The answer is: that you must find out in the same way as you found out about your motor car before buying it. You didn’t buy your car because a salesman said it was a good car and because he made you sign a slip and because he promised you, as he departed, a quick delivery. No, indeed, you tried out the car first or last and you asked your friends, who had purchased the same make, how they liked it and you talked a lot about cost of upkeep, efficiency, wear and economy and the service possible to be had from the makers. Didn’t you? Well, the same process is necessary in buying a vacuum cleaner or any other piece of machinery for the house and every Domiologist knows this to be a fact. “ALL IS NOT GOLD, ETC.” All vacuum cleaners look charming and shiny and all seem very perfect in the shop! And they all do their stunts beautifully as the skilled operator thrillingly draws designs in the flour or bi-carbonate (clean, unclinging dirt) on the patient carpet. The operator talks glibly, often failing to give the failings of his machine because he doesn’t know them. So the only thing to do is to try it, in your own home, under your own special conditions, and see that it gets under your furniture, removes threads, lint, hair, dust, matches and other substances with the least possible noise (for noise wears on the operator’s nerves and raises a dislike for the cleaner) and the least possible effort. It must be light weight, easy to operate and economical and durable. There is nothing so hard to remove as “natural born dust.” It becomes imbedded in the carpet and it takes force to remove it and the sort of force that will not destroy. Taking up the differences in the various machines, it is the better part of valor to know what the nature of our prey is before we start to hunt! So we will examine the animal dust in its hunting-grounds. DUST’S HUNTING GROUNDS In your home you have on the floor woolen or grass fabrics; rugs large and small, and carpets, grass rugs and mattings. The carpets or rugs may have a long nap loosely woven (Chinese) Axminster, Wilton, Velvet Chenille or the pile in loops (Brussels) or just woven threads such as ingrain without any nap or pile. Grass rugs (Crex, etc.) and matting are of this kind. It is easily understood that, as the carpet or flooring is walked on, the dust becomes deeply imbedded and gets tangled up in the fibres, and that surface sweeping never can take out the dust and you have to send carpets each year to the cleaners to restore their color, etc. Above the floors are, of course, the hangings, mattresses, books, pictures, moldings, ceilings and walls. As to the dust and the litter, such as matches, hair, lint, collects, 85%-90% of it gathers on the floor, and 10%-15% in the rest of the room. Therefore the cleaning is reduced on the upper regions if the floor is kept really clean.