to this matter, and has also suggested that a study be made of the material found in association with the diamonds in the moraine, so that if possible its source may be discovered. With the discovery of new localities of these emigrant stones and the collection of data regarding the movement of the ice over Canadian territory, it will perhaps be possible the more accurately and definitely to circumscribe their home country, and as its boundaries are drawn closer and closer to pay this popular jewel a visit in its ancestral home, there to learn what we so much desire to know regarding its genesis and its life history. * * * * *