| Description | Line drawing, figure 4 illustrating Kite's paper 'A Register of the Barometer, Thermometer, Hygrometer...& appearance of the Sky, at Gravesend in Kent. For the years 1787 & 1788'.
The accompanying text [pp.22-23] states that: 'Wishing if possible to have an instrument that would of itself indicate the quantity of evaporation, without the trouble of taking it, I had recourse to several expedients: the following I found the least subject to error. (a b c) Fig IV, is a brass wheel with a groove on the circumference, which is very nicely & accurately formed in a turning lathe. The axis of the wheel moves in the upper part of the stand (d) which is of brass. (e a c) is an index connected with the wheel - it has an opening at (a) to allow a small cord to run thro'; & when any degree of motion is given to the wheel, it moves on the scale (k k). (f) is the vessel in which the water is exposed; it is supported by silk, which is secured to the upper part of the wheel at (b). (g) is a weight, which, with the index exactly counterbalances the water...' |