2157. The mode of ventilating at Frogmore has been kindly supplied to us by the engineer, Mr. Jones. Fig. 646. is a perspective view of the house, in which a is an iron shaft running the whole length of the house, and working in brass chains or bearings. Fixed on this shaft, and opposite the centre of each front light, is a brass pinion, working into a toothed quadrant attached to the bottom rail of each light. The shaft being turned round by means of the handle (b), the quadrants are, of course, either thrown out, or drawn in, as the handle is moved backward or forward; and the whole of the lights, each moving on its centre at top, are simultaneously opened or closed to the extent required; the smallest or widest opening being given with equal ease at the pleasure of the gardener. Fig. 647. is a section of the same house, in which the handle and quadrant of the apparatus for opening and closing the front lights are shown at a b. In the back wall under each intermediate top light is a ventilating frame, shown in the section at c; and above these frames, outside the house, are a corresponding number of open-work gratings, marked d in figs. 646. and 647. Flues or chambers in the wall are shown at e in fig. 647; and these flues are the length of the ventilating frames; the doors of which open into the flues at bottom, while the gratings cover their openings at top. When it is desired thoroughly to ventilate the house, and the front lights are opened, it is only necessary to turn the screw or worm (f), which is connected by the rod (g) to the lever (h); the lever being fixed on the end of a wrought-iron shaft, running the whole length of the house, and secured to the back wall; and on this shaft are fixed small levers, as at i, one of which is attached by a wrought-iron link to each ventilating door. In raising or lowering the lever (h), by means of the worm (f), the shaft is turned partially round, the levers shown at i are drawn backwards or forwards, and the doors are opened or closed the whole length of the house by one simple operation; the tightening of the screw at o securing the whole at any extent of opening that may be required. (J. B. Jones.)
