A MAHOGANY CASED HOOKE'S OTHEOMETERPHILLIP COLLINS, MERTON, DEVON, LATE 20th CENTURYThe printed paper scale with herringbone border enclosing amplified reversed scale calibrated in barometric inches and with the ual early-type weather observations for both SUMMER and WINTER beneathments Fair if Fall and Foul if Rise and title HOOKE'S OTHEOMETER within a scroll decorated to surround to upper margin, applied with syphon tube incorporating large silvered sealed bulb part-filled with red-stained oil opposing column open to the atmosphere at the top for reading against the scale to the centre, the lower left hand corner of the scale with explanation passage over oval cartouche inscribed P. Collins, MERTON, the rectangular glazed case cavetto cornice, simple brass slide recording pointer to right hand side and conforming base, the rear with applied paper build label.68.5cm (27ins) high, 21.5cm (8.5ins) wide, 7c, (2.75ins) deep.Provenance: The exhibition collection of Barometer World Meum, Merton, Devon.Within the explanation passage printed to the lower left-hand corner of the paper scale Phillip Collins notes that Robert Hooke's diary for 12th July 1677 records It is now very evident that the Otheometer moves directly opposite to the Barometer. The present instrument is an improved version of the Otheometer as devised/described by Hooke and indicates barometric pressure via the column of fluid in the tube which rises and falls duepressive effect atmospheric pressure has on the air-filled bulb. The large diameter of the bulb in relation to the bore of the tube amplifies the motion of the fluid hence the enlarged scale which is also in reverse as increase in pressure caes the air volume of the air in the bulb to reduce. Hooke derived the name form the Greek othe which means to ph, as this is action that atmospheric pressure has on the fluid within the column. A notable fault with Hooke's design is the effect that temperature has on the volume of air in bulb. For this improved model the surface of the chamber has been blown with a second wall enclosing an evacuated jacket around the first, which in-turn has been silvered to reduce the effect sunlight would have on the chamber's internal air temperature; this refinement requires a great deal of skill from the glass blower.