The book "Controlled Pulmonary Drug Delivery" describes the inhaler this way:
In 1864 another step forward with dry powder inhalation took place. Alfred E. Newman applied for a patent in London after correspondence with Dr. James in New York. The dry powder device resembled a mantle clock with an orifice at one side, inside was a mesh and a crank shaft with feathers to beat the powder creating a dust, which would pass through the mesh towards the mouth. It was not especially portable, but Newton recognized that the powder needed to be pulverized into a fine dust and that it should be kept dry, two essentials of modern dry powder inhalers. The device was designed for the delivery of potassium chlorate which today is recognized as a lung irritant. (1, page 60)The authors also note that while dry powder inhalation was "in vogue" during the 1860s, it was generally meant to treat diseases of the throat such as laryngitis. Still, it was a revolutionary concept and a precursor -- albeit large, bulky, un-portable, and probably -- to modern dry powder inhalers.
The device may also have been used for tuberculosis. (2).
Quality pictures of the device can be observed by checking out either of the links in the references below.