The improvements in Chimney Ventilators illustrated by the above engravings were patented by Mortiner M. Camp, of New Haven, Conn., August 17,1852. Figure 1 is a perspective view of the whole ventilator, and figure 2 is a vertical section through the centre, with the whole of the two wheels, c cand c , shown in perspective. The same letters represent the same parts in both engravings. A, figure 1, is a cylinder with openings cut for the admission of currents of air, and a dirrect the current in an opposite direction. The wings of these fan wheels are broader at their bases or where they are attached to the shaft, so as nearly to fill the cylinders in which they revolve, but taper toward their opposite ends, where they are curved and pointed so as to fit around the points of the hollow cones over which they turn in the manner represented in figure 2. Whenever a current of air strikes the upper ian wheel, which will always be at an inclination to its shatt, being directed in its entrance through the cylinder, a rapid motion is given to both wheels, and the air from the upper cylinder is carried downward by the spiral wings, and passes sut again between the hollow cone, E, spreading or conical base, D, which covers the lower portion of the ventilator. Guide plates or buckets, B, direct the current of air coming from any direction through the rectangular openings, C, upon the spiral vertical fan wheel, c c, hung upon the shaft, a a, in bearings, b b ; F is an inverted hollow cone with a cylindrical base, which forms the base of the ventilator, and within which is the spiral fan wheel, t e, upon the same shaft with c c, and similar to it in construction, except that the latter is inverted upon the shaft in order to and the base, D, of the cylinder, A. The same motion being communicated to the lower wheel draws the smoke upward and tends to expel it from the top, between the hollow conical portion, E, and the smaller inverted cone, around which the wheel, e e, revolves, as shown in figure 1. This arrangement will doubtless preclude the air from passing down the pipe, F, while the wheel, e , is in motion, which will always be the case when there are currents of air sufficient to drive it. More information may be obtained by letter addressed to Cannon & Brother, 134 Chapel street, New Haven, Conn., who are tole agents for selling rights, and who will attend promptly to any communication.