(WITH THREE FIGURES) SOME years ago, when the author had to make use of the klinostat for extensive experimentation, the work went so slowly with one machine that means were sought to secure the operation of several klinostats at the same time without incurring the expense incident to the purchase of a number of the costly machines in common use. After some attempts to construct apparatus on too light and too cheap a scale, the apparatus here described was designed and manufactured with the cooperation of Mr. RALPH MILLER, at that time university mechanician. It has been used extensively for seven years, and has answered every demand made upon it. It is herewith described partly in response to several inquiries by men in other universities, and partly with the hope that it will be welcomed as offering a means for various kinds of research now practically impossible with the spring machines. This apparatus can be provided with a horizontal and a vertical klinostat to run at the same time, the whole costing less than a Pfeffer machine; and the number of turn-tables can be increased almost indefinitely. Moreover, it will carry a much greater load than the spring klinostats. I. CENTRIFUGES.